What happened
During flight, the crew of VH-PSU experienced loud bangs and smoke emanating from the engine. This event prompted the flight crew to initiate a precautionary descent and return to the departure aerodrome to ensure safety.
The investigation
The investigation focused on the mechanical failure within the engine's low-pressure compressor (boost) rotor. Analysis revealed that a single aerofoil on this rotor had fractured. The failure was traced back to a fatigue crack that began at the trailing edge on the pressure side and moved toward the leading edge before the final fracture took place. While the investigation could not pinpoint the exact origin of the crack, the damage was consistent with high-cycle fatigue.
Findings
- The primary cause of the event was the failure of a single aerofoil on the low-pressure compressor rotor due to high-cycle fatigue cracking.
- The JT15D-5D engine's boost rotor has a documented history of aerofoil distress.
- Although previous measures had been implemented to address similar issues, the engine manufacturer has now initiated further research to better understand the mechanisms behind this type of distress.