Accident Details
On March 16, 2020, at approximately 1720 mountain daylight time, a Piper PA-22-108, registration N4837Z, was substantially damaged when it collided with terrain near Pinedale, Wyoming. The aircraft was operating as a Title 14 Code of Federal Regulations Part 91 instructional flight. The student pilot sustained minor injuries, while the flight instructor was seriously injured.
Pilot Reports
The student pilot reported that during the final approach to runway 29, the flight instructor took control of the airplane because it was drifting to the right. The flight instructor later stated that after assuming control, he applied rudder control inputs. He noted that over a period of 6 to 7 seconds, the rudder pedals would not move. The airplane failed to align with the runway and shortly after impacted the ground near the runway.
Aircraft Examination
An airframe and powerplant mechanic examined the recovered airframe and found substantial impact damage to both wings, the fuselage, and the engine mount. The left wing, from the side strut to the tip, was partially separated due to ground impact. The left aileron inboard attachment bracket had separated from the left aileron bellcrank. Corrosion was observed between the aileron bracket and aileron bellcrank mounting surfaces. The remaining rivet material in the aileron and bellcrank bracket exhibited overload necking signatures. The flight control cables were intact.
Examination of the rudder control system revealed that the rear pulleys could not be rotated freely by hand. However, during a control cable continuity check, the cables moved past the pulleys with little resistance. Nothing was found impeding the rudder pedals from their normal movement. In a subsequent examination, the pulleys were stiff when rotated by hand, and the cables were undamaged.
The flight instructor speculated that the glareshield-mounted tachometer timing box might have become trapped behind the rudder pedals. The tachometer timing box was located at the accident site and had been thrown from the wreckage. A portion of the instrument panel-mounted tachometer housing was found behind the rudder pedals. Further examination of the tachometer gauge revealed damage consistent with impact forces from the accident.
An NTSB Form 6120.1 Pilot/Operator Aircraft Accident/Incident Report was not submitted by the student pilot or the flight instructor.