The L-1011 Project

L-1011 Engine: Rotating Assemblies

2012-01-27T08:39:00.001-05:00

The RB.211 engines used on the Lockheed L-1011 have three rotating assemblies rather than two. Many more stages would be necessary to get the same compressions ratio which would create a very long engine. The 3 spooled design results in a short rigid engine which has less parts.

Compressors are referenced as a Low Pressure (LP), Intermediate Pressure (IP) and High Pressure (HP).

The HP compressor drives accessories through a step aside gear box. Accessories are mounted on the LH and LP compressor case.

L-1011 Engine: RB211-524B-02 Engine (71-1)

2012-01-23T07:49:00.001-05:00

The Rolls Royce RB211-524 engine is flat rated to 84ºF ambient temperature with 50,000 lbs. of thrust. The engine has three spools: N1, N2 and N3.

N1 - Low Pressure (LP) compressor which a single stance fan and three stage turbine.
N2 - Intermediate Pressure (IP) compressor with a 7 stage axial flow single stage turbine
N3 - High Pressure (HP) compressors with a 6 stage axial flow single stage turbine

Direction of orations is counterclockwise as viewed from the rear. The image above show the hot stream air slow as well as the cold stream airflow.

L-1011 APU: APU Application (49-11)

2012-01-19T08:39:00.002-05:00

Flow of pneumatic air from the APU load compressor can be monitored and controlled at the Flight Engineer's Engine Bleed Control Panel. Duct pressure may be monitored on the duct pressure indicators.

As can be seen from the panel schematic, APU pneumatic air is available for engine starting, ATM operation, or air conditioning pack operation. APU air is never mixed with air from another source to prevent damage to the APU.

L-1011 APU: APU Fuel Supply (49-10)

2012-01-18T07:43:00.001-05:00

Fuel for the APU is supplied by the aircraft fuel system through the No. 2 engine fuel tank valve and fuel line. By using cross feed, fuel can be supplied by any tank to the APU. Two emergency shutoff valves are provided to isolate fuel from the APU in case of fire. In-transit lights for the valves are located on the Flight Engineer's fuel panel.

L-1011 APU: Fault Flags (49-7)

2012-01-17T07:57:00.001-05:00

There are four fault circuits that will cause the APU to shut down to protect against malfunctions that could damage the APU. The fault circuits are:

OVERSPEED N2 - Free turbine speed in excess of 110%
LOW PRESS OIL - Oil pressure drop below 50 PSI for 10 seconds with ≥ 55% RPM
HIGH OIL TEMP - Protects against high oil temperature
OVERTEMP TGT - Protects against over temperature TGT during starting and in normal operation.

Any fault or combination of faults will shut down the APU automatically.

L-1011 APU: APU Controls (49-6)

2012-01-13T07:41:00.000-05:00

Most of the controls and indicators for normal operation are located on the APU control panel at the Flight Engineer's station.

Two indicators are provided for monitoring gas generator RPM and TGT.

There are seven advisory lights to indicate abnormal conditions. Switches for controlling starting, stopping, and pneumatic air supply controls are located on the control panel. A switch for arming the Auto Fire Shutdown circuit to allow unattended operation of the APU is also located on the APU control panel.

L-1011 APU: APU Doors (49-5)

2012-01-12T07:55:00.000-05:00

Ambient air enters the gas generator through the engine inlet door. The air passes through a four stage compressor, three axial and one centrifugal stage, and enters a combustion chamber. Fuel is mixed with compressed air and ignited. The resultant gasses expand driving the gas generator turbine and the free turbine.

The free turbine is driven at a constant speed to maintain a frequency of 400Hz at the APU generator. The APU generator is driven by the free free turbine through an adapter gearbox. A cooling fan is also driven by the adapter gearbox.

The cooling fan provides cooling airflow for the APU hot section, exhaust manifold and oil cooling.

A load compressor is also driven by the free turbine. The load compressor receives ambient air through an opening in the fuselage. The air passes through a set of inlet guide vanes which control the amount of air to the load compressor. Air from the load compressor is then routed to the aircraft systems if needed, excess load compressor output is dumped into the exhaust manifold through a surge dump valve.

L-1011 APU: APU Operation and Location (49-3/4)

2012-01-11T07:36:00.001-05:00

The APU can be started from sea level to flight level 250 and will operate up to flight level 310.

The APU is installed at the rear of the aircraft below the No. 2 engine "S" duct forward of the No. 2 engine firewall. The APU is contained in a fireproof compartment and the platform the APU is mounted on is part of the aircraft skin.

L-1011 APU: Overview (49-1/2)

2012-01-10T07:15:00.001-05:00

The Auxiliary Power Unit (APU) is installed on the L-1011 as an auxiliary power source to be used primarily on the ground. The APU can also be used in flight as a back-up for the aircraft's pneumatic, hydraulic, and electrical systems.

The APU will supply pneumatic power for air conditioning, engine starting and to power the ATM's for hydraulic power.

The APU generator can supply up to 81 KW to an altitude of 14,000 and 54 KW above 14,000 feet.

L-1011 Navigation: INS CDU (34-43)

2012-01-05T07:27:00.000-05:00

This is the CDU as it appears with the test switch pressed. The intensity of all controls which are shown illuminated is controlled by the DIM knob on top of the data selector. The illumination of the keyboard is controlled through the center pedestal rheostat (external to the device).

L-1011 Navigation: Model Selector Unit (INS) (34-43)

2012-01-04T07:33:00.000-05:00

The attitude position (ATT) disables the navigation computer but retains the platform for attitude reference.

There are two mechanical stops - one between the standby and align positions of the switch, and one between the NAV and ATT positions. To move the switch past the stop, the switch must be pulled up and rotated past the stop. Once the mode selector has been placed in the NAV position, it can be returned to the align position without dumping the program in the computer. However, if the switch is placed in either the standby or attitude positions, the program is cleared and the set must be realigned before it can be used for navigation.

L-1011 Navigation: Inertial Navigation Systems (34-43)

2012-01-03T07:50:00.000-05:00

The NAV position is the normal operating position. The mode switch must be placed to NAv, and the computer must enter the NAV mode prior to moving the aircraft. If the aircraft is moved prior to entering the NAV mode, the computer will dump its program and the set will have to re-aligned. If the mode selector is place directly to NAV and present position inserted, the set will cycle through the standby and align modes and enter the NAV mode; however, placing the switch to NAV directly would be an abnormal procedure.

Automatic overheat protection is disabled in the NAV mode to prevent inadvertent shutdown in flight.

L-1011 Navigation: Inertial Navigation System (34-38)

2012-01-01T17:31:00.000-05:00

Additional controls for the Inertial Navigation System are the mode selectors, the control display units and the associated aircraft interfaces.

The standby position erects the gyros and brings he computer up to temperature. When the selector switch is standby, automatic overheat shutdown protection is also provided.

The mode selector switch is normally positioned directly from off to align. The computer will automatically progress through the standby mode and enter the alignment mode. The alignment cycle requires a minimum of 11.5 minutes and must be completed before the aircraft is taxied. Automatic overheat shutdown protection is also provides in the ALIGN mode.

The green light indicates that alignment process has progressed to he point where the set is capable of navigation. This light will illuminate with the mode selector switch in the align position and extinguishes when the computer entered the navigation mode.

L-1011 Navigation: Inertial Navigation System (34-43-6/7)

2011-12-30T09:39:00.001-05:00

The INUs are located in the forward electronic service center against the forward bulkhead. The batteries are located in the left-hand equipment rack. These areas are all accessible while in flight.

The MSUs are located on the Pilot's Overhead Pane, and the CDUs are located on the center console. CDU No. 1 is forward of the throttles on the Captain's side; CDU No. 2 is on the First Officer's side forward of the throttles; and CDU No. 3 is center aft of the throttles.

L-1011 Navigation: Inertial Navigation System (34-43-5)

2011-12-29T08:36:00.001-05:00

The INS system hardware consists of for components:

The Inertial Navigation Unit (INU), which contains the platform and computer.
The Control Display Unit (CDU), which is essentially a remote terminal by which the crew communicates with the computer.
The mode selector (MSU), is a function switch for the computer.
The final item is a battery capable of powering the system for up to 15 minutes in case of loss of ship's power.

L-1011 Navigation: Inertial Navigation System (34-43-4)

2011-12-28T08:42:00.001-05:00

Once alignment is complete and the aircraft starts moving, the computer converts acceleration signals to a series of vectors. By algebraically summing the vector, the computer measures distance traveled in north-south and east-west directions. The computer upgrades position extremely rapidly (in terms of microseconds) and is therefore capable of detaching very small variations in velocity.
In the short term, INS computers are very accurate. OVer the long term, however, the computer accumulates computations errors. The magnitude of these errors becomes progressively greater with time. When two or more INSs are operations, the crew can observe the present positions slowly drift apart. Since the computers do drift, there is a built-in compensation circuit. When the INS is shutdown, the position is recorded. When the set is next aligned, the difference between shutdown position and alignment position is measured and an appropriate correction favor is then applied to further computations.

