Avionics Bending: L-1011 Autopilot - Pitch Mode and Heading Panel - Part 3

L-1011 Autopilot - Vertical Speed Select

The VERT SPEED window and Vertical Speed Select thumb wheel are two pretty interesting components of the Heading/Pitch Mode Panel oft he Lockheed L-1011 autopilot. The Vertical Speed is indicated using a tape that is motorized and the thumbwheel allows adjustment of the value once the VERTICAL SPEED (VS) mode is selected on the panel.

The module takes +12 and -12V bipolar power. For todays hack I have worked on reading the vertical speed select values as output by the panel. The values are between -5V for 4000 feet per minute climb and -10V for 8000 feet per minute descent. I love the face that 8000 fpm can actually be selected on the L-1011 autopilot ... makes sense for an emergency descent ... of course, would probably also make about 80% of the 280+ people behind you loose their lunch. :)

Here is short video of the values produce by the panel ... for detail information please also see the chart below:

Avionics Bending: L-1011 Autopilot - Pitch Mode and Heading Panel - Part 2

Over the holidays I have been working on the digital input/output integration of the L-1011 panels using the Interbus components that I chose a few months ago. The project is not going quite as fast as I had hope it to progress due to chronic funding problems. However, every week I am making are small steps towards breathing live back into this great machine. After all, it is the largest project I have ever undertaken.

Here is a test setup for the Ethernet to Interbus I/O testing. The test setup consists of a single 32 port Digital Input and one 32 port Digital Output element. The Interbus terminal, DI-32 and DO-32 modules are made by Phoenix Contact.

Phoenix Contact Interbus Test Setup

Slowly the autopilot is becoming clearer to me and how to interface it with X-Plane. Below is a short video that demonstrates the initial digital integration between the Heading/Pitch Panel mode selectors and X-Plane.

Avionics Bending: L-1011 Autopilot - Pitch Mode and Heading Panel

The Avionic Flight Control System (AFCS) on the L-1011 is controlled via a number of panels located on the L-1011 glare shield. Most commonly these panels are referred to as the "autopilot" control panel. The autopilot on the L-1011 is a digital system that had analog inputs ... as you can see in the image above and the images following below. The later L-1011-500s had a digital AFCS panel also located on the glare shield. The digital version of the AFCS panel is not easy to find and there was one on eBay a few weeks ago and someone snatched it right from under my nose ... i am still sore about that one.

Anyway, in this posting I show you the status of my work with one of the panels ... the Heading/Pitch Mode Panel. The panel is located on the left hand side of the autopilot panel assembly and came in two version; one version that is like the one shown above and another that combined the Thrust and the Heading/Pitch Mode panel together (as seen below).

The right hand side of the panel has an engage button for heading control ("HDG") as well as a turn knob and a display for the selected heading. This side of the panel directly controls the L-1011's Roll Computer. In the image below the Roll Computer is engaged and the heading is set to 93º.

The left hand side of the same panel has the inputs for the aircraft's Pitch Mode. The L-1011 can pitch for 4 different modes:

• Vertical Speed (VS)
• Altitude 
• Indicated Airspeed 
• Mach Speed

The image below shows the Vertical Speed mode set on the L-1011's Pitch Computer and a target vertical speed for 1500 feet per minute climb.

There Vertical Speed controls on the panel are quite interesting. But more about them when I show you the schematic for the instrument later on. The ALT mode, when engaged holds the aircraft altitude at the moment of engaging the autopilot. The pitch for Indicated Airspeed and Mach is pretty self explanatory.

In the image below we would be holding the current altitude with the autopilot as well as the aircraft's heading. In other words, both the L-1011's Pitch and Roll Computers are engaged and, when the AFCS system is set to CMD will control the aircraft pitch and roll axis.

So now a few words about the VERT SPEED windows and the DN/UP switch. Prior to engagement of the VS mode, the tape in the the VERT SPEED window shows the aircrafts vertical speed. So in other words, unless "VS" is lit up, the VERT SPEED window will show the same indication as the vertical speed indicator. Once the VS mode is engaged the motor for the tape disengages and vertical speed adjustments can be made with the thumbwheel.

