Piper Aircraft Inc PA-28-181 N504AF accident near Addison, Texas

Probable cause

A partial loss of engine power during takeoff due to the partial blockage of the fuel diaphragm metering stem and the No. 1 cylinder fuel injector nozzle. Contributing to the accident was maintenance that allowed the introduction of debris that resulted in the blocked fuel system.

NTSB analysis

The pilot reported that, about 150 ft above ground level during the initial climb, the engine lost partial power. Unable to continue the climb, the pilot declared an emergency and attempted to land on the remaining usable runway. The airplane landed hard and the right main landing gear collapsed, which resulted in substantial damage to the right wing.

Postaccident examination of recorded engine data showed evidence that the engine’s No. 1 cylinder had reduced fuel flow at the time of the accident. Further examination revealed grayishwhite foreign object debris in the fuel diaphragm metering stem and in the No. 1 cylinder fuel injector nozzle. The debris was consistent with the sealant found on the male threads of the attachment fittings for the fuel flow transducer.

Based on the available information, the sealant was likely inadvertently introduced into the fuel line when the fuel flow transducer was replaced the week before the accident. According to the mechanic who performed the maintenance, he removed the sealant following the maintenance instructions provided by the manufacturer. The post maintenance test run was completed without issue. The sealant debris likely migrated to the diaphragm metering stem and fuel injector nozzle, which resulted in a partial blockage, and subsequent restricted fuel flow to the engine during the initial climb and the partial loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN25LA077 for the full record.