CEN18LA281

The pilot departed on a postmaintenance check flight after an annual inspection on the previous day. According to the pilot, the airplane was flown in the local traffic pattern before departing the area. As the airplane climbed through 2,500 ft, it was not climbing more than 300 ft per minute without losing airspeed, and the pilot noticed a decrease in engine rpm. The pilot indicated that the oil pressure and oil temperature were normal, the vacuum gauge indicated "zero," and gyroscopic instruments began to drift and tumble. The pilot proceeded directly for the nearest airport, and when on final approach for the runway, the engine rpm and airspeed decreased. The engine did not respond to throttle inputs, and the pilot landed the airplane on a river levy. The airplane bounced, contacted a road, and came to rest against the airport perimeter fence, which resulted in substantial damage to both wings. Examination of the engine revealed that the output shaft of the vacuum pump was sheared. It could not be determined if the vacuum pump output shaft failed before or during the accident sequence. Additional engine information was not available. The reason for the partial loss of engine power could not be determined.

On July 19, 2018, about 0802 central daylight time, a Piper PA28A, N7080F, sustained substantial damage during a forced landing after a partial loss of engine power near the Shreveport Executive Airport (DTN), Shreveport, Louisiana. The commercial pilot, who was the sole occupant, was not injured. The airplane was owned and piloted by a private individual. Visual meteorological conditions prevailed and a flight plan was not filed. The post-maintenance check flight was conducted under the provisions of Title 14 Federal Code of Regulations Part 91. The flight originated about 0730 from DTN. The annual inspection on the airplane was completed on July 18, 2018, and the purpose of the flight was a post-maintenance check flight. According to the pilot, after takeoff from DTN, he stayed in the local traffic pattern and performed two touch and go landings. He proceeded north of the airport and climbed through 2,500 ft; however, the airplane could not attain more than a 300-ft per minute rate of climb without losing airspeed, and he noticed a decrease in engine RPM's. The oil pressure and oil temperature were in the normal operating range, the vacuum gauge indicated "zero," and gyroscopic instruments began to drift and tumble. The pilot proceeded directly for DTN and planning to land on runway 14. On final, the engine RPM's decreased and the airplane airspeed decreased. The engine did not respond to throttle inputs and the pilot was forced to land the airplane on a river levy. The airplane bounced into the air and came back down, contacted a road, and came to rest against the perimeter fence of runway 14. Both wings sustained substantial damage. Examination of the engine by a Federal Aviation Administration inspector revealed that the output shaft of the vacuum pump was sheared. The pilot did not submit the National Transportation Safety Board Accident Report Form 6120, and additional engine information was not available. The reason for the vacuum pump output shaft failure and partial loss of engine power was not determined.