Accident Details
On August 5, 2024, about 0900 Pacific daylight time, a Piper PA-34-220T, registration N4145B, was substantially damaged when it was involved in an accident near Minden, Nevada. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
Pilot Report
The pilot reported that the purpose of the flight was to conduct a maintenance check flight following an annual inspection. During the preflight inspection, he conducted a functional check of the stabilator trim with the electric trim control. He heard the trim motor working; however, he did not visually verify the stabilator trim position. During the takeoff roll, he pulled back on the yoke at the rotation speed of 80 knots, but there was no change in pitch, so he pulled harder. He used the electric trim and had minimal elevation gain. He aborted the takeoff by closing both throttles. The airplane pitched forward, porpoised about four times, and the landing gear collapsed.
The airplane’s pilot operating handbook preflight checklist states: “Stabilator & Rudder trim…. Neutral.”
Examination Findings
Postaccident examination of the airplane revealed buckling and bending on the forward fuselage near left and right wing. Buckling and bending was also observed above the windscreen on the fuselage. The stabilator trim wheel indicator was found in the full nose-down position.
A visual examination of the flight control cables was conducted, and no damage was observed. Flight control continuity was established from the cockpit flight controls to the respective flight control surfaces.
Subsequent examination of the stabilator trim wheel revealed binding. Force was needed to rotate the stabilator trim control wheel to the neutral position when rotated by hand. Using the airplane’s battery, power was applied to the electric trim controls. When the stabilator trim was placed in the full nose-down position, the electric trim servo was heard operating but would not move the stabilator trim cable. A visual examination of the stabilator trim control cable was conducted; no damage was observed. The empennage flight control cover was removed, and a visual inspection of the trim screw assembly was conducted. Corrosion was observed on the trim screw assembly. The exposed shaft of the trim screw was free of lubrication; the ends exhibited minimal lubrication. The trim screw assembly had radial and axial play when moved by hand, consistent with excessive wear on the upper-and lower-barrel mount bearings. The trim screw assembly was disassembled, and circular grooves were observed on the outer sections of the upper-and lower-barrel mount bearings.
Maintenance Background
According to the mechanic who conducted the annual inspection, no anomalies were noted with the flight controls or the stabilator trim controls. The mechanic’s normal process to check and lubricate the stabilator trim controls was to run the stabilator trim to the full nose-up position, lubricate the stabilator trim shaft, and then run the stabilator trim to the full nose-down position. During the exam of the stabilator trim shaft, he operated the stabilator trim controls, and his apprentice lubricated the stabilator trim shaft.
The apprentice who assisted in the annual inspection reported that he did not recall lubricating the stabilator trim controls. Additionally, he did not conduct a functional check of the stabilator trim controls.
According to the manufacturer’s maintenance manual check list, the scheduled maintenance of the fuselage and empennage group stated, “Inspect aileron, rudder, stabilator, and stabilator trim cables and pulleys for routing, safety, condition, and operation. Inspect cable terminals, turnbuckles, guides, and fittings for safety and condition.” The lubrication chart in the maintenance manual also identified that the rudder, stabilator, and trim control wheels be lubricated every 100 hours.