The private pilot, who was conducting a cross-country flight, entered the downwind pattern at his home airfield in Nacogdoches, Texas, and prepared the Mooney M20 to land using the manufacturer’s checklist, which included selecting the fullest fuel tank, setting flaps to 5°, and lowering the landing gear.
While on an extended downwind leg, he noticed that the plane had descended to between 700′ and 800′ above ground level, so he added engine power to climb back to pattern altitude, but the engine stopped producing power.
The pilot turned the airplane toward the runway, which he estimated was more than 1.5 miles away. He realized he was not going to be able to glide to the runway, so he performed a forced landing to a field but landed short in a wooded area.
Examination and testing of the engine did not reveal any anomalies that would have precluded normal operation.
Maintenance had recently been conducted on the fuel selector’s union fitting. The mechanic who conducted the maintenance reported purging the lines of air and conducting a successful post-maintenance test flight before releasing the airplane to the pilot. The reason for the loss of engine power could not be determined.
Probable cause: The loss of engine power for reasons that could not be determined because post-accident examination and testing of the engine did not reveal any anomalies that would have precluded normal operation.
NTSB Identification: CEN17LA068
This January 2017 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.

The secondary cause was the B52 pattern being flown.