The pilot reported that the CubCrafters CC11-160 was involved in an accident in 2020 before he bought it.
After purchasing the airplane he made extensive repairs to return it to an airworthy condition.
The accident flight was the first test flight since the previous accident.
The pilot taxied from his property to an adjacent off-airport soybean farm field near Findlay, Ohio, and performed a run-up without issue.
He then operated the electric horizontal stabilizer trim via the rocker switch on the control stick to the “nose up position” as indicated on the primary flight display (PFD). He then moved the trim back in a nose down direction towards the neutral takeoff position.
When the trim indicator reached the takeoff position, he removed his thumb from the trim switch and initiated the takeoff roll. The airplane accelerated normally, and he moved the control stick aft to rotate, however he felt a “very heavy” nose down pressure on the control stick.
He immediately aborted the takeoff and, in his effort to slow the airplane, it nosed over. The left wing and empennage sustained substantial damage.
An FAA inspector examined the airplane after it was moved from the accident site. The horizontal stabilizer trim position found at the flight control surface and as indicated on the PFD was consistent with a full nose down setting. The pilot reported that shortly after the accident he observed this trim setting as well.
Examination and tests of the trim rocker switch found that it would move the horizontal stabilizer, however when the switch was released, it would not return to the neutral position as designed. In order to stop the trim movement, the switch needed to be moved to the center position or else it would continue until the maximum nose up/down limit was reached.
The airplane’s operating manual described that pitch trim was accomplished via an electric servo that moved the leading edge of the horizontal stabilizer up and down, changing the angle of incidence. The servo was actuated with a rocker switch located on the control stick.
Review of maintenance records found that the pilot was the mechanic who completed the major repair and alteration and the most recent conditional inspection. The repairs were completed and signed off on June 27, 2022.
According to the FAA inspector who interviewed the mechanic/pilot, he was unable to provide evidence or indication that the trim switch had been inspected for proper operation during the most recent repairs or preflight prior to the flight test.
Probable Cause: The pilot/mechanic’s inadequate inspection of the faulty horizontal stabilizer trim switch, which resulted in an uncommanded trim movement during the takeoff roll, which resulted in an aborted takeoff, and subsequent nose over.
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This July 2022 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
I am not sure if anything has changed in the trim system on the CC11-160 since I flew one a number of years ago, but there was no trim position indicator in the cockpit. There is a visual marking on the horizontal stab, but no way to verify position in the cockpit. The CFI I flew with had experienced a full nose-up trim situation when the front seat pilot had rested their hand on top of the stick and inadvertently pressed the trim to full-up. It seems a lacking system in that configuration but may have been updated as CubCrafters has refined the aircraft.
If you are flying an airplane that has just been flown by several other people during the day with no problems reported, I can see where the trim position verification may be simply a visual check of the indicator in the cockpit. But any other time, especially when the airplane has undergone any maintenance, it’s advisable to move the control to full up and down positions and then to the takeoff position, stopping to visually verify the control surfaces have moved to the correct position at each point even if you have to get out of the cockpit and walk to the rear of the airplane each time. And an understanding of each system is critical – should the trim tab point up, down, or level at each position? Piper and Cessna systems move in opposing directions, so it’s somewhat easy to get them confused.
Unfortunate. Usually you can feel the clicks in that type of switch.