I have not gotten that tape motor part to work yet, however, it shouldn't be too hard to do. Below is the schematic for the VERT SPEED and DN/UP thumbwheel:

And a more enlarged view of the same schematic showing the ADC and Pitch Computer schematics as well:

L-1011 Procedure: Pre-Flight Check - Flight Recorder, Waste Water, Oxygen, Doors

From Eastern Flight Training Manual

Flight Recorder

• Set day, month, flight number, weight, pilot number and leg; then insert the data on the flight recorder by pressing DDI insert button 

Rated EPR Mode Panel

• Set the current runway temperature with the thumbwheel and press TO-1 or TO-2
• Compare this data to the computed data to verify the integrity of the TAT/EPR computer, which may then be used for climb, cruise and go-around.

Humidity Control

• The humidity control is used, as necessary, to remove moisture from the air. Normally ON, except in cold or very dry climates. 

Oxygen Panel

• Confirm the green OXYGEN FLOW light is extinguished and the deployment switch is guarded and safetied. 

Annunciator Panel 

• Check for abnormal indication.

L-1011 Trainer Installation: Circuit Breaker Cabling

L-1011 Trainer Installation - Circuit Breakers

It's been a busy weekend for installing things into the simulator. However, there is not much to visually show because 90% of what I have been working on has to do with the hundreds of circuit breakers in the Lockheed L-1011 cockpit. As discussed a while ago, the L-1011 has 3 circuit panel groups.

• CB1 - is located right behind he pilot's overhead panel. 
• CB2 - is located above the flight engineer station 
• CB3 - is located to the right of the flight engineer station

Circuit Breaker Panel #1

From: TWA L-1011 Reference Manual

Circuit Breaker Panel #2

From: TWA L-1011 Reference Manual

Circuit Breaker Panel #3

From: TWA L-1011 Reference Manual

From: TWA L-1011 Reference Manual

Every instrument and every component in the L-1011 simulator runs through the correct circuit breaker on the respective panel. This we we are keeping with the desire of creating maximum realism and also with keeping the machine as safe to operate as possible.

L-1011 Trainer Installation: Telex Airman 750 Headsets

Telex Airman 750 Headset

No serious cockpit project can go without authentic headsets. The Telex Airman 750 headset has been a standard item in commercial cockpits for a very long time. The Airman 750 is sound optimized for

radio communication and it has 400Hz hum reduction built right into the headset.

So, to add to the realism of our Lockheed L-1011 cockpit we received a donation of three Airman 750 headsets. The headsets had been heavily used before and most of the foam had done what most old foam does ... it had fallen apart. However, since the Airman 750 is still a headset that is going very strong ... finding the replacement parts was no problem at all. I can't wait to get them into the cockpit and connected to our audio panels.

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L-1011 Procedure: Preflight Check - Engine Status Panel, Clock and APU

From Lockheed L-1011 

Engine Status Panel

• Airborne Vibration Monitor: With the selector switch in NORM, test the vibration monitor by first latching in the FAN switch and pressing the Test Switch. Then unlatch the FAN switch latch in the TURB switch. This checks Airborne Vibration Monitor (AVM) system and indicators. Indicator pointers should drive to approximately 4 Units. The vibration caution lights (in each indicator) should illuminate at 2 1/2 units, and the ENG/APU STATUS annunciator on the master caution/warning panel should illuminate. Unlatch TURB switch. 
• Check N2 indicators show zero and the overspeed indicators are at 100%.
• Reverser pressure lights should be extinguished. 

Clock

• Set the clock to the correct time.

APU

• Check APU for normal operation. NG and TGT indicators are in the green band when the APU is running. 

L-1011 Procedure: Preflight Check - Fuel System, Fuel Control Amplifier, Fuel Used and Engine Oil Panel

From Lockheed L-1011 Flight Training Manual

Fuel Panel

• Verify refueling is complete and the REFUEL POWER ON switch legend is extinguished. 
• Test the fuel quantity system. Check that fuel quantity indicators and digital readouts drive towards FULL. The 2L and 2R INBD LOW quantity lights illuminate, and FUEL SYSTEM annunciator light on the CAWP is illuminated. 
• Latch in one pump switch on 2L or 2R thank, and open all three cross feed valve. This provides full pressure to all engines in preparation for start. 
• All amber lights should be extinguished, and all tank valve and cross feed valve switchlight flow bars illuminated, as well as one tank pump switch flow bar in 2L or 2R tank. 

