Original Flight Hardware: Fuel System

The fuel control on the Lockheed L-1011 take a prominent spot on the lower section of the flight engineer panel. There are several tank configurations for the -1, -200 and -500 models of the L-1011. The configuration that I have a tank panel for is shown below.


Here is a general description of the L-1011 fuel system as described in a 1977 Eastern Airlines flight manual:

The fuel system consists of four wing tanks which operate as a three-tank system. The inboard tanks (No. 1 and No. 3) supply ENG1 and ENG3. The outboard tanks (No. 2L and No. 2R) are manifolded together through a flow equalizer to supply ENG2 with fuel. Tanks 2L and 2R are divided into inboard compartment and outboard compartments. The compartments are connected by a fuel line equipped with a float valve. Fuel is used first from the inboard compartment until 1000 pounds remain. Fuel from the outboard compartment then transfers through the float valve to maintain the 1000 pound level in the inboard compartment until the outboard compartment is depleted.

The No. 2 engine fuel lines supply the APU. When the ENG2 tank valve is closed, the APU can be supplied from tank No. 3.

The picture below shows the panel as I have it today (12/31/2009). There are 3 tank gauges missing (the one on the left hand side is actually a tank gauge from the external fuel control panel of the L-1011).


Each tank has two fuel pumps and fuel flow can be controlled with cross-feed valves (see below). An in-transit light for each fuel valve is illuminated, while the valve motor is engergized, during valve operating or closing.

Tanks 2L and 2R normally act as one tank. Fuel from tanks 2L and 2R feeds through the flow equalizer even during crossfeeding.


The fuel temperature in each tank can be displayed with the FUEL TEMPERATURE INDICATOR and the FUEL TEMPERATURE TEST SWITCH located on the lower left of the Fuel System panel.






Panel Location

Original Flight Hardware: Humidity Control

To minimize Environmental Control Systems (ECS) condensation in the cabin of the Lockheed L-1011, the ACM discharge temperature is maintained at 38F (2C) regardless of any other demand inputs. The system is to be used whenever the aircraft is on the ground and ambient temperature is above 50F and should not be used above 15,000 feet.



Panel Location

Original Flight Hardware: Wiper (Left Side)

The Lockheed L-1011 has windshield wiper controls for both the captains forward facing window and for the first officer. Some L-1011 configuration have both wiper controls side by side right above the F/O. But, the more traditional layout is for the control to be on the each side of the overhead panel. The WIPER panel on the capt. side of the overhead panel has more control elements as compared to the one on the F/O side.



Here is the explanation of the Windshield Washer System:

The windshield washer system sprays washer fluid on the windshield wipers to clean the windshield. A single switch on the Captain's windshield wiper panel controls spraying of washer fluid on both left and right windshield panels.

A combination reservoir/pump is located in the forward electronic service center. A bayonet type cap is used to refill the system. Fluid is routed from the reservoir pump to four spray nozzles, two nozzles for the left windshield and two for the right windshield. Two control valves, one located in the left side console and one located in the right side console, provide selective fluid flow to the windshields.



Panel Location

Cockpit Design Study: Windows

The Lockheed L-1011 has awesome cockpit windows. The panoramic few fore the pilots is outstanding and the individual panes are larger and more accentuated than on comparable aircraft from the same time period. I would say, that the cockpit glass used on the L-1011 was way ahead of it's time.


The cockpit windows on the L-1011 consist of 6 panes. Each acrylic glass pane has it's own de-icing system embedded into the laminate, but on most aircraft the #2L and the #2R window head was disabled. The elevated observer seat is right next to the #2L windows and gives the observer an awesome view out the cockpit.





Each window pane has a unique shape and consists of laminated acrylic glass panes with a gas filled insulator layer between the outer and inner glass panes. The largest single panes are the forward facing panes for the captain and the first officer.




The glass panes are uniquely shaped and of varying thickness to provide zero distortion, even on the forward facing panes that have a significant curvature to them.

Original Flight Hardware: Cabin Pressure Control (Sub-Panel)

After a few days of rest (I took a brief vacation), I am continuing my blog postings with the last and final panel of the 4 sub-panels of the pneumatics panel of the Lockheed L-1011. The pressurization system of the Lockheed L-1011 is electronically controlled. Generally, pressurization is controlled by the control of cabin exhaust.

