Accident Sequence
According to the pilot, during landing the airplane touched down on the runway on all landing gears, bounced slightly, and then touched down on the nose landing gear, causing the nose gear to collapse. The pilot reported that on short final approach, when the airplane was approximately 10-15 feet above the runway, he applied nose-up pitch trim to counter the nose-heavy tendency of the airplane. However, the pitch trim continued to operate in the nose-up direction despite his release of the pitch trim switch. He applied power and forward pressure on the control yoke.
Pitch Trim System Examination
Postaccident examination of the electric pitch trim system revealed that the rocker switches would intermittently stick in either the nose-up or nose-down position. Testing and disassembly of the pilot's electric pitch trim switch showed the unit tested satisfactorily electrically, but intermittent mechanical sticking in either the nose-up or nose-down direction was noted. Dirt and grime were observed near the rocker switch assembly. Examination of both rocker switches found that the hole (pivot point) in one of the two switches measured .001 less than the minimum specification. The pitch trim servo operationally tested satisfactory.
Pilot's Previous Observations
The pilot had purchased the airplane approximately two months earlier and accumulated about 20 hours of flight time. During the last two or three flights, he noted that on eight or nine occasions, the pitch trim continued in the direction of application when using the pitch trim switch on the pilot's control yoke. He corrected this by moving the control yoke opposite the direction of the trim travel and also by moving the pilot's pitch trim switch opposite the initial application direction. Of those eight or nine instances, the trim continued in the nose-down direction six times and in the nose-up direction two or three times. The pilot did not have a mechanic inspect the electric pitch trim system to determine the cause of the trim continuing in the direction of application. On the day of the accident, when the airplane was at an avionics shop for work, he did not mention the trim issue to any personnel.