L-1011 Navigation: Inertial Navigation System (INS) (34-43-3)

2011-12-26T20:33:00.001-05:00

Before the INS can begin operation, the platform must be aligned to true north. When power is applied and the gyros come up to speed, the playroom is erected just as a conventional attitude gyre is erected. Once the platform is erect, the accelerometers sense the earth's rotation. The computer determines the direction of motion caused by the earth's rotation relative to the platform axis. In doing so, the computer determines the orientation oft he platform to true north. It is useful to remember that all computer computations are in reference to true north.

After orientation to true north, the computer measures the rate of earth rotation. By comparing the measured earth rate to earth rate data stored in the computer's memory, the computer can determine its latitude. However, the INS cannot determine its longitude. Before navigation can commence, the crew must insert the coordinates at which the platform is erected into the computer's memory.

L-1011 Navigation: Inertial Navigation System (34-43)

2011-12-24T16:42:00.000-05:00

The next few postings will cover an interesting system of the L-1011 which is the Delco Carousel Inertial Navigation System. This system was not only used on the L-1011, however, most long range 1011s ended up equipped with the Delco Carousel system. The Delos Carousel system also has a really neat old computer interface.

In general, however, Inertial Navigation Systems (INS) are a spin off of the ballistic missile. They are highly compact, accurate, reliable and virtually automatic. The heart of the system is a cluster of accelerometers mounted on a gyro-stabilized platform. Acceleration signals are fed to a specialized computer that converts the signals to vectors in both north-south and east-west directions.

L-1011 Navigation: Radar Control Panel (34-19.20.21)

2011-12-23T21:19:00.000-05:00

The switches across the top of the radar control panel have the following functions:

OFF - both radar systems are off.
STBY - the selected RT entered a three minute warmup period.
NORM - narrow beam scan for selected radar. The other radar is off. If NORM is selected immediately, the card will still go through its three minute warmup operation.
CONT - [Contrast] blanks out returns of maximum intensity weather.
MAP - provides expanded beam for ground mapping.
TEST - projects a test pattern on scopes and illuminates all the control lights. The selected system also starts the warmup period.

The antenna is capable of stabilizing with the aircraft attitude of 25º roll and 15º pitch. Manual pitch tilting is permitted with the UP/DN pitch control knob on the right hand side of the panel.

The variable gain control switch on the left hand side of the panel allows amplification (gain up) of the radar return signal on the scopes. When in the AUTO position, the gain is automatically controlled.

L-1011 Navigation: Radar Control Head (34-17)

2011-12-22T07:54:00.003-05:00

The radar control head is located on the aft center console. The radar scoops are mounted on the opposite ends of the Capt. and F/O's instrument panels.

A selector is provided to select either the No.1 or No.2 radar system. With the No.1 selected the No.1 REC/TRANS and No.1 VG/INS are being used to align the antenna and produce the radar scope images. With the No.2 selected, the No.2 REC/TRANS and No.2 VG/INS are being used. Again, both scope would now show radar images from the No.2 system. On the L-1011 it is not possible to operate the two radar scopes on opposite systems.

The VG/INS provides stabilization to the radar antenna.

L-1011 Navigation: Transponder (34-15)

2011-12-20T10:13:00.002-05:00

In the Lockheed L-1011 cockpit the transponder is located on the center console. A three-position transponder select switch is provider in most cases:

#1, #1 transponder is being used, #2 Standby
Standby, both transponders are warmed up (as long as power on aircraft) but neither is operating.
#2, #3 transponder is being used, #1 in Standby

The mode select switch determines whether A domestic or B international coding is being used. (More modern devices include other modes as well as TCAS).

A three-position altitude reporting switch is provided:

#1, ADC #1 is being used for altitude reporting
OFF ... the system is off
#2, ADC #2 is being used for altitude reporting

The fault light indicates a fault within the selected system (amber). This should prompt the pilots to select the other transponder. The IDENT button provides an additional pulse reply. IDENT pulse lasts for 20 seconds after IDENT button is release.

Pushing the test button also illuminates the REPLY light.

L-1011 Navigation: 12 Hour Clock (34-14)

2011-12-19T20:38:00.003-05:00

There are two 12-hour electric clocks, one on the Captains instrument panel and one on the first officers' instrument panel. On some Lockheed L-1011's a digital type clock was installed in place of the 12 hour clocks. In most cases the clock installed on the flight engineer station was either a digital style clock or a 24h clock. The clock is set normally with the SET or GMT knob. The SWP knob on the 12h clock has the following functions:

Press first time up to 12 minutes of sweep
Press second time to reset the sweep time

L-1011 Navigation: Marker Beacon Lights (34-13)

2011-12-16T09:22:00.001-05:00

Marker Beacon Lights are tested by pushing each light individually. The light s are labeled and color coded for the Outer, Middle and Airways marker.

Holding the TEST switch on the associated radio head will sequentially test the marker beacon lights. AIRWAYS comes on then goes out, then MIDDLE comes on then goes out and lastly OUTER comes on then goes out. As each light ones on, it's associated identification tone is also heard.

L-1011 Navigation: ADF (34-12)

2011-12-15T14:02:00.000-05:00

The dual ADF panel is located on the center console. Besides the triple frequency selector there are switches for BFO (Beat Frequency Oscillator) and a selector switch for ANT - OFF - ADF.

L-1011 Navigation: RDDMI (34-7)

2011-12-12T07:56:00.001-05:00

A DME failure will cause a fail flag to appear in the DME window (arrow 1). A VHF failure will cause the appropriate VOR1 or VOR2 fail flag to appear (arrow 2).

L-1011 Navigation: RDDMI (34-6)

2011-12-11T17:09:00.001-05:00

The RDDMI's are located on the Captain and F/O's instrument panels. They display the following NAV data:

NAV 1 DME
NAV 2 DME
And a combination of VOR and ADF directional information, depending on pilot selection.

The VOR and ADF source selection is made with the black switches on the bottom left and bottom right of the instrument. A flag right above the switch shows which NAV source is being displayed by which needle.

L-1011 Navigation: HSI Fail Flags (34-4)

2011-12-03T14:58:00.001-05:00

A VOR or localizer failure or power failure will cause the NAV fail flags to come into view, depending on frequency selection.

A glideslope or V/NAV failure will cause the glideslope flag to appear.

L-1011 Navigation: HSI Location (34-3)

2011-12-02T12:52:00.001-05:00

The primary navigation display in the L-1011 cockpit is the Horizontal Situation Indicator (HSI). Here are the basic function elements of the HSI:

The deviation bar works the same as on other HSI's or CDI's
The type of radios at a is displayed in the small windows (NAV data source indicators) which are VOR 1, VOR 2, ILS 1 and ILS 2
The cursor arrow is controlled by the two course knobs on the autopilot NAV MODE panel.
Triangular VOR indications are provided when the HSI is in VOR mode.
Glideslope display is provided when turned to an ILS. While using VOR, the glideslope display is shuttered.
The ALERT 1 Minute from R-NAV Waypoint is also used in conjunction with the INS and NAV equipment.

L-1011 Navigation: VHF NAF (34-1/2)

2011-12-01T09:39:00.001-05:00

The Lockheed L-1011 as two in depended VHF NAV systems. The control heads are not located as part of the center console, but are part of the glare shield (see image above). A four-position DME control switch is also provided (outlined). The DME control switch has the following functions:

STBY - permits audio reception but no search display
NORM - permits reception of up to 200 NM
OVRD - permits reception of up to 400 NM
TEST - provides the following interactions on the RDDMI within a 9 second period after pushing the spring loaded switch to TEST: a) DME fail flag, b) Four dashes followed by c) Four zeros

L-1011 Landing Gear and Brakes: Nose Wheel Steering (32-27/28)

2011-11-30T11:21:00.001-05:00

The nose wheel steering control wheel is located on the Captain's and First Officer's side console.

Rudder pedal steering is only available when the nose landing gear strut is compressed. If rudder input is being used at that time, the nose wheel will automatically go to the rudder position. The amount of nose wheel steering applied will be proportional tot he amount of rudder applied. The rudder pedal can be used up to plus or minus 12º of steering.

Control wheel steering is active anytime down hydraulic pressure is available to the nose landing gear. It has priority over rudder pedal steering and will override at any time. Control wheel steering will turn the nose gear plus or minus 64º.

L-1011 Landing Gear and Brakes: Brake Temperature Panel (32-25)

2011-11-29T12:44:00.001-05:00

The brake temperature panel is located in the upper right hand corner of the Flight Engineer's panel. There is also a brake temperature light on the pilots' caution and warning panel on the center instrument panel. This panel can monitor all eight brakes and show the respective brake temperature on a vertical temperature gauge.

L-1011 Landing Gear and Brake: Automatic Braking Control Panel (32-23)

2011-11-28T12:34:00.001-05:00

The Automatic Braking System (ABS) automatically applies the aircraft brakes promptly and smoothly on landing or a rejected takeoff. Using this system lessens tire and brake wear, enhances passenger comfort and reduces Pilot workload.

The autobraking panel is located on the Pilot's overhead panel and contains a momentary on switch light with the split legends ARMED and FAIL and a six position rotary mode selector. The six positions are INOP, OFF, MIN, MED, MAX and TAKEOFF. There are four preselected deceleration rates that can be used with he ABS system. They are:

MODE PSI/SEC RAMP RATE DECEL RATE
MIN 650 4.0 FT/SEC/SEC
MED 650 6.0 FT/SEC/SEC
MAX 1,300 MAX (3000 PSI)
TAKEOFF 15,000 MAX (3000 PSI)

Brake pressure is automatically controlled to compensate for use of spoilers, reverse thrust and other decelerating forces to maintain a constant deceleration.