Cabin pressure is controlled by a selective, automatic system with manual override control. Major components include the cabin pressure control panel (discussed here), the cabin pressure controller, and two electrically operated cabin outflow valves.

Pressurization control is normally operated in the automatic mode. In this mode, the flight crew selects the desired cabin or aircraft altitude prior to takeoff, and sets barometric correction and landing filed altitude prior to descent. The pressurization system is fast responding and pressure transients are controlled below normal threshold of detection. In the automatic mode, cabin altitude is controlled at a fixed rate of change until the selected altitude is reached. For increasing altitude, the rate is 500 feet per minute; and for decreasing altitude, it is 300 feet per minute. Other fixed rates of change may be selected by the flight crew with complete automatic operation. The selectable range for increasing altitude is 200 to 1500 feet per minute and for decreasing altitude the range is 120 to 900 feet per minute. The selectable rang for cabin altitude is from 1000 feet below sea level to 10,000 feet above sea level.

The controller automatically controls the outflow valves to limit cabin pressure differential to a nominal 8.44 PSI. This provides a cabin altitude of 8000 feet at an aircraft altitude of 42,000 feet. A sea level cabin altitude can be maintained up to an aircraft altitude of 22,000 feet without exceeding the maximum pressure differential.

In the top left corner are indicators for the safety relief system of the L-1011 pressurization system. The two annunciators are "SAFETY VALVE FWD" and "SAFETY VALVE AFT". If OPEN is illuminated, the respective pressure safety relief valve is open. The CABIN ALTITUDE HORN CUTOUT SWITCH is a momentary push button which silences the warning horn when cabin altitude reaches 10,000 feet.


Right below the safety relief system indicators are 3 instruments (one is missing in my current collection). The three instruments are:

• Cabin Differential Pressure
• Cabin Rate of Climb Indicator
• Cabin Altimeter (missing from the picture)

In the image above I have highlighted the ALTITUDE SELECT INDICATOR AND KNOB. The ALT SET knob sets selected cabin flight altitudes. FLT shows present aircraft altitude. CAB shows cabin altitude when pressurized to maximum differential. The BAROMETRIC CORRECTION INDICATOR AND KNOB is used to set the barometric pressure and program pressurization controller.

In the image above we can see the three main system selector knobs. From the left to the right they are:

• MODE SELECT SWITCH ... GRD CHK - permits normal system check on the ground. NORM - selects fully automatic pressurization at rates selected by normal rate knob, provided manual switches are not illuminated. On the ground the outflow valves are fully open. STBY - selects cabin altitude rates selected by standby rate knob without isobaric inputs to pressurization controller, provided manual switches are not illuminated.
• NORMAL RATE KNOB ... permits selection of automatic cabin altitude rate of change when mode select switch is in NORM. In detent, the cabin will ascent at 500 FPM and descent at 300 FPM. Rotation the knob out of detent increases or decreases cabin rate of change. Cabin altitude will level off at preselected cruise altitude.
• STANDBY RATE KNOB .. permits selection of manual cabin altitude rate cahgne when mode select switch is in STBY. HOLD - no cabin rate change, DSCD - increase cabin altitude rate of descent from 0 to 1000 FPM. ASCD - increases cabin altitude rate of ascent from 0 to 1000 FPM. The preselected altitude function is not operative.

The right hand side of the CABIN PRESSURE CONTROL panel is dedicated to manual operation. On top we have the AUTO FAULT LIGHT which, when illuminated indicates a problem with the automatic pressurization system in respect to out-flow or cabin altitude limits. The two outflow valve position indicators can be controlled with the toggle switches if the respective valve has been put into MANUAL mode (MNL will be illuminated).

Original Flight Hardware: Environmental Control System (ECS) (Sub-Panel)

The Environmental Control System (ECS) sub-panel is part of the large pneumatics panel located on the upper flight engineer station of the Lockheed L-1011. The panel is the measurement brains of the ECS. Here is a description of the various elements. Please note that today I don't have a Plack Flow Indicator (top left instrument).

