Piper PA32 N4089R accident near Tallahassee, Florida

Probable cause

A partial loss of engine power on takeoff due to an intermittently blocked fuel injector on the number 3 cylinder.

NTSB analysis

The pilot performed a preflight inspection of the airplane with no anomalies noted; during the engine run-up, the engine backfired. The pilot continued the run-up procedures and did not have any other issues with the engine. After rotation, the pilot noticed that the tachometer did not indicate full engine rpm, and also noted that the engine was not producing power. Since the airspeed was slow, he attempted to decrease the pitch of the airplane; however, the airplane was already in an aerodynamic stall, which resulted in impact with the runway. The airplane departed the right side of the runway and impacted the visual approach light system lights, resulting in substantial damage to the right wing.

A postaccident examination and test run of the engine revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. A review of data extracted from the airplane’s engine data monitor data revealed that the number 3 cylinder began performing erratically beginning around 7 minutes after the recording began, likely as the airplane was being taxied, and continued through the run-up described by the pilot. This erratic behavior initially appeared as rapid increases and decreases in exhaust gas temperature (EGT) that differed dramatically from the behavior of the other 5 cylinders. Then, about 3 minutes after the erratic EGT temperatures began, the number 3 cylinder head temperature (CHT) began steadily decreasing, while the remaining 5 cylinders continued their gradual increase. The takeoff likely began about 11 minutes and 30 seconds after the data recording began, as the engine rpm increased to about 2,400 (which was less than the maximum 2,700 rpm that was observed during the three previous takeoffs that were recorded).

Given this information, the most likely explanation for the observed EGT and CHT behaviors was that the number 3 cylinder fuel injector was being intermittently blocked. As the fuel mixture leaned due to the blockage, it produced the spikes observed in EGT, and the blockage eventually progressed to a point where the cylinder was no longer producing power, resulting in the observed gradual CHT cooling. Postaccident examination of the number 3 cylinder fuel injector showed that it was absent of debris and deposits; therefore, the nature and origin of the blockage could not be definitively determined.

Text from the NTSB. Open the NTSB docket for ERA20LA290 for the full record.