Tuesday, 5 November 2013

Mk10b autopilot

An annoying snag was sorted out on Sunday when Rick and I decided to nail a problem with the autopilot which had not engaged for some time.

Powered up & ready!
The autopilot powered up and indicated it was ready for use but would not engage and I decided to replace the 3 main control boxes located behind the co-pilots seat and to the right of the 6th (crew chief seat).

These boxes are the Servo Control Unit, Platform Control Unit and Locking unit. The latter two boxes are a 'doddle' to swap, the first one however entailed removing the 6th seat, in order to remove it. However, this was achieved okay and all power supplies and fuses checked out and no problems were found and a power-up tried.

Frustratingly, the autopilot did not engage!  So, wounded we retired to consult the books and I replaced all 3 original boxes.

3 Auto piilot control boxes
Rick, after studying the diagrams suggested the pilot or co-pilots autopilot disconnect thumb buttons may be the culprit and dived down into the bomb aimers compartment to locate the associated terminal block. These were found and continuity check through the co-pilots button proved it was working. The same could not be said for the captain's and it showed no circuit. In effect it was in permanent 'trip' selection.

Rick isolated the two wires to the switch and put in a link to simulate the switch and BINGO the autopilot engaged!

Auto pilot engaged rudder channel selected
Auto pilot engaged
Auto pilot disengaged

We tried it in all functions in roll, pitch and yaw and it functioned as advertised and yes, we were rather pleased with ourselves, we've just got to sort out the switch or find a replacement.
Roll to port
Roll to starboard

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