What happened
During a scheduled 200-hour maintenance inspection at the service station at Warsaw Chopin Airport (EPWA), technicians inspecting the exhaust manifolds of a P180 Avanti I identified cracks on the manifold flanges. To verify the extent of the damage, a dye penetrant inspection was performed, which confirmed that the cracks exceeded permissible limits. The damaged manifolds were subsequently removed and sent for repair. Following the repairs, the components were reinstalled on the aircraft, and the aircraft was returned to service.
The investigation
The investigation focused on determining the origin of the structural failures in the exhaust components. The inquiry established that the cracks were a result of technical wear caused by the specific operational profile of the aircraft. The aircraft is frequently utilized for medical missions, which involve a high frequency of short engine cycles relative to total flight hours.
Findings
- The primary cause of the flange cracks was technical wear resulting from specific aircraft operations.
- The nature of medical missions requires frequent engine shutdowns and restarts.
- These frequent cycles subject the manifolds and flanges to intense thermal loading, characterized by repeated heating and cooling phases.
- Because the aircraft often must depart for subsequent missions quickly, the cooling phases are frequently incomplete, leading to high cyclic thermal stresses on the components.