N4486L

On May 31, 2024, about 1909 central daylight time, a Temco/Lazier TT-1 airplane, N4486L, was substantially damaged when it was involved in an accident near Laurel Hill, Florida. The commercial pilot and one passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 positioning flight.

The purpose of the flight was to reposition the vintage jet trainer airplane from Tuscaloosa National Airport (TCL), Tuscaloosa, Alabama, to Bob Sikes Airport (CEW), Crestview, Florida. The pilot reported that he departed from TCL at 1826 with the fuel tanks “topped off” at 224 gallons. After 33 minutes at a cruise altitude of 12,500 ft, he began the descent to CEW. At 1905, the “FUEL PRESSURE LOW” annunciator illuminated in the cockpit. He stated that he immediately verified the electric fuel boost pump was On and the switches for fuel transfer from the tip tanks to the main tanks were both in the On position. The engine flamed out and he attempted unsuccessfully the restart procedures several times. Unable to glide the airplane to CEW, the pilot performed a forced landing to a nearby field with the landing gear retracted and full flaps lowered. The airplane touched down and was damaged after landing on uneven terrain and contacting a barbed-wire fence.

Postaccident examination revealed substantial damage to the aft fuselage and that the empennage had separated consistent with impact. The outboard sections of both wings were buckled downward, with the wingtip fuel tanks still attached. The forward fuselage and wings were intact except for scraping damage to the lower fuselage. The left tip tank had a tear in the outer aluminum skin but the interior bladder was undamaged.

The airplane was equipped with 50-gallon tip tanks on each wing and three bladder tanks inside each wing, with a total capacity of 62 gallons per wing. The total fuel capacity for the airplane, including the tip tanks, was 224 gallons. Wreckage recovery personnel reported that there were about 33 gallons of fuel were recovered from the left tip tank, and about 40 gallons were recovered from the right tip tank. About 30 gallons in total were recovered from the two inboard wing tanks (the four outboard wing tanks were empty). In total, about 103 gallons total were recovered from the entire fuel system. The amounts of fuel were estimates only and were not exactly measured.

The airplane was equipped with 50-gallon tip tanks on each wing, and three bladder tanks inside each wing with a total capacity, per wing, of 62 gallons

A fuel transfer pump was fitted to the lower side of each tip tank. By design, fuel was transferred to the main wing tanks using the transfer pumps, operated by electrical switches in the cockpit, installed in the tip tanks. Both tip tank pump switches were found in the On position after the accident. A guidance document found in the airplane after the accident advised pilots to burn 60 gallons from the main tanks before turning the transfer pumps on. There were no fuel quantity indicators installed for the main tanks, so fuel burn had to be estimated based on power demand. According to the operator, the pumps would continue to operate after engine flameout if battery power was available.

The postaccident examination of the engine revealed no evidence of case rupture or fluid leakage. During the examination, the pumps were energized with a battery source, and they operated normally. The fuel quantity transducers were removed, and they were tested and found to operate normally. The engine was twice rotated using the battery-powered starter, each time for about 10 seconds; the spool-up sounded normal with no unusual engine noises were noted.

The airplane was equipped with a Shadin Avionics fuel flow indicator, which was removed from the instrument panel and sent to the NTSB Vehicle Recorders Laboratory for examination and download of its nonvolatile memory. The data revealed that 144 gallons of fuel had been used, and 81.4 gallons of fuel remained at engine power-off.

According to the operator, the transfer rate from both tip tanks was about 80 gallons per hour total, or 1.33 gallons per minute. According to recorded fuel flow data, the average fuel burn for the accident flight was about 222 gallons per hour.