This is an air france bulleting destinated to the air france 777 crew, posted on Rcoco forum.
this is my traduction, so sorry for the mistakes.
On takeoff from lagos, during the night between 11th and 12th of january, the F-QSQI [ndlr : it must be the F-GSQI] crew initiated a high speed RTO, and the airplane came 900m from the runway 36L threshold.
On VR, the captain who was Pilot Flying felt a heavy strength on the controls, and thought about the stabilizer jam. He estimated the aircraft was unsafe to fly.
He aborted the takeoff, maximum speed reached was 161 kt, and deceleration was -0,48g.
After self taxiing back to the stand escorted by security, 6 tires deflated, brakes were cooled down by firefighters. An information communicated to crew and passengers enabled a disembarkation by door 1R.
The crew, once at base, was welcomed by the division.
All the brakes and tires have been changed, a fuse and boogies inspection is in progress.
The ASR reveal the following facts :
After pushing the TOGA buttons, the engine EPR didn’t increase.
The captain manually set the takeoff power and observe the A/T is not engaged. Deciding to arm it, he engages too by inadvertance the autopilot. None of the both pilots notice it during the takeoff roll.
Boeing recorded 7 AP ground engagement cases on B777 on similar conditions.
What are our protections ?
If the setting thrust sequence is not conform ather the N1 stabilisation at 55 % and the TOGA push, we have two options :
- rejecting takeoff
- continuing takeoff with AT unavailable, the thrust needing to be set manually by slowly pushing the throttles to takeoff thrust. Thrust adjustments by N1 indications must be done before 100 kts. In this case, THR REF does not appears on FMA.
Also, a slight forward pressure on the yoke increase the nosewheel efficiency for lateral control until 80 kts.
During crosswind, wings must be maintained horizontal by using the ailerons control (yoke in the wind) as necessarly.
Those two actions on yoke allow to identify a possibly control jam during takeoff roll.
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