Fuel Dump Panel 

• All light are extinguished.

Fuel Control Amplifier

• Switches should be unlatched and guarded and OVRD legend extinguished. 

Engine Fuel Used Panel

• Turn the test knob on each indicator and observe the fuel flow indicators drive to 10,000 pph, and the Fuel Used indicators increase at that rate. Fuel Used indicators are then reset by the Fuel Used Reset switch on the Fuel System panel. 

Engine Oil Panel

• Check all FILER PRESSURE lights extinguished. 
• Test the pressure gauges with the PRESS IND test switch. Oil pressure indicators go to the 9 o'clock position. 
• The (3) three oil temperature gauges should indicate approximately the same, depending on time since engine shutdown. 
• Oil quantity should be adequate for the flight (normally 15 - 20 US quarts)

L-1011 Trainer Installation: Interbus Installation into S/O Station

L-1011 Trainer - Interbus Installation

The Lockheed L-1011 cockpit has literally hundreds of switch positions and an even larger number of annunciator lights. For the computers receiving switch data and driving the annunciator lights we use Interbus components. Interbus is a relatively old bus format but is perfect for the use on the simulator since this is a field bus system that readily works in the 24VDC domain. In a few previous postings we talked about installing Interbus Terminal stations in the Flight Engineer's (SO Station), the Overhead and the Main Instrument Panel. All the Interbus components we selected for the simulator mount onto DIN rails and will be fully field replaceable.

In order to get the DIN rails added to the simulator we are blessed to have the master of all hardware mounting, Mr. Jim Blassco, create custom mounts for the simulator. 

First we had to find a good position in the simulator's Flight Engineer station to mount the devices. We picked a spot towards the top of the station for two reasons: a) there was really a lot of space there and b) we would get good airflow over the components for cooling. 

L-1011 Flight Engineer Station - Digital I/O Bracket

Then the fun started, Jim made some custom designed brackets and introduced me to the use of an angle drill ... an amazing piece of hardware that looks like a gigantic dentist tool.

Jim Manufacturing Brackets for the L-1011 Trainer

With the brackets in place we installed the steel DIN rail (they flex a lot less than aluminum rails) and mounted the Interbus modules right onto it.

L-1011 Trainer - Digital I/O Bracket

L-1011 Trainer - Digital I/O Buildout

Every day is a step towards the finishing of this project. However, as Kevin pointed out ... in sim building a lot of the fun is actually in the journey of putting such a complex machine together. Thanks to everyone for their awesome support!

L-1011 Trainer Installation: Glare Shield Replacement

L-1011 Trainer - Glare Shield - Autopilot

The L-1011 trainer that we got from Delta did not come with any real instrumentation. All of the instruments you have been seeing as part of the blog postings are instruments we replaced with real flight hardware used on actual L-1011s. Today, we replaced the last photo mock up on the simulator ... the glare shield autopilot and radio components. In the image below you can see the image that was pasted onto a plate and mounted in place of the autopilot under the glare shield. This has now been replaced with a custom made plate and with the actual control components:

Before

L-1011 Trainer - Original Autopilot Photo Replica

After

The glare shield is not only home to the autopilot components, but also holds the VHF NAV 1 and VHF NAV 2 radio as well as the RADIO/NAV selector for the HSIs, a ENGINE 2 warning light and a FIRE warning light.

L-1011 Glare Shield

L-1011 Procedure: Preflight Check - Hydraulic and Electrical Panel

From Lockheed L-1011 Flight Training Manual

Hydraulic Panel 

• Hydraulic Fluid level - minimum 3/4 full. 
• The suction shutoff flow bars illuminated and the engine driven PUMP S/O flow bars illuminated. 
• The only amber lights that should be illuminated are the four engine driven PUMP OUTPUT LO PR lights. 
• Start B3 and C3 electric pumps and PTU's to charge the hydraulic pump accumulators. After that, place the pumps back to off. 

