Avionics Bending: APFDS Engage Panel - Part 1

L-1011 APFDS Engage Panel

The next component of the Lockheed L-1011 Autoflight system is the APFDS Engage panel. This panel is located in the middle of the L-1011 Glare Shield (see below)

The panel has switches for the Autopilot A and B as well as the Left and Right Flight Director (FD). The Autopilot of the L-1011 as both a Control Wheel Steering (CSW) modes as well as a full Command (CMD) mode. Both the A and the B system of the auto flight systems work independent unless the aircraft is in Approach/Land (A/L) mode during which both automatic flight systems are required. 

The panel that I am using for this demo and the test integration with X-Plane is one of several APFDS Engage panels we have at the museum. This particular panel is a little beaten up, but, it makes for a great test instrument. The switches on the panel have long extensions and are frequently called "bat-switches". The flight director switches are normal toggle switches with the SYNC position having a spring return. The autopilot swathes are magnetic latch switches that will be held in certain positions by solenoids. For example, if the the autopilot system is not ready, the switches can not be moved out of the OFF position, or, if engaged and the pilot presses the A/P Disengage switch on the control wheel ... the bat switches will return to the OFF position. Below is a short video showing the action of the switches as well as a schematic of the panel taken from the WDM fiche.

APFDS Engage Schematic - From L-1011 WDM