What happened
On October 12, 2014, a privately owned Piper PA-28R-201T, registered JA59FB, was conducting a familiarization flight from Akita Airport to Chofu Airfield. The flight was operated under Visual Flight Rules (VFR) with a pilot and two passengers on board.
During the flight, the aircraft's alternator failed. The pilot, seated in the right front seat, did not immediately realize the extent of the electrical issue, partly because the alternator annunciator light failed to illuminate and the ammeter was difficult to monitor from his position. Upon noticing the ammeter reading zero, the pilot attempted to reset the alternator switch and subsequently shut down non-essential electrical equipment to preserve battery life.
As the aircraft approached Chofu Airfield, the pilot requested a passenger to operate the landing gear lever. Although the gear position indicators failed to illuminate, the pilot assumed the gear had successfully extended and that the lack of indication was simply due to low battery voltage. Consequently, the pilot did not perform the emergency gear extension procedure outlined in the Airplane Flight Manual. During the landing on runway 17, the aircraft struck the runway on its belly, resulting in substantial damage to the airframe, flaps, and propeller blades. There were no injuries to the three occupants.
The investigation
The Japan Transport Safety Board (JTSB) examined the aircraft's electrical systems, the battery, and the landing gear operation. Investigators performed tests on the radio communication equipment and the electrical continuity of the annunciator lights. The investigation also reviewed the pilot's flight logs, the aircraft's maintenance history, and interviewed the pilot, passengers, and a witness from the control tower.
Findings
- The primary cause of the accident was the failure to perform the emergency landing gear extension after the normal extension procedure failed to show positive indicators.
- The pilot's failure to execute the emergency procedure was driven by the incorrect assumption that the gear was already down and that the lack of lights was a symptom of the electrical failure.
- The recognition of the alternator failure was delayed because the annunciator light failed to illuminate and the ammeter was poorly positioned for the pilot in the right seat.
- The pilot's personal checklist did not include procedures for alternator failure or emergency gear extension.
- A passenger, who was a certified pilot, noticed the lack of typical vibration or noise during gear extension but did not alert the pilot to this anomaly.