L-1011 Flight Controls and Brakes: Anti-Skid System (32-22)

2011-11-27T07:30:00.001-05:00

The anti-skid panel is located in the Pilot's overhead panel. Anti-skid is available with both the normal and alternate brake system. Which brake system the anti-skid is working with is determined by the position of the brake select switch. Located on the Pilot's caution and warning panel is an anti-skid light which will illuminate under following conditions:

If the Gear is down and the anti-skid is off
If the anti-skid is on and the parking brakes are set

L-1011 Landing Gear and Brake: Parking Brake Handle (32-21)

2011-11-23T09:29:00.001-05:00

The parking brake pull knob is located on the center console just below the gear horn cutout switch. To set the parking brakes, apply brake pressure with the toe brakes, pull the parking brake knob and release the toe brakes. A red light next to the parking brake knob for the Captain, and a red light only at the First Officer's position will illuminate indicating the parking brakes are set and pressure is present at the brakes.

L-1011 Landing Gear and Brakes: Brakes System Indicators (32-20)

2011-11-22T07:22:00.001-05:00

Located below the gear switch and position lights is the brake pressure gauge which reads "B" or "C" system accumulator pressure. Below the brake pressure gauge is the brake select switch. This switch selects which hydraulic system will be used for braking. "B" system is used for alternate. "B" and "C" system brake accumulator low pressure lights are located on the Flight Engineer's annunciator panel. The Pilot's caution and warning panel will display a LOW BRAKE PRESSURE light should either accumulator light be illuminated.

L-1011 Landing Gear and Brakes: Mechanical Brakes (32-19)

2011-11-19T17:16:00.001-05:00

The Lockheed L-1011 uses hydraulically actuated multiple disk type brakes. The brakes are self-adjusting and incorporate direct mechanical wear indicators at the disk.

The brake system uses a dual cable run from the brake pedals back to the dual brake valve located in the hydraulic service center. The Captain's cable run controls system "B" dual brake valve and the First Officer's control system "C". Both dual brake valves are mechanically linked together. Either operator exercises both brake valves simultaneously. A bunge system is incorporated outboard of each brake valve to protect against possible jams.

L-1011 Landing Gear and Brakes: NLG Visual Downlock (32-14)

2011-11-18T07:37:00.001-05:00

Located on the jury brace assembly of then nose gear attached two red rods which align themselves when the jury brace goes over center. On the aft wall of the forward electronic service center is located a viewer. Access to the forward electronic service center for visual inspection of the alignment rods is possible from the flight station.

L-1011 Landing Gear and Brakes: MLG Visual Downlock

2011-11-16T16:20:00.001-05:00

The L-1011 has a rather interesting way of indicating main landing gear down lock. Located on the top of each wing directly over the main gear is a circular pop-up indicator. When the main gear is down and locked, a mechanical linkage pops up this indicator about 1/2" oboe the wing surface. The linkage is driven by the jury brace actuator rod end.

L-1011 Landing Gear and Brakes: MLG and NLG Up-lock (32-11/12)

2011-11-13T07:29:00.001-05:00

With the landing ear in the retracted position, the main landing gear is healed by resting on the triangular door beam, not the actual door. The gear door lock and the gear up-lock are one and the same. With the gear switch placed in the neutral position, all hydraulic power is removed from the gear and it rides between two shock absorbing snubbers.

The nose landing gear is held in the retracted position mechanically by the up-lock device on the aft wall of the nose gear wheel well. The two pairs of doors are mechanically sequenced closed by the retracting action of the gear.

L-1011 Landing Gear and Brakes: Gear or Door Lights (32-10)

2011-11-12T20:50:00.001-05:00

There are three GEAR or DOOR lights located on the second officers panel which are used to determine which gear or door is causing a problem.

With the gear down and locked as indicated by the three green lights and the DOOR and IN TRANS lights on, the GAR or DOOR lights on the Send Officer's panel indicates the problem is with the left and right main dear doors.

L-1011 Landing Gear and Brakes: Gear Switch and Position Lights (32-6)

2011-11-11T15:53:00.001-05:00

The Gear Switch and position lights are located on the Pilot's center instrument panel. The three green lights on top are the congenital down and locked indication. The red IN TRANS light is a total disagreement light concerning everything in the gear system. The red DOOR light is a disagreement light dealing only with the doors. The amber TRUCK light illuminates anytime the truck is not level +/- 2 1/2º degrees of tilt. All of these position lights receive their information from the proximity system. The gear switch is a three-position switch which incorporates a down lock release button.

L-1011 Landing Gear and Brakes: Overview (32-1/2/3)

2011-11-10T07:39:00.003-05:00

The Lockheed L-1011 aircraft landing gear uses a tricycle type configuration and is of conventional design and construction. It is electrically controlled and hydraulically operated using "C" system hydraulic pressure.

Because of the four wheel bogie, dual tandem arrangement, the pavement stress is less than most other jet transport type aircraft. As you can see, the gear is quite large (see below) when compared to an average height person. The inboard Main Landing Gear Doors also use "C" system hydraulic pressure.

L-1011 Flight Instruments: Instrument Difference Warnings (Comparator) (31-33/37)

2011-11-09T07:49:00.001-05:00

The instrument comparator monitors for instrument differences. If an instrument difference occurs, the appropriate warning flag will appear in the Captain and F/O's instrument comparator panel.

A difference of 6 knots to 10 knots between the IAS indicators will cause the AIRSPEED instrument comparator flag to appear. An IAS fail flag might also appear in the IAS indicator, but not necessarily. The higher the indicated speed, the grater the error must be to get a comparison flag. At 200 knots, a 6 knot difference will trip the comparator. A 10 knot difference required at 450 knots.

After an initial VG/ISS failure, a difference in attitude indications exceeding 5º will cause an ATTITUDE comparison flag to appear on both instrument comparator panels. an ATT flag may appear on the ADI, but not necessarily.

A difference of altitude indications of between 100 and 240 feet will cause the ALTITUDE comparison flags to appear.

The difference required to get a warning increases with altitude. Approximately 100 feet at sea level will increase to 240 feet at 40,000 feet.

The Instrument Comparator threshold is doubled if the vertical speed exceeds 800 FPM.

A difference of heading indications of between 6º and 15º will cause the HEADING comparison flags to appear. The difference required for the HEADING flag increases as the angle of bank increases. A HDG flag in the HSI could also be present, but not necessarily.

L-1011 Flight Instruments: Heading Failures (31-32)

2011-11-08T08:21:00.000-05:00

Any heading system failure will cause the heading Flag to appear on both the RDDMI as well as the HSI. Here is how a heading failure would manifest itself:

The associated RDDMI compass card would have a heading flag and the card would freeze in place with the data from the last good heading. However, the VOR/ADF needles will show the relative bearing.

Heading flags will also be in view while slewing the compasses with the COMPASS panel controls.

The HSI compass cards also provide inputs to the instrument comparator system and any difference between the two cards will trigger the comparator error to be shown. If a difference of between 6º in level flight, and 15º in a 30º bank occurs between the two HSI's, a HEADING warning flag will appear on both comparator panels.

L-1011 Dimensions (Part 4)

2011-11-07T11:21:00.004-05:00

In this posting I am showing you the basic differences between the -1 and the -500 model aircraft. The second image is an interesting detail drawing of the gear door. The images are taken from an engineering publication released by Lockheed-California in the 1980s.

L-1011 Flight Instruments: Compass Control Panel (31-29)

2011-11-07T09:23:00.004-05:00

When DG is elected on the COMPASS panel the following happens:

DG is free of MAG inputs
The directional gyro may be slewed to any position at two different speeds.
In this case, the SYNC operator does not work because the are not magnetic indicators to synchronize

When MAG is re-selected, the DG will align to magnetic north as received from the MAG Flux at a rapid rate.

When operating in the DG mode, there is no indication of DG mode operation except for the DG light on the compass control panel.

L-1011 Dimensions (Part 3)

2011-11-06T08:36:00.002-05:00

The first two images show the L-1011-1 split into Fuselage Sections. Typically Fuselage Sections are measured in inches from the datum line. Click on the image to enlarge to see the full details.

The last image of this positing shows the door and landing gear dimensions for the L-1011-1.

L-1011 Flight Instruments: Standby Horizon (31-25)

2011-11-06T08:13:00.001-05:00

The standby horizon is a completely self-contained unit and is located on the Pilot's center instrument panel. It is powered from the AC standby bus. The cage know may be used to erect the horizon. Flags on the instrument show when the gyro is caged or when power to the device is lost (depending on make or model of the standby horizon). Most standby horizons deployed on the L-1011 had been made by SFENA.

L-1011 Flight Instruments: Heading Reference System (31-27/28)

2011-11-05T10:15:00.000-04:00

The primary displays for the heading reference system are the Captain and F/O's HSI and RDDMI compass cards.

Two compass control panels are located on the pilot's overhead. A selector switch for MAG or DG is provided. When MAG is selected the MAG light on the switch is on in this case:

Gyro reference switches to Magnetic north.
May be slewed but will realign to MAG north.
Sync indicator shows difference between indicated heading and MAG heading

The DG's automatically align to MAG north at a rapid rate when electrical power is applied.

