Background
On February 20, 2023, at 1425 Pacific standard time, a Piper PA24-260, registration N9267P, experienced a landing gear malfunction that led to structural damage during the landing rollout at Reid-Hillview Airport (RHV) in San Jose, California. The aircraft was operating under Title 14 Code of Federal Regulations Part 91. The pilot and the sole passenger were not injured.
Flight
The pilot had departed from RHV en route to Half Moon Bay Airport (HAF). After an uneventful flight, during the landing approach, he performed pre-landing checks and noticed the landing gear had not extended. The landing gear indicator light was not green, and the emergency extension handle had not moved to the landing position. He cycled the landing gear switch without success, aborted the landing, and flew over the ocean to troubleshoot. The circuit breaker had not tripped and did not feel hot. Another cycle of the switch failed to extend the gear.
Deciding to return to RHV where maintenance services were available, the pilot released the emergency release arm per procedures, but the gear remained retracted. The telescoping emergency extension bar was jammed. He then executed a series of high-G maneuvers while pushing the extension handle; after multiple attempts, the handle moved forward to what appeared to be the fully extended position, but the green light did not illuminate. Controllers at San Jose International Airport and RHV confirmed the gear appeared down.
The landing was uneventful until the pilot retarded the throttle, at which point the nose gear began to retract, followed by the main gear. The subsequent ground roll caused structural damage to both lower center beams and multiple bulkheads.
System Description
The aircraft was equipped with a retractable tricycle landing gear operated via an electrically controlled system. An electrical motor and transmission drove a torque tube and bellcrank connected to push-pull cables for each gear strut. All three gear moved simultaneously and were locked by over-center links. An emergency release arm could disconnect the motor for manual extension using the emergency extender bar.
Examination
Post-accident examination by the National Transportation Safety Board revealed that the landing gear motor intermittently stopped in the retracted position without tripping the circuit breaker. The transmission jackscrew assembly was greased and showed no binding; the motor emitted no smoke. No maintenance records indicated the motor had been replaced.
The emergency gear release system showed wear on the pivot pins and holes of the disengage arm and links, reducing leverage to consistently release the motor transmission. When the motor remained connected, it inhibited bellcrank movement, preventing manual extension. Even when the mechanism released, a worn and out-of-adjustment drag link assembly in the nose gear allowed the nose gear to unlock under forward force, which also unlocked the main gear. This condition was masked during normal operation by the motor driving the drag links into lock.
The entire landing gear system was dirty and coated with old grease and grime. The nose landing gear drag link assemblies were slightly loose at their fuselage fittings.
Maintenance
Airworthiness Directive (AD) 77-13-21, issued in 1977, was designed to prevent landing gear collapse after manual extension. It required a specific inspection at 1,000-hour intervals, installation of a second nose gear downlock spring per Piper Service Letter 782, and periodic main gear bungee cord inspection with replacement at 500-hour intervals. The last inspection was completed in 2007, with 306 hours remaining until the next due interval. The second spring was installed, and the bungees were replaced in June 2020, 78 flight hours before the accident. The mechanic who performed the most recent annual inspection one week prior stated he conducted a functional check of the landing gear on jacks with no anomalies noted.
The aircraft maintenance logbook indicated compliance with FAR Part 43 appendix D, which includes inspection of landing gear components for poor condition, excessive wear, and improper operation.