CEN25LA077

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 grayish white 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.

On January 14, 2025, about 1830 central standard time, a Piper PA-28-181 airplane, N504AF, was substantially damaged when it was involved in an accident near Addison, Texas. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that during the initial climb, about 150 ft above ground level, 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, the right main landing gear collapsed, and the airplane came to a stop upright. The right wing sustained substantial damage. Recorded engine data for the accident flight indicated a sudden increase in the exhaust gas temperature (EGT) for cylinder No. 1, followed by a drop, during the takeoff. Postaccident examination of the engine revealed that it appeared to be undamaged and remained attached to the airframe. Several engine functional test runs were conducted during the examination. The engine started, idled, and operated without hesitation at full throttle, both with and without the electric fuel pump activated. The engine stabilized at 1,800 rpm and a magneto check was performed. When the left magneto was selected off, there was a decrease in power of about 70 rpm rpm. When the right magneto was selected off, there was a drop of about 50 rpm. With both magnetos selected on, the engine produced about 2,350 rpm at full power. During subsequent test runs, high EGT was observed on cylinder No. 1. The EGT probes from cylinder Nos. 1 and 3 were swapped; however, the high EGT indication remained with cylinder No. 1. The fuel injector nozzle lines were then disconnected from the fuel injectors, and fuel flowed through each line using the electric fuel pump. Fuel captured from each nozzle was observed to be of about equal quantity. The fuel injector nozzle for cylinder No. 1 was removed and inspected; grayish white foreign object debris (FOD) was found. The contaminant was removed, and the engine was test run again; however, high EGT on cylinder No. 1 was observed. During subsequent testing, operation lean of peak resulted in elevated EGT indications on all four cylinders. When the mixture was enriched to rich of peak, EGT values decreased on all cylinders except cylinder No. 1, which remained elevated. The fuel flow divider cap and metering stem were then removed and inspected. A larger piece of grayish white FOD was found partially obstructing the port corresponding to cylinder No. 1. The fuel flow transducer was examined and the sealant found on the attachment fittings was consistent with the FOD found in both the fuel injector nozzle and the flow divider metering stem. The FOD was removed from the fuel flow divider metering stem and the fittings at the fuel flow transducer were removed and cleaned until no sealant residue remained. During subsequent test runs, the engine was operated across a range of powersettings from idle (about 750 rpm) to full power (about 2,350 rpm). No anomalies were noted, and EGT indications were approximately equal across all cylinders at various throttle and mixture settings. A review of the maintenance records revealed that the fuel flow transducer was removed and replaced a week before the accident, on January 8, 2025. The tachometer time listed in the maintenance record entry was 4,880.1. The tachometer, as observed at the start of the examination, was 4,899.8. The mechanic who completed the maintenance reported that he performed all maintenance in accordance with the approved maintenance manual for the Piper PA-28-181, including the most recent revision. He stated that the maintenance was performed because a pilot reported that the fuel flow gauge was indicating erroneous readings at idle and full throttle. The mechanic reported that he cleaned the attachment fittings and removed the old sealant before installing the new fuel flow transducer in accordance with the maintenance manual. After completing the maintenance, he performed an engine ground run and all operational tests were satisfactory.