L-1011 Flight Instruments: ADI Failures (31-21)

2011-11-04T07:38:00.000-04:00

The Captain's ADI on the L1011 has inputs from INS 1 and Vertical Gyro #3. The F/O's ADI has inputs from INS 2 and VG #3. The inputs are compared in the ADI instrument itself and outputs are then sent to the instrument comparator monitor which signals the appropriate attitude flag or the ATT 3 annunciator light on the center panel annunciator cluster.

Once a failure has been sensed, the remaining VG/INS's are monitored for validity only. Because there are only two remaining VG/INS's the comparator system can only warn of a difference between them. This is done by presenting an an attitude flag on both instrument comparators.

L-1011 Flight Instruments: Attitude Indicator Failures (31-19)

2011-11-03T10:43:00.004-04:00

The Attitude Flag appears with first INS failure or instrument failure.
The Speed Flag appears if there is a power failure. The speed command pointer will bias out of view with an invalid signal.
The expanded localizer deviation indicator is covered. The shutter appears if a localizer frequency is tuned and there is an invalid input or there is a power supply failure. Also when a VOR frequency is tuned.
Flight Director flags come into view with signal loss from APFDS computers, power failure or incompatible frequencies.
The Glideslope Flag shows when power is lost or the GS signal is too far out or out of range.

Avionics Bending: Haydon Chronometer (Functional Test)

2011-11-02T23:42:00.001-04:00

In two previous postings on the Haydon Chronometer here on the L1011 blog I have gone into detail on the general hardware and the pinout for the Haydon Chronometer. They are actually really neat instruments and not so difficult to control. I have created a very small setup that uses an ATMEL ATmega chip to create the two phase signals with. In the most simple form the clock could really be driven by using either a 60Hz AC source and a few caps for the phase shift or a 555 to create the two phases with. However, I prefer using a micro controller because I wanted to play around with different waveforms. I am excited to see Roberto use the setup as well in his B737-200 cockpit. Here are two images of the clock powered off (the red dot indicates no-power) as well as the backside of the clock with the original Deutsch connector. The connector was cut from the original L-1011 cockpit at about 4 inches after the connector ... so I had to repair the cable with 12 cable splices. I used a twisted shielded pair cable for the phase signals.

Below is a short video that shows the functions of the A. W. Haydon Company Chronometer.

L-1011 Flight Instruments: Source Select (31-13/14)

2011-11-01T21:12:00.000-04:00

It is possible to switch the Captain AS/M and ALT to the F/O's AS/N and ALT indicator and the F/O's AS/M and Alt indicator to the Captain's AS/M and ALT indicator. This is done with the ALTN switches not he Captain and F/O's instrument panels (see yesterday's post).

No switch is provided to change ADC inputs to the autopilot computers.

The ALTN switch pressed first has priority. The light being on in the ALTN switch means the associated instrument is using opposite date. After the ALTN switch is pressed, if the flags remain the instrument is at fault. If the flags disappear, the ADC is at fault.

The L-1011 was certified to use a mixture of INS's and IMEGA data for instruments.

L-1011 Flight Instruments: Instrument Source Select (31-12)

2011-10-31T08:23:00.001-04:00

The instrument source select switches are located at the base of the Captain and F/O's instrument panels. There is a switch for FLT DIR (Flight Director), IAS/M (Airspeed Indicator), ALT/VSI (Altimeter and Vertical Speed), HDG (Heading) and ATT (Attitude Indicator).

L-1011 Flight Instruments: IAS/MACH Indicator (31-10)

2011-10-30T09:00:00.002-04:00

Both IAS/MACH indicators have three fail flags:

OFF - failure of CADC MACH computations.
Vmo - failure of the CADC Vmo computations.
A/S - failure of A/S computations.

A power failure to the IAS/MACH indicator would cause all 3 flags to appear. Instrument switching may be used to restore indications in case of CADC failure. Press the AS/M ALTN select switch and the opposite side CADC data will be used. Switching to the alternate source, of course, will not correct for instrument failure or malfunction.

L-1011 Flight Instruments: Vertical Speed Indicator (VSI) (31-9)

2011-10-29T08:39:00.000-04:00

The vertical speed OFF flag indicates CADC data or electrical power has failed. Pressing the ALT ALTN switch will provide opposite data to the affected altimeter and vertical speed indicator unless the actual indicator failed.

L-1011 Flight Instruments: Barometric Altitude Indicator (ALT) (31-8)

2011-10-28T07:39:00.000-04:00

The most typically installed Altitude Indicator on the L-1011has two fail flags:

SSC - the Static Source Correction feature of the Air Data Computer (ADC) altitude computing has failed. When this flag is displayed, the ADC is still providing altitude data, however, the data is uncorrected.
OFF - there has been an ADC input failure or loss of power to the instrument.

Pressing the ALT ALTN Switch on the pilots panel (located below the HSI) will provide the opposite side data to be the affected altimeter and vertical speed unless the actual indicator has failed.

L-1011 Flight Instruments: CADC1 and CADC2 (31-6)

2011-10-27T19:33:00.003-04:00

The Central Air Data Computer (CADC) 1 provides data to the following instruments:

Capt. IAS/MACH
Altimeter
Vertical Speed
APFD A
No. 1 INS Computer

CADC2 provides data to the following instruments:

APFD B
F/O's IAS/MACH
F/O's Altimeter
F/Os Vertical Speed Indicator
No. 2 INS Computer

All of these ADC instruments are electrically operated with no direct pitot/static input.

History: L1011 Structure Images - Super Guppie

2011-10-27T19:26:00.000-04:00

Here are a few images from the archives. The first image below is an image published by Lockheed in the early 1972 showing the massive size of the Lockheed L-1011 fuselage. The metal structure in the image is a full size mock up of the largest diameter fuselage section:

The two images below show the left wing of N1011 and shows the leading edge Slats and the trailing edge Flaps very well. And a really neat historic image of an L-1011 wing being loaded into a Super Guppie.

L-1011 Flight Instruments: Central Air Data Computer (CADC)

2011-10-26T12:25:00.000-04:00

The L-1011 has a fully electronic Air Data Computer system that replaced many analog systems except for the standby instruments. All in all, the flight instruments are driven by:

Air Data Computers (ADC)
Attitude Reference System
Heading Reference System
Instrument Comparator
Radio Altimeter

A total of four pitot/static probes are mounted on the L-1011.

Two on the Captain's side (Capt. top, F/O lower).
Two on the F/O side (F/Os top, Capt. lower)

Each probe senses both pitot and static pressure. There are no connections between pitot inputs. Cross over static sensing is provided for balance pressure sessions. Captain's and F/Os total air temperature probes are also provided.

All instruments which have traditionally been pitot/static are operated electrically by air data computers (ADC). ADC#1 provides data to the Captain's instruments and is sourced from the AC STBY BUS. ADC#2 provides data to the F/O's instruments and is powered form the Number 2 AC BUS. ADC#1 uses the Captain pitot/static and air temperature system and ADC2 uses the same system from the F/O. The basis inputs into to the ADC are not switchable, however, the ADC outputs can be switched between sides.

L-1011-1 Dimensions (Part 2)

2011-10-25T19:01:00.001-04:00

Here are more details of the Lockheed L-1011-1 airframe. The cross sections should make it relatively easy to model the L-1011-1 for a good simulator physics model. There are more detail sections to come. This posting shows the details at various frame stations. The images are taken from a Lockheed Engineering publication published in the mid 1970s. Click the individual images to enlarge them and full them in full resolution.

Fuselage cross sections A, B, C and D.

Fuselage cross sections E, F, G, H, J and K.

The cockpit section.

L-1011 Flight Controls: Active Controls Load Distribution (27-51)

2011-10-25T08:06:00.002-04:00

In the illustration above the dotted line shows the basic wing lift design load distribution of the L-1011 wing. the solid line shows the redistribution produced by symmetrical upwards deflection of outboard ailerons. Both load distribution lines are for the same structural design wing lift but the redistribution line show how aileron deflection moved the center of pressure inboard thus lowering the wing root bending moments. During cruise, aileron deflection would be minimal.

the Active Control System (ACS) uses outboard ailerons symmetrical deflection to relieve wing loading. Aileron deflection is controlled by accelerometer and sensor signals delivered to the ACS computer and from there on to the aileron servo. The computer provides the following functions:

Maneuvering Load Control (MLC) by redistributing air loads caused by maneuvering air gusts inward span wise toward the wing root.
Elastic Mode Suppression (EMS) - Reduces vibrations along the wing in response to the wings natural bending vibration frequency.
High Lift Control (HLC) or wing tip relief when in the high lift, high drag flaps and slats extended configuration. (Both outboard ailerons will be up 8º).

History: Test Flight Images

2011-10-25T07:54:00.001-04:00

Two more images showing N1011 and N301EA during test flights. The images are part of photographs released in the 1970s by Lockheed-California. The images are not dated but are, like most of the other images I have, from the archive of Don Pierce.

The image below shows N1011 repainted to a new demo scheme with the words "Advanced TriStar" on the tail. This is the paint scheme N1011 remained in until it was scrapped in 1992. You can see N1011 in its original paint scheme here.