Lets walk through the panel elements top left to bottom right:

• PACK FLOW INDICATOR ... indicators air output rate of selected pack (selected by the switch to the right of the pack flow indicator.
• PACK SELECT SWITCH ... selects the individual pack for flow and temperature indication.
• ECS TEMPERATURE INDICATOR ... indicates the temperature for position selected by pack selector switch (to the left) and ECS temperature selector switch (to the right).
• ECS TEMPERATURE SELECTOR SWITCH ... the temperature of each position is indicated on the ECS temperature indicator for the selected pack.
• COOL AIR OVERBOARD SWITCH ... controls overboard cooling air valves form galley and avionics compartments. IN - CLOSE is extinguished; opens galley overboard valve and arms both avionics compartment valves to open if flow is restricted. Both avionics valves open on the ground. OUT - CLOSE is illuminated and all three valves close.
• ECS MONITOR AVIONICS AIRFLOW INDICATORS ... OVBD is illuminated when respective cooling air overboard valve is open. LO FLO is illuminated when air in ventilation duct is too warm or flow is restricted (fans are operating).
• CARGO HEAT SWITCHES ... IN - recirculating fan motor is controlled by temperature sensing switch. COLD is illuminated when temperature is below minimum limit. When temperature exceeds maximum limit, HOT is illuminated and fan is turned off. OUT - recirculating fan is turned off and HOT is extinguished. COLD is illuminated if temperature is below minimum limit.
• CABIN AIR TEMPERATURE INDICATOR ... temperature of zone or duct for the position selected on cabin zone temperature selector (to the right) is indicated.
• CABIN ZONE TEMPERATURE SELECTOR ... temperature for selected zone or duct position is shown on cabin temperature indicator.
• ZONE/DUCT TEMPERATURE SELECTOR SWITCH ... IN - DUCT is illuminated. Temperature of selected zone discharge duct air is shown on cabin air temperature indicator. OUT - ZONE is illuminated. Temperature of selected zone is shown on cabin temperature indicator.

Original Flight Hardware: Cabin Temperature Control (Sub-Panel)

This posting covers the second of 4 sub-panels of the large pneumatics panel on the Lockheed L-1011. The panel is titled "CABIN TEMPERATURE CONTROL" and controls the hating and cooling of the vehicle interior (except for the cargo area).

The three air conditioning packs (as seen below) are located in unpressurized compartments on either side of the nose-wheel well. The packs utilize Air Cycle Machines (ACMs) that are operated by compressed bleed air.



Compressed air from the Pack Flow Control valve is partially cooled by the primary heat exchanger. This air is routed to the ACM compressor and, in the case of the #2 and the #3 packs, through a check valve to mix with hot air from the hot air distribution system. The partially cooled air may also pass through another check valve directly to the secondary heat exchanger when the air pressure is greater than ACM compressor discharge pressure.

The cooled air from the ACM turbine and from the Turbine By-Pass Valve are routed through a water separator tot he cold air plenum for distribution to the various zones. Ambient outside air is use for cooling the heat exchangers and is exhaust overboard through exit louvers for each pack. The louvers open and close automatically (during AUTO pack operation), or can be controlled manually (during MANUAL pack operation) to control pack discharge temperature.


Air for the cold air planum can also be supplied externally on the ground. The ground A/C connections feed directly into the #1 and #2 planum system.

The control elements for the PACK TEMPERATURE CONTROL are listed below:

• PACK FLOW CONTROL ... Controls pack flow control valve to schedule a constant mass air flow. Valve is energized closed and pressure opened. The illuminated flowbar indicates flow control valve is open. If OVHT is illuminated, the valve locks closed, flowbar is extinguished and associated hot air valve closes.
• TURB BYP INDICATOR ... Shows relative position of turbine bypass valve (TBV). Pointer moves to COOLER as TBV closes.
• PACK AUTO/MANUAL SWITCH .... If AUTO is illuminated. Ram air exit louvers and turbine bypass valves modulate automatically, to provide temperature control. Setting of zone temperature selectors control packs and zone trim valves to regulate the five zone temperatures. If MNL is illuminated. Arms COOL and WARM switches for manual control of ram air exit louvers and turbine bypass valve. The zone temp selectors control zone trim valves to regulate the five zone temperatures.
• HOT AIR VALVE SWITCH .. this switch opens and closes the control manifold for hot air to be mixed into the pack outflow.

