> The pilot had set the trim so that the aircraft would lift off from the step and begin to climb away. The rudder trim was set almost as far right as it could go. The pilot described the take-off as quick and easy. “I let it lift off by itself. It was well-trimmed and it lifted off normally by itself.”
Further down.
> The maintenance team discovered an incorrect right wing geometric twist, which was unrelated to the hangar roof collapse but probably happened during repairs done previously in the USA. As a result, the aircraft had a tendency to roll and had been uncomfortable to fly because of a lack of aileron trim. This might explain why the pilot had the aircraft trimmed full right rudder on take-off: to correct for this roll.
He may have actually had too much rudder. They don’t say this explicitly, but correcting for roll with rudder means you’ll be cross controlled.
He was dangerously near stall speed without realizing it. Some turbulence could cause a small partial stall.
If the airplane was straight, it would have just dropped the nose a bit and corrected. But with a twist in one wing and 2/3 of rudder trim engaged, it’s more like it entered a snap roll. One wing was stalled, one was still making lift.
The airplane felt fine to the pilot, but it was essentially modified to be a snap roll machine. I don’t think a stock 185 would have even been capable of what happened here.
Kind of my point though. The pilot was disengaged from the controls, and relying on trim settings for takeoff. Regardless of the different roll characteristics, if he had been actively controlling the yoke at the time rather than needing a split second to react and correct, the accident probably would not have occurred.
Note that the twist had been repaired before the accident.
> When they repaired the damage to the right wing, they also corrected the geometric twist, removing the aircraft’s tendency to roll.
However, since the repairs were completed five days before the accident, the pilot may have set the rudder based on pre-repair experience with the plane. He may not have been informed of the change in twist, or may not have understood it.
Further down.
> The maintenance team discovered an incorrect right wing geometric twist, which was unrelated to the hangar roof collapse but probably happened during repairs done previously in the USA. As a result, the aircraft had a tendency to roll and had been uncomfortable to fly because of a lack of aileron trim. This might explain why the pilot had the aircraft trimmed full right rudder on take-off: to correct for this roll.
He may have actually had too much rudder. They don’t say this explicitly, but correcting for roll with rudder means you’ll be cross controlled.
He was dangerously near stall speed without realizing it. Some turbulence could cause a small partial stall.
If the airplane was straight, it would have just dropped the nose a bit and corrected. But with a twist in one wing and 2/3 of rudder trim engaged, it’s more like it entered a snap roll. One wing was stalled, one was still making lift.
The airplane felt fine to the pilot, but it was essentially modified to be a snap roll machine. I don’t think a stock 185 would have even been capable of what happened here.