Electrical Panel

• If external power is available, it should be used. If not, use the APU
• IDG temp and power meter should reflect ambient or residual temperature and zero load. 
• With APU power, the only flow bars illuminated will be the APU generator field and generator breaker, and the three (3) bus tie breakers. 
• The only amber lights illuminated will be the three (3) engine driven IDG Disconnect LOW PRESS switches and the Open lights for each generator field and breaker. All other lights will be extinguished. 
• The Essential Power source selector should be in the NORM B3-(G1) position. 
• The Battery Switch is to ON 
• With the DC Meter selector, check all DC sources. Indications will be bus voltage and respective T/R amperage. All amperages should be equal. Battery should be pulse charging. Return selector to the essential transformer rectifier (ESS) position after checks. 
• Place the AC selector to the engine to be started. 

L-1011 Trainer Installation: Switch (Digital) Input Modules

Interbus Input Module Preparation

Cables, Cables and more Cables. The next few weeks are going to be filled with lots of postings on the digital cabling process of the L-1011 Trainer at the museum. The digital cabling connects all of the hundreds of trainer switches and lights to the computers. Today, I started building out the first of many digital input modules for the simulator. As described in a few earlier postings, I will be using a PLC system based on Interbus for the switch input and for the annunciator and switch light output on the L-1011 trainer.

interbus 8-bit Switch Input

Each of the digital input (DI) modules has 32 inputs that are arranged in 8 channels + 1 GND signal per group. The image above shows the 8 digital input lines that will be coming from switches. Each cable represents a bit and together each connector represents one Byte of information on the Interbus. 

L-1011 Procedure: APU and Air Conditioning Startup

When the simulator is powered up and the EXT POWER switch located on the simulator power control panel is in the ON position the simulator emulates the behavior of the aircraft sitting on the ground with external power connected to it.

The next step will be to start the APU. The APU will be started by the Flight Engineer with the following procedure:

If external power is not in use, but the green AVAIL light is illuminated, actuate the external power switch. This will provide AC and DC power to the simulator systems.

Note: If external power does not turned on in the simulator, turn the battery switch ON . This will provide power to the simulated Ground Control Unit (GCU) and the DC standby bus. Once external power is on the simulator, it will be able to power the GCU through the DC standby bus.

Prior to starting the APU, check the fire detection system for the APU and engines.

1.  Detector loop selectors ....... BOTH

2.  Detector loop lights .. EXTINGUISHED

3.  Press A & B Test buttons simultaneously and check:

• Waring bell is on (press cutout to silence)
• A and B loop lights illuminated 
• Master fire warning lights on glare shield illuminated 
• Fire Pull handles illuminated 
• FIRE DET LOOP annunciator light on Caution and Warning Panel

APU START PROCEDURE

From Lockheed L-1011 Flight Training Manual

1. Select DC meter to BAT and AC meter to APU. Check that the BATTERY CONDITION light on the APU panel is not illuminated.

2. Position the APU master power switch to ON. (OBSERVE: Primary emergency shutoff fuel valve opens. AUTO FIRE SHUTDOWN ARMED light on APU panel illuminates.

3. IF external AC power is available, turn on #2 fuel tank pump.

4. Position the Bleed Air Mode switch on the APU Panel to MIN MODE.

5. APU Bleed Air S/O switch unlatched and OPEN light extinguishes.

6. Press the Start switch until the DOORS IN TRANSIT light illuminates. (OBSERVE: DOORS IN TRANSIT light cycle as the engine inlet and APU compartment ejector doors open).

After pressing Start, monitor the following:

• DONT LOAD light and APU GEN OIL PRESS light (on the electrical panel) illuminated after DOORS IN TRANSIT light extinguished. 
• While the APU RPM and APU TGT are increasing, check the Battery volts and amps. If either is low the simulator is presenting you with an abnormal APU start. 
• When APU RPM and APU TGT have stabilized in the green range, with the DONT LOAD light extinguished, check that the APU generator field flow bar is illuminated, generator oil PRESS light extinguished, and generator volts and frequency are normal 

      Voltage = 117 +/-2, Frequency = 401 +/-2Hz

• Check APU generator KW load. 81KW max, but normal around 40-50KW with system on.
• DC ammeter indicates normal battery charging. 