L-1011-1 Dimensions (Part 1)

2011-10-24T08:39:00.002-04:00

A few of you simulator builders have asked me if I could provide better measurements of the L-1011. Thanks for the interest! I have found a few detailed images that show the dimensions of the L-1011. The one pictured here is for that -1 model. Enlarge the image to read the measurements better.

L-1011 Flight Controls: Active Controls -500 (27-50)

2011-10-24T07:39:00.000-04:00

Here is something that is only relevant to the -500 model of the Lockheed L-1011. The active control system provides a means of relieving loads caused by the increase in wing span on the -500. Load relief is accomplished by outboard ailerons symmetrical deflections programmed by the Active Control System (ACS). The ACS is dual channel with either channel capable of performing the proper programming of aileron deflections. The system uses a revised outboard aileron servo with 2 ACS series servos (1 and 2) mounted to each outboard aileron servo . Triple accelerometers located in each wing tip and forward cargo compartment ceiling (9 total) provide the acceleration signals, and 3 impact pressure (Q) sensors provide airspeed affect for gain scheduling.

L-1011 Flight Controls: Flaps and Slats (27-46)

2011-10-23T09:31:00.001-04:00

The L-1011 has four panels of double slotted Fowler flaps on the trailing edge of both wings. The flap system is hydraulically powered by a Power Drive Unit located in the hydraulic service center. This unit drives torque tubes which in turn power the flaps through recirculating ballscrew actuators.

The slat power drive unit is powered by hydraulic systems A and C same as the flap system and is located in the left wing root outside the fuselage pressurized area. Torque tubes run the length of the leading edge.

Flap and slat systems both are controlled through a single flap/slat handle located on the center console right side. Selection of 0º or 4º flaps causes flaps to extend to the selected 4º while slats extend completely. Flap handle movement is transmitted to both the slat Power Drive Unit (PDU) and the flap PDU through cable runs, rods and links. Cable break detectors monitor for broken cables. A broken cable shuts down the PDU by removing hydraulic power from the two hydraulic driven motors and the spring applied, hydraulically released, brake.

Both the flap and slat PDUs are powered by two hydraulic systems, A and C. Flaps/Slats operate normally with only one hydraulic system powering, but movement of the surfaces is slower. The PDU hydraulic motors, through gears, drive torque tubes along the length of the wing on both the front and rear spars. As the torque tubes rotate, they drive recirculating ballscrew actuators. The actuators, one for each slat panel , and two for each flap panel, drive the respective surface up and down on rigid tracks attached to the spars.

For assemblies, one on the end of each torque tube, contain a position transmitter that drives the respective slat indicator needs, and flap indicator tapes. The assemblies also contain spring applied mechanical brakes and asymmetry detectors. The detectors count torque shaft turns at both ends and thereby monitor for asymmetry.

Should an asymmetry be detected, the mechanical brakes at the ends of the Torque Tubes Lockup. Also the PDU hydraulics are shutoff applying the PDU brake and the system is lowed in position stopping any asymmetry well within the aileron control limits.

L-1011 Flight Controls: DLC and Glide Slope (27-41/44)

2011-10-22T11:03:00.000-04:00

The image above shows the aircraft on approach path. DLC spoilers 1, 2, 3 and 4L and 4R are up to null position of approximately 10º up. The spoilers will operate up to 20º or close to 0º from the null position with session of Pilot or Autopilot pitch inputs.

Once panels have moved to a position from the 10º null position they drift back to the null position ready for the next excursion.

If the aircraft moves above the glide slope, DLC commands spoilers 1, 2, 3 and 4 open to 20º reducing approximately 10% of lift. 400,000 lb. of weight results in a -40,000 lb. of lift reduction. The airplane returns to approach path with only a minor pitch change. This provides increased passenger comfort.

If the aircraft has drifted below the glide slope, pitch input causes the close the increasing lift and the aircraft flies back into approach path with only minor pitch changes. DLC serves one additional important function: its use reduces the size of the landing touchdown zone scatter. Thereby improving category III autoland precision.

The image above shows the Surface Position Indicator with DLC spoilers 4 and right 2 indices traveling also the speed brake lever traveling in the DLC range in response to pilot commanded stabilizer movements.

DLC automatically disengages under any one or all of the following conditions:

Stall Warning
Go-Around Switch Activated
Any two Throttles Advanced
Flaps Retracted less than 30º
Pilot-mnaual Override of Speed Brake Lever
Pilot Assist Disable Switch Pressed
System Failures

History: L1011 Under Floor Galley and 1st Class Cabin (Pressphoto)

2011-10-21T10:03:00.001-04:00

One of the rather unique things about the Lockheed L-1011 was the very innovative under floor galley. As the picture below shows the galley was quite roomy, however, did not have quite as much headroom as the picture gives illusion to. The two doors in the back of the image are the two electrical elevators connecting the cabin to the underfloor galley. The image is part of an early press release deck published by Lockheed in the early 1970s.

The first class cabin and the economy cabin was divided by a movable set of walls for easy reconfiguration. What the picture below shows is the remarkable ceiling height in the L-1011 cabin which is even more pronounced by the fact that the L-1011 pictured did not have the center luggage bins installed.

Great picture of N301EA in a left bank showing the very clean design of the aircraft underside.

L-1011 Flight Controls: Direct Lift Control (DLC) (27-39)

2011-10-21T08:01:00.001-04:00

Spoilers 1, 2, 3, and 4 are used for Direct Lift Control (DLC). The spoilers are driven automatically through the DLC/AGS servo. Here is the DLC engage logic:

Flaps are set to more than 30º
At least two throttles are below MCT
At least two for the throttles are not in reverse.
There is no Airplane On Ground (AOG) signal received
The airplane is not in go-around mode
There is no stall warning
The DLC/AGS channels are powered and OK

The DLC servo that controls spoiler panels 1, 2, 3 and 4 assists in pitch control by reducing the amount of pitch attitude change required to peek the airplane in the "slot" once landing flaps are selected. DLC servo inputs cause the spoilers to travel thereby increasing or reducing lift.

The spoiler handle located on the throttle quadrant follows all DLC inputs providing an indication to the crew of system operation.

History: N1011 Test Flight Images

2011-10-20T12:47:00.000-04:00

Here are a few really cool shots of N1011 during test flights. The images are pictures published by Lockheed for press releases in the very early 1970s.

The image below shows Lockheed's N1011 with the still TWA painted N3001 in a little bit of L-1011 formation flying. The aircraft was later re-pained to Eastern Air Lines colors and sold to Eastern.

Below shows N1011 chased by what appears to be N8544, however, it's hard to tell from the picture and the FAA registry for N8544 is no longer known.

They are really neat shots of N1011 and again, they are from the archive of Don Pierce. By the way, just as a piece of useless trivia, N1011 (as a FAA registration) has gone from this iconic aircraft to being registered to a Sea Ray kit plane witch was destroyed in 2000 and is currently registered to a Cessna T210N.

L-1011 Flight Controls: Spoiler Roll Assist (27-38)

2011-10-20T07:56:00.000-04:00

When the Flaps on the L-1011 are set to 4º or more, spoilers 2, 3, 4, 5 & 6 assist roll on the up aileron or down wing in the turn. Travel can be as much as 40º up on the spoiler for roll assist. What's important to remember is that the spoilers are up with the aileron. They are dwelled or silent on the other wing.

History: Early Lineup N1011, N3001 and N301EA

2011-10-19T07:55:00.000-04:00

Pictured is a line-up of the first three L-1011s produced. The picture is a Lockheed press image from Don's archive but was not dated. I would assume that it was taken in either 1971 or 72? The image was taken at Lockheed's Palmdale facility in California and it shows, from front to back, N1011, N3001 painted in TWA colors and N301EA painted in Eastern Air Lines colors. N1011, the one in the very front of the picture ended up becoming a movie prop for Disney before it was scrapped. At least portions of the cabin and the cockpit section of N1011 got rescued and are now on display as a cut-off at the Delta Air Transport Heritage Museum in Atlanta. Delta re-painted the prototype aircraft to Delta colors. I am still amazed that Lockheed did not preserve the iconic N1011 as a museums item, but I guess after Lockheed pulled out of the commercial market holding on to the commercial aircraft legacy was not that important.

L-1011 Flight Controls: Speed Brakes - Flaps Up (27-37)

2011-10-19T07:36:00.001-04:00

A rear view of the airplane shows spoilers L&R1 and L&R2 & 3 in their travel limited position with the corresponding Surface Position Indicator (SPI) indices. The inside right travel for number 2 & 3 spoilers is 30º while spoilers 4, 5 and 6 are up the full 60º speed brake travel. Also, number 1 spoilers L & R have no indication of the 20º up on the instrument in the image.

The B & D labeled indications on the SPI represent hydraulic systems powering the limiter actuators.

History: First Flight (Autographed Press Photo)

2011-10-18T12:42:00.001-04:00

This picture is from the archives of Don Pierce. The photo shows the takeoff of Ship #1 on its maiden flight. The picture is signed by the four persons who were the crew on-board. Henry Baird (Hank) Dees was the pilot, Ralph (Coke) Cokeley was the copilot, Rod Bray was the Flight Test Engineer and Glenn Fisher was the Flight Engineer. Coke had also been a pilot for Boeing on the 747 during its flight test program.

