NTSB Factual Report

HISTORY OF FLIGHT

On March 7, 2009, about 1645 eastern standard time, an experimental Grumman TBM-3, N188TD, was destroyed following an in-flight and postlanding fire at Millville Municipal Airport (MIV), Millville, New Jersey. The certificated airline transport pilot/mechanic sustained serious injuries. Visual meteorological conditions prevailed and no flight plan was filed for the local maintenance flight conducted under the provisions of 14 Code of Federal Regulations Part 91.

The pilot was not available for interview due to his injuries. In a written statement, the owner of the airplane explained that the pilot had just completed the installation of an overhauled carburetor. The owner and the pilot/mechanic had performed test runs of the engine and completed carburetor adjustments, with no problems noted. He described multiple engine starts with and without auxiliary fuel pressure applied. During one engine run, the hydraulic components of the airplane were "cycled" with no problems noted.

After completion of the ground tests, the pilot stated he would test full-power application by flying the airplane around the traffic pattern. The owner described the takeoff and climbout from runway 14, and stated that the airplane "appeared" to develop full power. When the airplane was about 600 to 700 feet above ground level, on the crosswind leg of the traffic pattern, "heavy smoke appeared all at once."

The owner stated that he then ran to the hangar for a fire extinguisher, and that by the time he returned, the airplane was rolling out on runway 28, completely engulfed in flames. Seconds after the airplane stopped, the engine fell from the burning airframe. At that time, the owner and other witnesses observed the pilot on the runway, about 400 feet from the airplane. The pilot spoke briefly to the owner, and stated that the airplane was "operating properly until he heard a bang and then there was smoke and flames."

PERSONNEL INFORMATION

According to Federal Aviation Administration (FAA) records, the pilot held an airline transport pilot certificate with ratings for airplane single- and multiengine land. He held 10 type ratings, including one for the accident airplane. Additionally, the pilot held a commercial pilot certificate with ratings for airplane single-engine sea, and helicopter, as well as a flight instructor certificate with ratings for airplane single-engine, multiengine, and instrument airplane. The pilot held a mechanic certificate with ratings for airframe and powerplant. The pilot's most recent FAA second-class medical certificate was issued May 22, 2008. He reported 20,000 total hours of flight experience on that date.

AIRCRAFT INFORMATION

According to FAA records, the airplane was a 1945 Grumman TBM-3. The maintenance records were burned in the postaccident fire, but examination revealed that the airplane had accrued 3,012.1 total flight hours as of the last annual inspection, which was performed on May 19, 2008.

METEOROLOGICAL INFORMATION

At 1654, the weather reported at MIV included clear skies with variable winds from 010 degrees at 4 knots. The temperature was 16 degrees Celsius (C), and the dew point was 9 degrees C.

WRECKAGE AND IMPACT INFORMATION

Examination of photographs revealed that the airplane was consumed by fire between the engine and the tail section. The engine showed significant fire damage, and one of the three propeller blades was consumed down to its root.

The engine was examined in Clayton, Delaware on April 2, 2009. Examination revealed that the fuel pressure indicator line was disconnected from its AN-type fitting at the carburetor. The threads of the fitting appeared undamaged, but were heavily sooted. The B-nut fitting threads at the fuel pressure indicator line also appeared undamaged, but were also heavily sooted and contained debris.

Further examination revealed that the fuel supply, the oil supply, and scavenge lines were consumed by fire, but their associated attachment clamps were installed with remnants of the lines still attached.

The hydraulic supply and return fittings were still installed, but heavily damaged by fire. The supply and return lines were consumed by fire.

The AN-type fitting and the fuel pressure indicator line were retained for further examination.

TESTS AND RESEARCH

On November 17, 2009, the AN-type fitting and the fuel pressure indicator line were examined in the NTSB Materials Laboratory in Washington, DC.

Examination revealed the AN-type fitting was threaded with male threads on both ends. One end was threaded with pipe threads and was still threaded into the carburetor housing when it was removed for shipment to the lab. These threads were properly formed and showed no evidence of damage or debris. The opposite end of the fitting was an AN-type nipple for connection to a fuel line for the fuel pressure transmitter, but was found disconnected from the fuel line.

The threads of the nipple were covered in soot and contained small particles of debris consistent with exposure to a fire environment. The soot and debris were strongly adhered to the threads and required removal by brushing to inspect the condition of the threads. The threads appeared properly formed and undamaged.

The B-nut of the fuel line, which would have been connected to the AN-type nipple, was heavily oxidized on the interior and exterior surfaces, and the threads inside the B-nut contained debris. The metal over braid of the fuel line displayed localized melting consistent with electrical arcing.

NTSB Probable Cause

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