Grumman TBM-3 N188TD accident near Millville, New Jersey

Probable cause

The pilot/mechanic’s failure to properly torque the fuel pressure line B-nut to the carburetor fitting.

NTSB analysis

The owner of the airplane explained that the pilot/mechanic had just completed the installation of an overhauled carburetor, and that he and the pilot/mechanic had performed test runs of the engine and completed carburetor adjustments with no problems noted. The owner described multiple engine starts with and without auxiliary fuel pressure applied and during one engine run the hydraulic components of the airplane were "cycled" with no problems noted. After completion of the ground tests, the airplane appeared to develop full power during takeoff and climbout when "heavy smoke appeared all at once." The airplane landed and was completely engulfed in flames during rollout. Seconds after the airplane stopped, the engine fell from the burning airframe. Examination of the engine revealed that the fuel line associated with the fuel pressure transmitter was found disconnected from its mating fitting on the carburetor. The fitting on the carburetor and the mating nut on the end of the fuel line showed evidence of exposure to a fire environment on the surfaces, which would normally be protected if the two components were assembled. The fitting on the carburetor and the mating nut on the fuel line did not have damaged threads, which would be expected if the components were separated by force.

Text from the NTSB. Open the NTSB docket for ERA09LA191 for the full record.