There is a lot of good writing on the maiden flight here at this link Building The TriStar, however, over the years (the article is from 2003) it appears that the image links have gone bad.

L-1011 Flight Controls: Spoiler System (27-35)

2011-10-18T07:53:00.003-04:00

The Lockheed L-1011 has six flat panels on each wing forward of the flaps. The panels hare hinged on the forward end and are driven up into the airstream by a single hydraulic actuator for each panel. The panels are numbered 1 to 6 from the fuselage toward the wing tip.

Here are the spoiler ranges for various flight conditions:

Flaps-Up - Speed Brakes
1 2 3 4 5 6
20º 30º 30º 60º 60º 60º

Flaps 4º to 33º - Speed Brakes
1 2 3 4 5 6
N/A 60º 60º 60º 60º 60º

Roll Augmentation

1 2 3 4 5 6

N/A 40º 40º 40º 40º 40º

Direct Lift Control (DLC)

1 2 3 4 5 6

10º 10º 10º 10º N/A N/A

Auto Ground Spoiler

1 2 3 4 5 6

60º 60º 60º 60º N/A N/A

The spoilers have four modes of operation. They are:

speed brakes flaps up which are conventional
roll augmentation to assist aileron when flaps are extended
DLC during approaches and
Automatic Ground Spoilers which operate on landings and rejected takeoffs.

The System comprises of a speed brake lever either manual or boosted through ta DLC/AGS servo powered by hydraulic systems A and B.

From the lever and servo, cable runs and roll systems deliver pilot or servo inputs to units called mixers located in the wheel wells. The mixers receive flap position and aileron position inputs and thereby shift accordingly setting up linkages causing the spoiler panels 2, 3 and 4 to work in the various modes.

Another pair of right and left units called selectors located on the rear spars just inboard of the outboard ailerons receive pilot, flap and aileron inputs and schedule spoiler 5 and 6 right and left respectively from their two modes of operation. Number 1 spoiler control linkage is a bit different in that it uses a solid controller cable for inputs which cause it to work in its two modes.

History: LTU Maintenance Fire MSN 1114 in 1991

2011-10-17T08:09:00.001-04:00

20 years ago, in 1991, a German LTU L-1011-1 (MSN 1114) caught on fire during a routing maintenance activity. The aircraft interior ignited during carpet replacement Thursday June 27th 1991. The aircraft was actually parked inside the LTU hangar as the fire erupted but the maintenance team on site managed to push the aircraft outside prior to the arrival of the fire engines because fortunately the tug was still attached to the aircraft. The intense heat of the interior fire caused the roof to melt and collapse. The aircraft had been in services for 16 years at the time of the fire and was previously register as N10115 with PSA in the US but then became D-AERI with LTU.

These two images are from the archive of Don Pierce who, at the time of the fire taught a L-1011 systems class for LTU in Germany. There where minor injuries amongst members of the maintenance crew, however, as dramatic as the pictures look, lucky enough there were no fatalities and no other damage to LTU property as a result of this maintenance fire. However, MSN 1114 was as total write-off.

L-1011 Flight Controls: Aileron Control System (27-33)

2011-10-17T08:09:00.000-04:00

Conventional wheels connected by roll disconnect. Two control cable paths, one on each side of the fuselage.

The main difference between the two control paths are - left path or Captain's side is the main or primary control path due to system design and lost motion device at bottom of the F/O column before inputs to right control path. F/O inputs cross over through Captain's; or primary path, under normal operation. Both paths incorporate roll monitor bungees. Also a bungee between inboard ailerons. No monitor in aft interconnect bungee between inboard ailerons. Conventional manual trim wheel on aft ENP of center console through cables to trim actuator in left primary or master aileron path trims feel forces, as in stabilizer and rudder trim systems.

Now continuing with primary path to left inboard aileron master servo we see that three hydraulic systems A, B & C power the aileron actuators controlled through the servo by pilot inputs. From the master inboard aileron one path goes to the spoilers input and on to the outboard aileron directly off inboard aileron movement to the outboard aileron servo. The outboard aileron is powered by two hydraulic systems B & C controlled by the servo.

Another control path from the left inboard, or master aileron movement crosses through the fuselage and aft interconnect bungee to the right inboard aileron servo which controls the three right inboard aileron actuators powered by hydraulic systems B, C & D.

From the right inboard aileron the primary control path continues directly from inboard aileron to the right wing spoilers and to the outboard aileron servo which controls the aileron's two actuators power by Hydraulic Systems B & D. Note again the hydraulic systems do not cross over as they power the ailerons.

L-1011 Flight Controls: YAW SAS in Parallel (27-31)

2011-10-16T15:33:00.001-04:00

Parallel mode provides runway alignment, rollout guidance, and engine out go-around capability during autopilot operation. Parallel mode is different in the the rudder pedals are now connected through the servo and the pilot receives rudder movement feedback. The YAW SAS system now also has the same authority as the Pilot or 30º. Manual inputs may be applied through the rudder pedals to override the servo, but ruder pedal forces will be approximately one hounded pounds of pressure or more.

History: Frank Borman Test Flight (Press Image)

2011-10-16T15:26:00.001-04:00

Don Pierce sent me a great picture from his archive. The picture is an original 8 1/2 x 11 black and white photograph released by Eastern Air Lines in French. The picture shows the NASA Astronaut and Eastern Air Lines CEO Frank Borman on the left and Lockheed L-1011 test pilot Henry Baird (Hank) Dees on the right. The picture was taken onboard the prototype L-1011 used for flight tests conducted together with Eastern and Frank Borman.

The original caption of the picture reads:

Frank Borman, Vice-Président du Groupe Opérational d'Eastern Air lines, après avoir piloté l'impressionnant "TRISTAR" et effecuté en outre un essai concluant de "touch and go" consistante à prendre contact avec le sol, puis à redonner des gaz en bout de piste, simulant le cas d'un atterrissage "trop court", a déclaré:

"c'est un avion pour vrais pilotes, sa parfaite stabilité en vol fait présager qu'il deviendra un appareil très populaire auprès des usagers".

Aujourd'hui l'appareil est au BOURGET. L'expérience technique de Frank Borman s'est révélée concluante puisque nous avons le loisir de présenter l'appareil au milieu de toutes les autres nouveautés du Salon.

Here is my best effort translation since I don't speak any French (per Google translate):

Frank Borman, Deputy Chairman of the Operational Group of Eastern Air Lines, after having driven the impressive "TRISTAR" and also conducting asuccessful trials of "touch and go" to make consistent contact with the ground and to restore thrust, simulating the case of landing "too short", said:

"It's a real airplane for pilots, with its perfect stability in flight I predict that it will become a very popular vehicle among users."

Today the aircraft is at Bourget. The technical experience of Frank Borman proved conclusive since we have the opportunity to present the aircraft in the middle of all the other novelties of the show.

There are some interesting details on the cockpit panel of the test aircraft (which I assume was N1011 ... however, the picture does not identify the aircraft).

There is is no pitch or auto throttle panel yet, actually there are no autopilot elements all tighter.
The place of the APFDS disconnect panel is taken by a clock.
The APFDS Modes panel has a clock in place of the modes annunciator.
There are no TGT instruments as part of the main instrument cluster.
The annunciator is displaced to the right in this prototype panel and the standby instruments are replaced with a number of other unknown instrument.
The pilot side main instrument panel has a number of extra instruments that did not become part of the final production version. They are hard to make out from this picture.

The overhead panel on the test model is also missing a number of production panels in this image. For example

there an unknown panel with no light plate and a few cutouts. I suspect, that the panel did not actually do anything but was placed as a placeholder and
there is no Rudder Limiter and Mach Feel panel quite yet.

Avionics Bending: Voltmeter DC Indicator (Pinout)

2011-10-15T14:24:00.003-04:00

The L-1011 Electrical System panel has both a AC as well as a DC voltmeter. The pinout shown here is for the DC Voltmeter.

The instrument shown above is the original Instrument used on the L-1011. However, the way the back illumination worked on the L-1011 electrical and hydraulic gauges caused a lot of yellowing due to heat exposure. Instruments used on Boeing Aircraft like the B747 with the same pinout did not experience that because the illumination of the gauge is significantly different. Below is the B747 instrument using exactly the same pinout:

Here is the pinout:

Pin	Pin Assignment	Value
1	+5V Lighting	0 .. +5DCV
2	Instrument Lighting GND	GND
3	Instrument Casing GND	GND
4	DC Source GND	GND
5	DC Source	0 .. +40VDC

L-1011 Flight Controls: YAW SAS in Series (27-30)

2011-10-15T09:44:00.000-04:00

As described in the last posting, the YAW SAS has two modes of operation. The firs tis called "series" and provides full time yaw damping and turn coordination (yes, once you fly the big guys you can forget the "step on the ball" rule your flight instructor hammered into your head ... just kidding). Series means that the YAW SAS system is providing electric inputs to the rudder servo, but motion is not supplied to the rudder pedals - they remain in neutral. Manual inputs may be applied through the rudder pedals to override the servo with normal pedal forces.

As noted in Controls and Indicators, two channels of YAW SAS are provided for redundancy. The switch lights are on the FCES panel. Series YAW SAS has 8º of rudder authority.