Original Flight Hardware: Engine Bleed Control (Sub-Panel)

This posting focuses on a sub-panel of the Pneumatic System Control Panel of the Lockheed L-1011. The panel controls engine bleed air and is labeled as ENGINE BLEED CONTROL. The panel is organized into three bleed air systems. Each engine has a system as seen in the picture below. The individual engine bleed systems are issolated from each other by cross bleed valves, which are towards the edges of the red squares.


The bleed air system for the first engine, for example, has a number of isolation valves. These valves are:

• HI PRESS ... Isolation valve for hi-pressure bleed air for engine start
• ENG ISLN VALVE ... The engine isolation valve keeps system bleed air from the engine. Or in reverse, prevents engine bleed air from entering the bleed air system.
• CROSS BLEED ... Connects the bleed air system of the engine to the number 2 and even the number 3 bleed air system.
• PACK FLOW CONTROL ... enables engine bleed air to drive the corresponding air-conditioning pack.

Bleed air duct pressure is meassured on the bleed air system side of the engine issolation valve and shown in PSI on the associated instrument.

Besides driving the A/C packs, the engine bleed air is also used to (a) start other engines with and (b) to drive a number of de-icing systems. For example, in the picture below we can see that bleed air from ENG1 (or cross bleed air) can be sued for Left Wing Anti-Ice and that the bleed air form ENG3 (or cross bleed air) can be used for Right Wing Anit-Ice operation.


Bleed air coming from the Auxiliary Power Unit (APU) enters the system right between the engine isolation valve and the ENG2 bleed air isolation valve. The APU has the ability to drive the B and the C hydraulic systems via Air Turbine Motors (ATMs). The ATM controls are on the hydraulic panel, and we will look at that at a later point.

If neither bleed air from an engine nor the APU is available, compressed air can be supplied by a ground device. Ground air enters the system through the Engine 1 and Engine 3 as well as the cross bleed duct (as seen below).



The Engine Bleed Air system is monitored by a number of AREA and DUCT OVERHEAT sensors. Each system will sound a fire alarm in the cockpit and also illuminate a fire warning on the main instrument panel.



Engine bleed air, as mentioned above, enters the vehicle climate control system through the PAC FLOW CONTROL valves (see image below). In the next posting, we will take a close look at the air handles and the CABIN TEMP CONTROL panel.

Original Flight Hardware: Pneumatics Panels

The single largest panel on the flight engineering station of the Lockheed L-1011 is the panel that deals with bleed air, pressurization and vehicle climate control. You can see the actual location of the panel in the last image of this posting. The panel, however, is in fact a collection of 4 major systems, these systems are:

• ENGINE BLEED AIR CONTROL
• CABIN TEMPERATURE CONTROL
• CABIN PRESSURE CONTROL
• ESC MONITOR

I will discuss each of the sub-panels with you over the next four postings. Today, let me give you the highlights of the various systems:

BLEED AIR


The left hand side of the large panel is home to the Engine Bleed Control (top portion), the Pack Flow Control (middle section) and the Cabin Temperature Control (lower section)


CABIN TEMPERATURE CONTROL

The 3 systems fit together, because they are all driven by engine bleed air an the system logically flows from the top of the panel to the bottom of the panel. Engine bleed air drives the air conditioning packs which result in cabin heating (temperature control).

The right hand side of the large panel is home of the Cabin Pressure Control with pressure and warning instrumentation on top (the altimeter the goes into the large empty spot will come later) and the pressurization automation system below.

CABIN PRESSURE CONTROL


The bottom right section of the large panel is come to the Environmental Control System Monitor. Just like the power measurement section of the Electrical panel on the L-1011, the ECS C Monitor panel allows the second officer to monitor heating and air flow of the ECS system.

ENVIRONMENTAL CONTROL SYSTEM MONITOR




Panel Location

Cockpit Design Study: Center Console Dimensions

Dimension for the Lockheed L-1011 Center Console.

A: Width Across


B: Distance from Main Instrument Panel


C: Center Console Depth


D: Console Extension for Trim