Mooney M20 N242TS accident near Pottstown, Pennsylvania

Probable cause

The pilot’s inadequate preflight inspection, which resulted in a total loss of engine power due to fuel contamination and a subsequent off-airport landing.

NTSB analysis

The accident flight was the airplane’s first since its annual inspection, which had just been completed. According to the pilot, because the airplane had just undergone an annual inspection, he completed a thorough preflight inspection, including checking and draining fuel from the fuel sumps. The pilot stated that, after the preflight, he then started the engine and completed two runups before taxiing to the runway for takeoff.

According to witnesses and the pilot, the airplane’s takeoff was normal. The pilot reported that everything appeared to be normal until reaching 300 to 400 ft above ground level (agl), when the engine suddenly stopped producing power. A witness reported hearing the engine "cut out" then "surge." The witness also stated that the airplane began a right turn about 300 ft agl and appeared to stop climbing at this point while the turn appeared to become steeper. The pilot stated that he knew he would not be able to safely return to the airport and veered the aircraft to the right to avoid any property or people who might have been straight ahead, aiming for the grassy area just to north side of the runway, where the airplane struck the ground and came to rest.

Examination of the airplane and engine revealed no evidence of any preimpact failures or malfunctions that would have precluded normal operation. However, examination of the fuel system revealed the presence of water in the fuel system and carburetor float bowl, which likely caused the engine power loss.

The mechanic who performed the airplane’s most recent annual inspection reported completing several static power engine runups the day before the accident; the engine produced power during each runup, and he did not note any abnormalities. He stated that the airplane had been at the airport for about 2 weeks before the accident flight and was subject to several heavy rain events during that period. He also stated that the airplane had not been refueled since it had arrived at the airport for maintenance. Review of fuel provider records from the location of the airplane’s last known refueling did not reveal any evidence of contamination of the fuel provider’s fuel supply.

The owner’s airplane manual stated that the fuel sumps should be drained as part of the preflight inspection. It is likely that the pilot rushed or did not perform the preflight, as water was discovered in the fuel system.

Text from the NTSB. Open the NTSB docket for ERA16LA126 for the full record.