L-1011 Flight Controls: Rudder (27-28/29)

2011-10-14T08:54:00.003-04:00

To get all the details, you might want to enlarge the picture above. The Rudder, on the L-1011, is a large single surface with servo and actuators near the lower end. There are no tabs on the L-1011 rudder. The rudder is fully hydraulically powered by the A, B and C hydraulic systems.

The rudder is powered by two dual-tandem actuators (see image above) which operate as three in depended actuators and a controlling triple servo module. Hydraulic system A, B or C are capable of providing full rudder operation. Hydraulic power is manually controlled by the hydraulic limiting system.

The rudder servos are mechanically operated by the rudder peals through cables or electrically signaled by the Yaw Stability Augmentation System (YAW SAS).

Rudder Trim

Pilot inputs can be made from either set of rudder pedals but control is provided by a cable run coming form the Co-Pilot's rudder pedals. Rudder trim is mechanical and simply establishes a new neutral position for the rudder feel mechanism. Rudder trim displease the ruder pedals.

Surface Position Indicator (SPI)

Top of the SPI, single indicator shows rudder position to 30º right and left.

Rudder Hydraulic Limiter

The limit is controlled via a switch on the overhead that is normally latched in dark/no lights position. Amber "PUSH" with malfunction or loss of system pressure. White "OVRD" is switch pushed and unlatched. Powers back all available systems.

Rudder Power OFF Switch

The Rudder Power OFF switch removes all power from the rudder. This also powers down the YAW SAS.

YAW SAS

The YAW SAS has two mods of operation. The first is called series and provides full time yaw damping and turn coordination. Series means that the YAW SAS is providing electric inputs to the rudder servo, but motion is not supplied to the rudder pedals - they remain in neutral. Manual inputs may be applied through the rudder pedals to override the servo with normal pedal forces. In this mode the YAW SAS has only 8º of authority over the rudder. The second mode is called parallel mode and provides runway alignment, rollout guidance and engine out go-around capability during autopilot operation. Parallel mode is different in that the rudder pedals are now connected through the servo and the pilot receives rudder movement feedback. The YAW SAS now also has the same authority as the Pilot ... or the full 30º. Manual inputs may be applied through the rudder pedals to override the servo, but rudder pedal forces will be approximately one hundred pounds.

L-1011 Flight Controls: Stick Shaker (27-27)

2011-10-13T15:31:00.000-04:00

A stall warning is provided by stick shakers which vibrate the control columns when airspeed drops to one hundred seven percent (107%) of the stall speed. the system is normally operated with both stall warn switches latched in. This will cause the first officer's, or number 2 stick shaker, to operate should a stall occur or the test switch be pressed while on the ground. The stick shaker will be felt in both control columns. The Captain's stick shaker only operates when number two system is unlatched/deactivated.

Each channel is controlled by an FCES Panel pushbutton switch. Inline monitoring is provided for sensor and power fault detections. Faults detect will annunciate an FCES Panel "FAIL" message, but will not automatically disconnect the affected channel. The pilot in all cases of indicated failures on the channel control switches, should disengage the faulty channel by depressing the appropriate switch. The second channel, whenever normally engaged, remains capable of providing stall waring.

Avionics Bending: ATM Tach Indicator (Pinout)

2011-10-12T18:59:00.001-04:00

The L-1011 has an Air Turbine Motor (ATM) that can directly pressurize the B and C Hydraulic systems. The indicator shown in this pinout displays the RPM of the ATM and is located on the L-1011s' Hydraulic System panel:

Below is the schematic for the ATM Tachometer Indicator:

Below is the pinout summary:

Pin 1: 5V AC Lighting
Pin 2: 5V AC Lighting
Pin 3: RPM Level in +
Pin 4: RPM Level in -
Pin 5: Chassis Ground

L-1011 Flight Controls: Stabilizer Control System (27-24)

2011-10-12T08:04:00.001-04:00

To see all the described entails below, you might want to enlarge the picture above.

Conventional control columns operate through independent cable systems to control the two dual Hydraulic Servo Units. Each servo unit contains two hydraulically independent control valves. Each of the 4 servo units are supplied by a separate hydraulic system. Thus, two dual control and 4 hydraulic actuators provide maximum protection against system failure. Feedback links between the servos and the stabilizer signal position of stabilizer to the servos.

Stabilizer Servo Interconnect (Auto Transfer to System B.)

A mechanical interconnect device between the A/B and D/C stabilizer servos prevent shutdown of all 4 servos simultaneously. The unit allows only paired servos to be depressurized at any onetime. The mechanical device gives the B Servo priority. Since the Ram Air Turbine (RAT) will supply pressure the the B Hydraulic System in case of loss of all other sources, it is logical to have a mechanical interlock which gives the B Stabilizer Servo priority.

The separate control paths from the Captain's and Co-Pilot's stations are coupled at both the forward and the aft ends of the aircraft by the pitch disconnect mechanism and the aft coupler. The Pitch Disconnect can be separated manually by using the T-handle in the center console. The Aft Coupler is disconnected electrically and automatically if both servos on one side are turned off. A pitch monitor is used to continually monitor the Pitch System for possible jams. Each Stabilizer Servo has two switch lights located on the Primary Flight Control System (PFCS) panel which display a loss of hydraulic pressure or a jam condition by illuminating INOP.

Bungee cartridges, one in each control path and one int he Aft Coupler path act as solid links during normal operation. If either control path should jam, Pilot forces exerted on the control path will apply breakout forces to the affected bungee. Switches attached tot he bungee will sense the breakout and signal the monitor system the fault condition which then illuminates the PUSH lights on the PFCS.

Pitch Trim/Feel

The Pitch Feel and Trim Force System is comprised of two units, one in each cable path which provides artificial feel forces and trim inputs for the Pilot and reaction forces to the autopilot. The Captain's path has an electric unit one the Co-Pilot's path has a mechanical unit. These feel/trim unit are coupled with a Trim Synchronizing Shaft so any inputs into one side will be transferred to the other. Manual trim inputs are made to the mechanical trim unit in the Co-Pilot's side cable path. Electric trim input go to the two electric motors in the Electric Path. These inputs are kept synchronized by a shaft connecting the two units. Loss of one channel reduces Electric Trim Rate to half normal rate.

Mach Trim

The Mach Trim system is a two-channel system as well, one is active - the other one is standby. The system provides speed stability compensation in the pitch axis trim when operating under manual control in the high speed region. Engagement of the autopilot does not disable the Mach Trim system function. Mach Trim can be overridden by electric trim, manual trim and autopilot trim inputs. Mach Trim remains in the existing condition should both channels fail.

The two channel switches located in the FECS overhead panel provide the Mach Trim control and fault annunciators.

Mach Feel

The Mach Feel system is a two-challen active-standby system which operates together with stabilizer trim angle and Mach number to provide pitch control force changes in stabilizer effectiveness as a function of Mach.

The system normally controls one of two electrical motors which are integrated into the pitch feel/trim mechanism. The pitch control force gradients are scheduled from Mach data derived from the two Central Air Data Computers (CADC). Engagement of the autopilot does not remove the function of the Mach Feel system.

The meter on the Mach Feel panel indicates position status of the Mach feel system, calibrated in Mach. The feel system position meter also provides pilot indication of proper system operation. The indicated Mach number should match the Mach number on the Airspeed Indicator.

Autopilot Servo

The two autopilots powered by hydraulic systems A and B provide pitch inputs to the Control Path through the Aft Cross Tie. Trim follow-up is brought the mechanical Feel/Trim Unit. Therefore, the Stabilizer servos receive the input signals the same way from the autopilot as they would from pilot inputs. The Electric Trim Thumbwheel on the control column, however, is de-energized when the autopilot is in operation, except in Control Wheel Steering (CWS) mode when then Pilot applies the necessary force to the control column.

Avionics Bending: ECS Temperature Indicator (Pinout)

2011-10-11T18:56:00.000-04:00

The L-1011 ECS temperature indicator is part of the ECS monitoring panel. There are actually two temperature gauges on that sub panel, one to measure various ECS system temperature outputs and the other to measure cabin zone temperature with. The one described here in this posting is the one displaying ECS system temperatures.

The schematic below is in fact for the Cabin Temperature gauge, however, the ECS Temperature indicator is built exactly the same way.

The pinout of the instrument is rather simple.

Pin 1: 5V AC Lighting
Pin 2: 5V AC Lighting
Pin 3: 115V 400Hz Power In
Pin 4: 115V 400Hz Lo
Pin 5: Temperature Sensor +
Pin 6: Temperature Sensor -

L-1011 Flight Controls: Flying Stabilizer (27-23)

2011-10-11T09:10:00.002-04:00

The L-1011 has a flying stabilizer that is powered by all four hydraulic systems. However, any one of the hydraulic systems alone is capable of controlling the airplane. The advantages of a flying tail/stabilizer are:

No mistrim problem
No stalling drive mechanisms
The elevator is mechanically slaved
Non-linear controls
Column remains in position

The feeling on the column is created by springs. There is no direct force feedback, it is created through the stabilizer position and the Mach number. Everything is done fully by hydraulics, there is no electrical power required.

