What happened
On March 26, 2000, a private Piper PA-46 310 P Malibu, registered F-GHRR, was conducting a cross-country flight from Moulins toward Toussus-le-Noble. While cruising at flight level 180, the pilot experienced a loss of engine power. The aircraft was flying through clouds approximately 15 nautical miles from Nevers, with an outside air temperature of -25 °C.
Upon noticing the power loss, the pilot notified air traffic control and requested a diversion to Nevers, the most suitable nearby aerodrome. During the descent, the pilot monitored engine parameters and noted that manifold pressure, fuel flow, and cylinder temperatures had dropped to zero, while the propeller RPM stabilized at 1500. The pilot activated the transponder emergency code 7700 while passing through flight level 90. Guided by Avord Approach, the aircraft descended toward the Nevers runway centerline with the engine significantly degraded. As the aircraft descended through the cloud base to approximately 1000 feet, the engine regained power. The pilot successfully landed on runway 12 at Nevers, where the engine was observed to be operating normally after the aircraft had come to a stop.
The investigation
The investigation focused on the cause of the engine power loss and the mechanical state of the air intake system. Investigators examined the engine parameters recorded during the descent and reviewed the aircraft's maintenance history regarding the air intake system. It was noted that the pilot had utilized the alternate air function during the climb and cruise phases of the flight.
Findings
- The primary cause of the engine power loss was icing of the air intake housing.
- The investigation revealed that several Service Bulletins (Nos. 852, 895, and 961) regarding necessary modifications to the alternate air system had not been implemented on the aircraft.
- These specific bulletins were issued to address similar icing-related power loss issues.