What happened
On June 7, 2023, a Piper 34-200T, registration HK-5025, was performing a maintenance ferry flight from Paipa to Medellín, Colombia. During the flight, the crew identified a failure in the electrical system that initially affected the left-side equipment before progressing to a total system failure. This loss of electrical power resulted in a communications blackout, leaving the aircraft in a NORDO (no radio) condition.
While the crew was unable to communicate via radio, they managed to use a mobile phone to alert Medellín tower of their situation via another aircraft in the vicinity. Due to the electrical failure, the electro-hydraulic motor responsible for the landing gear could not be activated. The crew attempted to manually extend the landing gear following the Pilot's Operating Handbook (POH) procedures. However, they were unable to confirm the nose gear was locked, and another nearby aircraft notified them that only the main gear had deployed.
Deciding to land, the crew approached runway 02 at Olaya Herrera Airport with the nose gear retracted. Upon touchdown, the nose gear made contact with the runway surface, causing substantial damage to the aircraft and the pavement. The aircraft's engines suffered sudden stops due to propeller contact with the asphalt. The two crew members evacuated the aircraft safely without injuries.
The investigation
The GRIAA investigation focused on the electrical failure and the subsequent failure of the manual gear extension. Investigators examined the electrical system, specifically the alternator and the fuse pinion. The investigation also reviewed maintenance records, the crew's recent flight experience, and the operational procedures used during the emergency.
Findings
- The primary cause of the incident was the execution of a landing with the nose gear retracted following a failure of the gear to extend during the emergency procedure.
- The electrical system failure was caused by a deficiency in the alternator's fuse pinion on the No. 2 engine, which prevented the conversion of mechanical energy into electrical current.
- The crew failed to identify the failure of the No. 2 alternator through proper monitoring, leading them to disable the entire electrical system to prevent short circuits.
- The investigation could not conclusively determine why the nose gear failed to extend via the manual free-fall valve, though factors such as high airspeed during the attempt or potential obstructions in the gear well were considered.
- The operator lacked sufficient procedures for managing flight transitions for crews with low recent experience and lacked robust risk management for ferry flights.