Avionics Bending: Flap Position Indicator (Pinout)

2011-10-10T18:25:00.001-04:00

The flap position indicator is actually a quite sophisticated instrument. Fully synchro driven it not only requires synchro input signals, but it also acts as the 26V 400Hz source for what would have been the synchro transmitters attached to the trailing edge flaps (see right hand side of the larger schematic).

The image above shows the Flap Position Indicator powered off but with back illumination on. In this state the tapes roll about half way down the instrument to the "OFF" indicators. The two tapes are really independent from each other and only share a few common logic pieces. All of the motors and position synchros are unique to each tape.

Below is the full schematic for the L-1011 flap position indicator:

The complete pinout for the L-1011 Flap Position Indicator:

Connector	Pin	Function
Sort	Sort	Sort


P1	01	Chassis Ground
P1	02	115V 400HZ AC Power Lo
P1	03	LE TRANS Annunciator Lo (5V)
P1	04	Instrument Ground
P1	06	26V 400Hz Output
P1	07	5V Instrument Lighting Hi
P1	08	5V Instrument Lighting Lo
P1	10	Left Flap Tape Synchro Input X
P1	11	Right Tape Synchro Input X
P1	12	LE TRANS Annunciator Lo (5V)
P1	14	LE EXT Annunciator Lo (5V)
P1	15	LE EXT Annunciator Hi (5V)
P1	16	115V 400Hz AC Power Hi
P1	17	26V 400Hz Signal Ground
P1	21	Left Tape Synchro Input Y
P1	22	Left Tape Synchro Input Z
P1	23	Right Tape Synchro Input Z
P1	24	Right Tape Synchro Input Y

L-1011 Flight Controls: Slat Monitor Panel (27-22)

2011-10-10T08:13:00.004-04:00

The Slat monitor panel is located in the the upper flight engineer panel. The panel has the following components:

14 green lights, one for each slat.
"ON" switch on the panel arms the green lights.
A Travel Indicator with two needles. One for right, one for the left wing. There is also an OFF flag that shows loss of instrument power.
"LOCK" switch light with LOCK1 and LOCK2 positions.

There are also a number of annunciators on the flight engineer's annunciator panel:

LE SLAT/LOCK light - illuminates with slat asymmetry.
ASYM/DET FAULT light - illuminates with failure of asymmetry detector.
TE FLAP/LOCK light - illuminates with flap asymmetry fault.

Avionics Bending: RAM Position Indicator (Pinout)

2011-10-09T11:33:00.003-04:00

The L-1011 has three air-conditioning packs. Each of the Packs has a RAM Air intake that can be controlled an Turbine By-Pass Valve that can be controlled from the ECS panel. In essence, what the instrument indicates is the valve posting from all the way closed to all the way open. These valves are either driven automatically by the climate control system or they can be operated by manually with the monetary switches located below the indicators.

The instrument again is a rather simple indicator and here is the schematic for it:

By the way the schematic and the pinout is identical for the Turbine Bypass indicator.

Here is the pin-out:

Pin A: 5VAC Lighting
Pin B: 5V AC Lighting
Pin C Instrument and Sensor Power
Pin D: Pot-H
Pin E: Pot - Wiper form Sensor Side
Pin F: Pot-L

L-1011 Flight Controls: Rudder and Aileron Manual Trim (27-21)

2011-10-09T10:02:00.000-04:00

On the L-1011 neither the Rudder nor the Aileron trim is electronic, they are considered conventional. The Aileron is trimmed by rotating the trim wheel that is protruding from console to either Left Wind Down (LWD) or Right Wing Down (RWD). The will is marked in 10 units which equals to 7º of authority.

The Rudder is trimmed by rotating the when on top of the the rear console. This wheel also contains a crank. The Trim authority for the Rudder trim is 10º left or right.

Avionics Bending: Pack Flow Indicator (Pinout)

2011-10-08T12:10:00.000-04:00

The pack flow indicator shows the amount of cubic feet of ear being cycled through the packs per minute. The pack selector to the right selects which pack flow is being indicated.

The instrument is very basic and only uses four pins, two for instrument lighting and two for the DC indicator value.

Here is the instrument pinout:

Pin 1 - 5V AC Lighting
Pin 2 - 5V AC Lighting
Pin 4 - Pack Flow GND
Pin 5 - Pack Flow Value (+)

L-1011 Flight Controls: Pitch Trim Wheel Indicator (27-20)

2011-10-08T09:27:00.001-04:00

End view of the Manual Trim Wheel. The Indicator (arrow head on the dial) moves with the electric or many trim inputs. The electric trim inputs are on the pilots' and first officers' control wheels. The takeoff trim range is indicated and is between 1.3 - 7.8

L-1011 Flight Controls: Center Console Flight Controls (27-19)

2011-10-07T18:12:00.004-04:00

The L-1011 center console has a number of flight controls besides the thrust levers. Here is a summary of those controls:

Flap/Slat Lever on the right hand side - for selecting various flap positions (see yesterday's Flap Position indicator posting)
Speed Brake Lever on the left hand side - for manual spoiler/speed brakes. This lever also travels automatically with DLC/AGS. The lever also has one switch and two indicator lights. The disable switch is to unpower boosted spoilers and the two amber DLC/AGS spoiler channel disable indicators. The two lights come on when disabled through the handle switch.
Pitch/Roll Disconnect Handles - located in the left and right forward corners of the console illuminate amber when pulled and rotated to disconnect the two control columns.
Stabilizer Manual Trim Wheels - to the left and right of the console.

Avionics Bendig: Hydraulic Fluid Level Indicator (Pinout)

2011-10-06T21:22:00.002-04:00

The Hydraulic Fluid gauges are located in the top portion of the L-1011 Hydraulic System panel. This particular instrument came in a number different version. One that looked like the instrument in the picture below:

And another that simply had a large red and a large green field painted on the face of the instrument indicating "good" or "bad" hydraulic fluid level.

The schematic for the instrument is really simple:

Here is the instrument pinout:

Connector	Pin	Function
Sort	Sort	Sort


P9	1	5V AC Instrument Lights
P9	2	5V AC Instrument Lights
P9	3	Fluid QTY Level Signal - DC IN
P9	4	Fluid QTY Level Signal - DC GND
P9	5	N/A
P9	6	N/A
P9	7	Chassis Ground

L-1011 Flight Controls: Flap Indicator (27-17)

2011-10-06T16:14:00.001-04:00

The L-1011 had at least two different variants of the Flap Indicator. The variants depended on the type of L-1011. The one in this posting is from a -500 that has a different flap range than the -1 or -100 for example. So you might see a different flap indicator in other postings here on the blog:

The Flap Indicator is located on the right side of the Pilots' center instrument panel above the landing gear lever. The instrument has two tapes - one for each set of wing flaps left and right. Flap positions are are:

0º/UP
4º (maximum extend speed 250K)
10º (maximum extend speed 230K)
14º (maximum extend speed 225K)
18º (maximum extend speed 220K)
22º (maximum extend speed 215K)
33º (maximum extend speed 200K)

The OFF Flag shows loss of power (on other indicators the tapes will roll half way to an OFF marker). The SLAT Lights are indicators for the status of the leading edge slats

RED SLAT light - will illuminate when the slats are not in position
GREEN LE/SLATS light - indicates are slats are fully extended
GREEN FLASHING LE/SLATS light - the slats are in transit

L-1011 Flight Controls: Surface Position Indicator (27-16)

2011-10-05T07:46:00.000-04:00

The surface position indicator is located on the main instrument panel. It indicates the position of the:

Rudder
Stabilizer
Ailerons, inboard and outboard (the button switches from inboard to outboard)
Spoilers
DLC
Auto Pilot
Mis-Trim Flags

L-1011 Flight Controls: Mach Feel and Rudder Limiter Panel (27-15)

2011-10-04T09:04:00.001-04:00

The L-1011 Mach Feel/Rudder Limiter Panel is located on the overhead panel.

MACH FEEL

Two Channels
Mach Feel Force Comparison indicator.

RUDDER LIMITER

Override switch to power all available hydraulic systems back to rudder.

Typically there is also a chart of hydraulic rudder limiting for various speed conditions.

L-1011 Flight Controls: Primary Flight Controls Systems (27-14)

2011-10-03T08:16:00.001-04:00

The Primary Flight Controls Systems (PFCS) panel on overhead forward of FCES.

The controls on the panel contain:

Switches for Pitch and Roll Monitors (two channels each).
Rudder Power (Off Switch)
Stabilizer Servo Controls
Aileron Controls
Spoiler Controls

L-1011 Flight Controls: FCES Panel (27-13)

2011-10-02T08:39:00.000-04:00

L-1011 cockpit controls have a conventional layout. There are two control columns with wheels, rudder pedals for both the captain and first officer, there is electric and manual stabilizer trim and manual aileron and rudder trim.

Various switches and indicators are located in the forward, overhead and Flight Engineer's Panels. One of them is the Flight Controls Electronic Systems (FESC) Panel located on the overhead. It contains controls for:

ACS (not on all aircraft)
Yaw Stability Augmentation system (YAW SAS)
Stall Warning Computer (STALL WARN)
Pitch Trim Computer (PITCH TRIM)
Direct Lift Control and Auto Spoiler Computer (DLC/AUTO SPLR)
Automatic Throttle Systems (ATS)
Mach Trim (MACH TRIM)

Each of the systems has two channels, hence there are two switches for each system.