Background
On 17 September 2020, an ATR 72 aircraft, registration SP-SPD, operated a flight from Basel (LFSB) to Cologne (EDDK). After arrival, a technician inspecting the aircraft discovered damage to the compressor blades of engine No. 2 (type PW127F) that exceeded permissible limits. Flight data recorder parameters from recent flights were within normal ranges.
Findings
On 19 September 2020, an external company (4Thrust) performed a boroscopic examination of the engine and confirmed damage to the low-pressure and high-pressure compressor blades and the compressor casing. The engine was subsequently removed and sent to the StandardAero overhaul facility in France.
On 26 October 2020, StandardAero provided a detailed report describing all damage. The most significant damage was found on the low-pressure centrifugal compressor blades. The high-pressure compressor exhibited only minor damage. The rear compressor inlet showed substantial material loss and abrasion marks. According to StandardAero, the damage was consistent with impact by a metallic object. No foreign objects or their traces were found in the gas path.
Technical personnel inspected the air intakes, engine nacelle, propeller, and other airframe components within the zone where a foreign object could have entered the engine. No damage or missing parts were detected. Crew actions during engine runs, taxi, and takeoff were reviewed and found to be correct. The operator also reviewed available airport camera footage but observed no actions that could have contributed to the incident.
Cause
The cause of the incident was ingestion of a foreign object, likely a metal object, which caused damage to the low-pressure and high-pressure compressor blades and the compressor air intake.
Contributing Factors
No contributing circumstances were identified.
Preventive Actions and Safety Recommendations
No preventive actions were proposed, and no safety recommendations were issued by the investigating body.