Inspection Following Accident Found Loose Nut Between Fuel Sensor And Fuel Pump

Sometimes even when you think you've done everything right ... something can go seriously wrong. And such may have been the case in an accident involving a Super Glasair TT which made an off-airport forced landing earlier this month.

According to the NTSB's preliminary report, on June 8, 2014, about 1630 Pacific daylight time, an experimental amateur-built Super Glasair TT, N400MC, was substantially damaged during an off-airport forced landing near Madera, CA. The owner-pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the flight.

According to the pilot, he was enroute from McClellan-Palomar airport, Carlsbad, California (KCRQ) to Reno/Stead airport (KRTS), Reno, Nevada in order to provide training to pilots participating in the upcoming Reno Air Races. He was cruising at an altitude of 10,500 feet, and was not in communication with air traffic control. The airplane has a single 60 gallon capacity fuel tank, and was equipped with two separate means to determine fuel quantity; a capacitance-type quantity gauging system, and a totalizer system that subtracts fuel used from initial fuel quantity.

Shortly before the event, the pilot noted that the totalizer indicated a remaining quantity of 38 gallons, and a fuel burn rate of 15 gallons per hour, which indicated that he had sufficient fuel for the remainder of the flight. Until the event, all systems and operations were normal. At some point during cruise, in rapid succession, the pilot noticed a fuel smell, and the engine lost power, although it continued to windmill. The totalizer indicated that 37 gallons remained, but the capacitance system indicated that the fuel tank was empty. The engine was a Lycoming TIO-580 series.

The pilot initially turned towards Fresno, with the intent to land at an airport there, but then opted to land off airport on a road instead. He observed a road that was long and straight, and appeared to be free of powerlines and other obstructions, and set up for landing on that road. However, after the pilot had deployed the landing gear and was "committed" to that landing selection, he noticed that there was more traffic than he was comfortable with, and therefore opted to land on the verge of the road. Since the verge was unpaved, the landing gear separated from the airplane after touchdown. The right wing struck the vegetation and a wire fence that bounded the verge, and the airplane came to a stop off the right side of the road.

Shortly after the accident, FAA personnel and the pilot decowled the airplane. They observed that a steel B-nut on the line between the fuel pump and the fuel flow sensor had come loose, which allowed all the fuel to be pumped overboard. The B-nut had torque stripe on it but no provisions to be safetied, and the B-nut had backed off.

The pilot, who was also the builder, reported that he conducted the bulk of the maintenance on his airplane. He held an air transport pilot certificate, and was a current airline pilot and former military pilot. He had about 750 hours in the accident airplane make and model.

The 1453 automated weather observation at Madera Municipal airport (KMAE), Madera, California, located about 10 miles west-northwest of the accident site, included winds from 290 degrees at 7 knots, visibility 10 miles, clear skies, temperature 38 degrees C, dew point 7 degrees C, and an altimeter setting of 29.69 inches of mercury.

FMI: www.ntsb.gov