What happened
On September 24, 2010, at 20:58 UTC, a Piper PA-34-200, registration PT-IHI, departed from Salgado Filho Airport (SBPA) in Porto Alegre, Brazil, for a local instructional flight. The aircraft was operated by Born to Fly Escola de Aviação Civil with two crew members on board.
Shortly after departing from runway 11, the left engine failed. The instructor in command immediately declared an emergency, banked the aircraft to the left to facilitate a return to the airfield, and successfully performed a landing on runway 2/29. There were no injuries to the crew and no damage was sustained by the aircraft.
The investigation
The investigation focused on the mechanical failure of the left engine, an IO-360-C1E6. At the time of the incident, weather conditions were favorable, and the aircraft was within its approved weight and balance limits. The engine had undergone a major overhaul approximately 1,591 hours prior to the event.
Upon inspection of the engine, investigators discovered a crack in the upper part of the engine block near the fuel distributor valve. The engine was found to be seized, showing signs of internal damage. Detailed disassembly revealed a discrepancy in the alignment of the engine block halves. Specifically, at the junction supporting the crankshaft, the block was not perfectly seated, and the surface exhibited roughness and cracks indicative of significant vibration. This misalignment led to the subsequent failure of the crankshaft.
Findings
- The primary cause of the engine failure was an engine block crack and misalignment.
- The engine block halves were not properly seated, creating a point of origin for the fracture.
- Evidence of vibration-induced wear was present on the engine block surfaces.
- Maintenance-related factors and organizational oversight at the maintenance facility were identified as contributing factors.
Safety action
Following the investigation, safety recommendations were issued to the National Civil Aviation Agency (ANAC) regarding the maintenance facility involved. The recommendations urge ANAC to ensure that the workshop adheres strictly to manufacturer-specified overhaul procedures and maintains adequate managerial supervision over its maintenance services.