Cessna 172K N46459 accident near Neenah, Wisconsin

Probable cause

A loss of engine power due to oil starvation, which resulted from the pilot, who was not a certified airframe and powerplant mechanic, removing the vacuum pump from the engine, and his misconception that he could operate the airplane without the pump.

NTSB analysis

The private pilot was conducting the first flight in the airplane after having removed a failed vacuum pump from the engine; the pilot was not a certified airframe and powerplant mechanic. During the flight, the engine lost power, and the pilot subsequently landed the airplane on a highway, and the left wing contacted a road sign, which resulted in substantial damage.

The pilot reported that he had recently had a mechanic remove a failed vacuum pump on a different airplane that he owned and that he was able to fly that airplane without the pump. As a result, he thought he could also fly the accident airplane without a vacuum pump. However, the vacuum pumps were mounted on each airplane differently, and the pilot's removal of the vacuum pump on the accident airplane allowed oil to exit the engine through the drive gear opening on the accessory case, which resulted in oil starvation.

Text from the NTSB. Open the NTSB docket for CEN16LA309 for the full record.