Preparing for APU Air

From Lockheed L-1011 Flight Training Manual

1. Aft fuselage ISLN and both crossbreed valves are latched in.

2. Pack Flow Control valve switches unlatched (closed). When Pack Flow Control valve switches 2 and 3 are unlatched, their hot air valves should be unlatched at the same time. 

3. Pack Auto/MNL switches latched in --> AUTO illuminated 

4. Ground control switch latched in and legend not illuminated. 

5. Aircraft zone air trim switches latched in and not illuminated. 

6. Zone temperature control to 12 o'clock position. 

Accepting APU Bleed Air

From Lockheed L-1011 Flight Training Manual

1. Latch in APU Bleed Air S/O switch and observe the OPEN legend illumination.

2. Observe bleed air pressure on the engine duct pressure indicators.

3. Latch int he No. 2 pack flow control valve and its hot wire valves.

4. Turn the APU Mode Selector to Normal.

Avionics Bending: Making Cables for the Simulator

Finished Deutsch Connector with Strain Relieve

Since a lot of time the last few weeks has gone into making cables for the instruments and panels of the L-1011 trainer at the museum I thought it would be fun to show you how I make these cables. By the way, there are pretty strict standards on how to makes cables used on actual aircraft and the cables that I make somewhat loosely follow them, however, you should not consider this a guid on how to make cables used on actual aircraft.

Many of the connectors that we use on the simulator came out of actual airplanes. Every now and then you can get a friendly scrapper to cut off the cable ends for you right before the aircraft is scrapped. This is how we ended up with many connectors looking like this:

Tools 

Here are the tools that I use for making cables.

To get the old cables and pins out of the connectors you will need an extraction tool. Extraction tools come in all forms and shapes and are somewhat specific to the connector manufacturer. On circular avionics connectors the most common pin size is RED. The extraction tool below is metal and little more durable, but there are also plastic tools that only cost a few cents and do the job well .... if you are not planning on doing hundreds or pins. By the way, Clay Young from Precession Electronics here in Atlanta showed me a cool trick; when you dip the extraction tool into alcohol prior to using it it will grip to the pin better.

Insertion/Extraction Tool 

Jim just recently found a lot of tools for the museum and they have been a huge help. To put pins back onto the ends of your cables you will need some sort of a crimp tool that can be used with the pins used on circular connectors. Again, there are different crimp tools for different manufacturers. The most common crimp tool is show below and is made by Daniels Corporation and is called the M22520/1-01. The tool that we have at the museum has a turret head on it that can crimp three different sizes (green, red and blue)

Daniels Crimp Tool M22520/1-01 with Turret Head

The pin is inserted on the other side of the turret and then crimped by applying lots and lots of ponds via an easy to operate ratcheting grip.

SETP 1: Pull out the unused pins with the extraction tool.

Keep the pins! They will come in handy when you are making cables. By the way, when these connectors are being built for use on actual aircraft, all pin positions are filled with pins ... regardless of having a cable attached to it or not. These "unused" pins can be re-used in the simulator which then cuts down on the cost. 

STEP 2: Make the cable

Using the Crimp tool, I am now crimping one of the spare pins onto the AWG 22 cable and insert it into the correct location in the connector

STEP 3: Strain and Vibration Relieve of the Cable

If you don't strain relieve the cables on the backside of the connector you risk that, over time, the cable inside of the connector might break off from the pin. This can happen quite easily if you have a lot of strain on the cable, or, if the weight of a cable bundle pulls on a single cable in the connector. Therefore, always build a strain relieve for the cable. 

I use the back-shell clamps that fit the Deutsch and Amphenol connectors to do so. In order for the back-shell not to clamp down on the actual wires, or, as is the case with most connectors, the cable bundle is too small for the clamp to secure the cables I use 3M Temflex Rubber Splicing tape. 

Temflex tape is a thick rubber tape that is not adhesive. It is perfect to wrap around the cables and build a plug with allow the back-shell clamp can clamp down on.

Once in place, the Temflex tape absorbs all strain and vibration that the cables might exert on the pins. 

And this is how I make cables :)