Piper PA-34-200T accident at Nîmes Garons due to total electrical failure and landing gear retraction

Incident Overview and Flight Details On 5 June 2011, a Piper PA-34-200T Seneca II, registration HB-LSD, operated by a private pilot, departed Son Bonet aerodrome in Spain at 13:45 local time. The aircraft was carrying three passengers and was en route to Basel-Mulhouse under instrument flight rules (IFR). Approximately one hour into the flight at flight level 110, the pilot observed that the left engine electrical charge indicator was near zero, while the right engine indicated approximately 35 amperes. After attempting to reset the alternators, the left indicator remained unchanged and the right dropped to 30 amperes. ## Electrical Degradation and Emergency Procedures The pilot shed electrical load, retaining only COM1, NAV1, the transponder, and the GPS. About 20 minutes later, the flight director began providing erroneous information, prompting the pilot to disengage the autopilot. Two minutes later, approximately 50 nautical miles from the Martigues VOR, the pilot activated the weather radar due to deteriorating conditions. Shortly after, the right alternator charge dropped to 5 amperes and the ALT warning light illuminated intermittently. The pilot shed further load, keeping only the transponder and one radio, after which the aircraft experienced a total electrical failure. ## Approach and Landing at Nîmes Garons Ten nautical miles from the Martigues VOR, the pilot descended to 1,000 feet to pass beneath the cloud layer. Unable to notify air traffic control, the pilot initially attempted to reach Avignon aerodrome for repairs but encountered a thunderstorm barrier and diverted to Nîmes Garons. While configuring for landing, the pilot was unable to operate the mechanical emergency gear extension handle. With the storm approaching, the pilot decided to land with the landing gear retracted. ## Meteorological Conditions and Pilot Experience At the time of the accident, the weather at Nîmes Garons included a wind from 260 degrees at 2 knots, visibility greater than 10 kilometers, thunderstorm cells in the vicinity, and a temperature of 19 degrees Celsius. The pilot held 2,634 total flight hours, including 1,212 hours in IFR, 52 hours in the preceding three months, and 40 hours in the previous month, of which 26 were on type. ## Investigation Findings Examination of the landing gear revealed no malfunction during the emergency extension attempt. The procedure requires manipulating a metal cover before operating the emergency handle. The left engine alternator had been replaced on 18 May 2011. Prior to the flight, the pilot had requested maintenance to check both alternators due to differing charge indications. The maintenance technician attempted to adjust the alternator charges but was unable to do so satisfactorily and planned to continue the work after the flight. Post-incident examination showed that a component of the drive mechanism was broken in each alternator. ## Conclusion The accident was caused by the pilot's inability to extend the landing gear in emergency mode. Under stress in difficult conditions, the pilot was unable to fully apply the emergency gear extension procedure. The total electrical failure was linked to the double rupture of a drive mechanism component in each alternator. The cause of this double failure could not be determined.