Piper PA 28R-180 N4594J accident near San Jose, California

Probable cause

Maintenance personnel's incorrect installation of the aileron control cables and subsequent failure to verify proper aileron functionality following the maintenance, which resulted in roll control that was opposite of that commanded by the pilot, and the pilot's inadequate preflight inspection, during which he did not verify that the aileron movement matched the control yoke input.

NTSB analysis

The commercial pilot reported that the accident flight was the first flight following maintenance, which included the installation of right-seat rudder pedals with brake controls. The pilot stated that, during a preflight inspection of the airplane, he actuated the ailerons; however, he did not verify which direction the control yoke moved. He again checked the flight control movement before takeoff but did not verify which direction the aileron moved when he moved the control yoke. During the takeoff sequence, as the airplane became airborne, it immediately entered an uncommanded left roll. The pilot attempted to correct for the roll; however, he was unable to do so and subsequently reduced the engine power. The airplane then impacted the ground and came to rest upright on an adjacent runway.

Postaccident examination of the airplane revealed that, when the control yoke was rotated for input of right aileron, the right aileron moved down, and the left aileron moved up, which is opposite of what would be expected. Examination of the aileron cables revealed that they remained attached to the "T" bar aileron control chains; however, the right aileron control cable was attached to the left aileron control chain, and the left aileron control cable was attached to the right aileron control chain; thus, the cables were connected backward.

The cables were oriented such that they crossed underneath the flap handle and center console area. The two mechanics who performed the maintenance on the airplane reported that they had disconnected the aileron control cables to facilitate the installation of the rudder pedals and brake controls. After completing the maintenance, they checked the flight control cable tension and aileron movement; however, they did not observe which direction the control yoke moved when the aileron was moved. It is likely that the mechanics attached the aileron control cables backward during the reassembly of the aileron control system, which resulted in roll control that was opposite of that commanded by the pilot.

Text from the NTSB. Open the NTSB docket for WPR17LA164 for the full record.