ERA24LA235 · Temco/Lazier TT-1

The pilot of the vintage jet trainer airplane reported that he departed on a cross-country positioning flight with a reported full fuel load of 224 gallons. After uneventful ground operations, takeoff, and departure, he climbed to a cruise altitude of 12,500 ft. About 33 minutes into the flight, he began his descent to the destination airport. About 6 minutes after he began his descent, the pilot observed the “FUEL PRESSURE LOW” annunciator illuminate 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 subsequently flamed out, and his attempts to restart it were unsuccessful. Unable to glide to his destination, the pilot performed a forced landing in a field. The airplane contacted a barbed wire fence and uneven terrain during the landing, resulting in substantial damage to the airframe.

Examination of the engine after the accident revealed no evidence of case rupture or fluid leakage. The engine was twice rotated using the battery-powered starter, for about 10 seconds; the spool-up sounded normal, and no unusual engine noises were noted. About 33 gallons of fuel was found in the left tip tank and about 40 gallons in the right tip tank, although some fuel leakage was possible after ground impact. About 30 gallons of fuel was recovered from the main tanks after the accident.

The airplane’s fuel system was designed such that fuel transferred from the tip tanks to the main fuel tanks in the wings. The examination also revealed that the fuel transfer switches in the cockpit were found in the On positions. Pilots were advised to burn 60 gallons from the main tanks before turning the transfer pumps on. However, there were no fuel quantity indicators installed for the main tanks, so fuel burn had to be estimated based on power demand. The average fuel burn during the accident flight was estimated to be about 222 gallons per hour based on data recovered from a fuel flow indicator installed in the airplane. Based on the 224 gallons of fuel in the main tanks at the start of the flight, the time spent in flight (including taxi, takeoff, and climb), the airplane’s average fuel burn rate during the flight of 222 gallons per hour, and the 80-gallon-per-hour fuel transfer rate from the tip tanks to the main tanks, the pilot likely delayed turning the fuel transfer switches on after takeoff, which allowed fuel to burn from the main tanks faster than it could be transferred from the tip tanks to the main tanks. The engine then flamed out due to an inadequate supply of fuel in the main tanks. The reason that fuel was found in the main tanks after the accident was because the battery-powered fuel transfer pumps continued to operate after the engine flamed out.

Verbatim NTSB analysis and probable cause from the NTSB dataset