What happened
On June 19, 2017, at approximately 14:00 LMT, a crew was conducting a post-maintenance test flight following a "C + HSI" inspection performed by a maintenance station in Germany. The aircraft, a P180 Avanti II, was being evaluated for engine performance parameters in flight. During the procedure, the crew identified a loss of performance in the left engine, accompanied by a significant difference in interstage turbine temperatures between the left and right engines.
The aircraft landed safely at EDLN without further incident. After taxiing to the parking apron and handing the aircraft over to the maintenance facility, the operator notified a Dutch maintenance company that had previously performed hot section inspections on the engines for the German station. Upon inspection of the left engine by the Dutch company, physical damage was discovered, including abrasions on the external upper edges of the compressor blades and abrasions on the internal surfaces of the compressor casing.
The investigation
The investigation involved coordination between the PKBWL and the German BFU. The PKBWL issued an Event Notification to the BFU in July 2018. In response, the BFU stated they were unaware of the event and would provide updates on further actions. Following a follow-up inquiry by the PKBWL in February 2018, the BFU indicated that they had not initiated a formal investigation into the incident.
Findings
- The primary technical issue involved abrasions on the compressor blades and compressor casing within the left engine.
- The engine performance degradation and temperature discrepancies were directly linked to the identified internal compressor damage.