N3700HMooney M20J · 1980

On August 24, 2013, about 1030 eastern daylight time, a Mooney M20J, N3700H, was substantially damaged when it impacted swampy terrain during a takeoff attempt from Marco Island Airport (MKY), Marco Island, Florida. The airline transport pilot sustained minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the flight, to Wing South Airpark (FA37), Naples, Florida. The personal flight was operating under the provisions of 14 Code of Federal Regulations Part 91.

According to the pilot, he set the flaps at 15 degrees for takeoff, and the flap indicator and trim indicator next to each other appeared to line up, which was normal. However, during the takeoff, at an approximate rotation speed of 63 knots indicated, the airplane pitched up more rapidly than normal and the stabilizer trim did not seem to be working.

The event occurred so suddenly that the pilot did not have an opportunity to abort the takeoff with a power reduction. "It was an uncommanded pitch-up and the yoke would not respond to counteract the pitch and turn The rudder and ailerons were stuck in the neutral position and would not move in the direction to initiate a right counteracting turn. Although the left turning tendencies are well known on takeoff with high power and angle of attack ("P" factor, torque and slipstream affect all work together requiring lots of right rudder), something caused the stab trim to go forward and prevent the normal rudder and aileron coordination for a turn to the right to counteract the left turning tendencies."

The airplane then descended into the swamp to the left of the runway.

According to the pilot's operating handbook (POH), "Push-pull tubes with self-aligning rod end bearings actuate the primary flight control surfaces. A spring-loaded interconnect device indirectly joins the aileron and rudder control systems to assist in lateral stability during flight maneuvers."

In addition, "For pitch control, the entire empennage pivots on the tail cone attachment points to increase or decrease the horizontal stabilizer angle. This design allows flight trim establishment with minimum control surface deflection. A trim indicator on the console indicates stabilizer trim position. In flight, forward rotation of the trim wheel lowers the nose; rearward rotation raises the nose."

A photograph of the trim/flap annunciator taken at the accident site by a Federal Aviation Administration (FAA) inspector showed separate indicators for each, with positions noted as "Down", "Takeoff" and "Up." The flap indication was in the "Takeoff" position, while the trim indication was in the "Up" position. A corner of the photograph also showed the autopilot controller, which indicated the autopilot as being "Off."

According to a representative of Mooney, and as verified in the M20J Illustrated Parts Catalog, trim position was established via a "trim screw assembly" (worm drive) which would not have been movable as a result of ground impact. The representative also noted that according to a company engineer, earlier models of the airplane "could jam if the trim was electrically or manually run hard up against the stops. The jack screw and jam nuts have since been re-designed to resolve the issue."

After the airplane had been moved to a storage facility, the FAA inspector tested the trim electrically to the stops and noted no binding.

According to the pilot, he was a partial owner of the airplane and the only one to fly it. He did not run the trim to the stops during the preflight checks, and he didn't know why the trim would have been in the "Up" position.

Per the M20J Pilot Operating Handbook, Before Takeoff checklist, "Trim – Takeoff Setting."