Mooney M20E N5895Q accident near Stillwater, Oklahoma

Probable cause

The inadequate maintenance and inspection of the engine induction air coupling, which impeded airflow to the engine and resulted in the subsequent partial loss of engine power.

NTSB analysis

The pilot reported that, during cruise flight, the engine lost partial power, which necessitated an emergency landing on a highway. During the landing, the airplane impacted a road barrier, which resulted in substantial damage to the left wing.

During a postaccident examination, the induction air coupling was found wrapped in gray tape. When the tape was removed, separations were visible on the top and bottom at the flange on the inboard side. The top and bottom separations likely reduced the rigidity of the coupling when the engine was operating. Examination of the inside of the coupling showed that the lower portion appeared to be permanently deformed in a manner similar to compression. Therefore, because of the reduction in the coupling’s rigidity, the coupling had likely closed due to suction from the engine, which impeded airflow.

Tape should not have been applied as a fix for the induction coupling separations. The investigation could not determine when the coupling separations appeared or the tape was applied, but those events had likely caused the permanent deformation to the coupling. The airframe and powerplant mechanic, who performed annual inspections for the airplane during the 3 years before the accident. should not have allowed the airplane to return to service with the tape applied and the coupling deformed.

Text from the NTSB. Open the NTSB docket for CEN22LA255 for the full record.