PPRuNe Forums - View Single Post - Air France B777 control issues landing CDG
Old 28th Apr 2022, 02:53
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BuzzBox
 
Join Date: Mar 2002
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Originally Posted by tdracer
If they activated the breakout (surprising - the normal loads on the 777 control wheels are pretty light as long as you're not doing something stupid like pulling into a stall - to have to apply greater than 50 lbs. on the wheel should have been a dead giveaway that the pilots were working against each other), I'm reasonably sure it takes a maintenance action to reconnect them (I'm thinking it's a frangible link but I'm not sure about that). So that would explain the aircraft being grounded for a few days after the event.
The control column breakout mechanism is a cam and roller mechanism, held together by springs. The flight parameters in the report show the control columns were ‘desynchronised’ for about 15 seconds. After that, they again moved in unison. The control wheel jam breakout mechanism has two force limiters and two lost motion devices that allow the other control wheel to continue roll control if one of the control wheels jams. The flight parameters show the control wheels were desynchronised for two brief periods of 2 seconds and 5 seconds duration during the same period the control columns were desynchronised.

The force required to override either breakout mechanism is 50 lb.

Last edited by BuzzBox; 28th Apr 2022 at 12:14. Reason: Updated with details of the control column and control wheel breakout mechanisms.
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