Accident to the Piper PA25 registered F-HPMO on 05/09/2021 at Bedous

During the aeroplane’s last “50-hour” inspection, the mechanic carried out a temporary repair to the exhaust system by adding high-temperature-resistant tape and an aluminium sheet. He did not realise that the temperature resistance of the sheet used for this repair was lower than the temperature reached by the exhaust, making this repair inappropriate. In addition, he did not seek the advice of the workshop that usually ensured the aeroplane follow-up, nor did he use any supporting documents.

During the third flight after this repair, the pilot at the controls detected a smell of heat and aborted the flight. After landing, he reported the problem to another pilot, who knew about the repair. As they were unable to contact the mechanic, they carried out a brief inspection of the engine together and did not find any damage. The second pilot then decided to perform the subsequent flight himself to see if the problem persisted.

During the flights which followed the repair, the aluminium sheet melted, gradually damaging the wiring under the exhaust. During the accident flight, damage to the magneto grounding cables resulted in a reduction in engine power. The pilot decided to make an emergency landing. Despite the throttle lever being set to the “idle” position, the damage to the grounding cables of both magnetos developed until the engine electrical supply cut off and the engine shut down while the aircraft was on final. The pilot had to land in the field located before the one he had chosen. During the run, he did not manage to stop the aeroplane before the line of trees separating the two fields, and the aeroplane collided with the trees.

In the absence of the results of the further examination of the engine by the workshop responsible for its return to service, it was not possible to confirm whether the engine had also run at an abnormally high temperature, as the findings observed after the engine disassembly may suggest.