L-1011 Trainer Installation: Airspeed and ADI Power-UP

L-1011 Trainer - A/S and ADI Power-Up

Both the Airspeed Indicator and the ADI are Synchro driven instruments. So simply supplying power to them doesn't really do all that much, however, it's all part of the power-up process. In the video below you can see that the Airspeed indicator does not quite know how to display a Mach number since we are not feeding speed and altitude data to it quite yet, and the ADI clears the R/O flag and the GATE flag. As we start producing valid signals with the compute all the flags will clear and the instruments will start displaying simulator data.

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

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)

• 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: SFENA Attitude Director Indicator (ADI) (Analysis)

Today's posting is on a set of beautiful Attitude Director Indicators. The ones that I selected for the project are actually not common on the L-1011, but they flew on an Airbus A300. Which from a time period point of view, overlaps with the L-1011. The devices are made by SFENA, France and the part number is N32aAM with an original manufacturing date of January 1982.


The ADI as indicators for:

• Aircraft Attitude
• Bank Angle
• Turn Coordination
• Glide Slope Deviation
• Localizer Deviation
• Fast/Slow on Approach
• Flight Director Pitch
• Flight Director Roll
• Decision Height
• Attention

To see the ADI in check this blog posting: SFENA ADI Working with XPlane

The next few pictures show the unit without the back cover. The instrument is really beautifully engineered. Just as with many other SFENA devices, the entire instrument is built very modular. The ball representing the gyro has two motors: (a) one for pitch inside the globe and (b) another for roll on the backside of the C-shaped mount.





Both the roll and the pitch motors are supported by a 400Hz resolver.




The two flight director bars in action.

1) Flight Director directs a turn to the left.



2) Flight Director directs a climbing right turn.