NORFOLK, VA, USA
N43GP
Siai-Marchetti SF260TP
The airplane departed with 40 gallons of fuel on board, flew locally for about 30 minutes, then returned to the airport to land. While in the traffic pattern, the low fuel pressure warning light illuminated several times. During final approach, the light remained illuminated, and the pilot switched the fuel selector from the "NORMAL" position to the "EMERGENCY" position. The engine experienced several compressor surges and then lost power. The pilot flared high to get over a seawall, and impacted the ground about 900 feet short of the runway. Visual examination of the fuel tanks revealed 10 gallons in the right fuel tank, 5 gallons in the left (main) fuel tank, and about 3 gallons in each tip tank. A review of the airplane's fuel distribution system revealed that fuel was delivered to the engine from the left fuel tank, which was fed by the tip tanks and right tank through the transfer pump. An operational check of the airplane's fuel system revealed little to no fuel flow when the fuel selector was placed in the "NORMAL" position. No fuel flow was observed when the fuel selector was selected to the "EMERGENCY" position. During the check, the transfer pump was manually tapped, and then a steady fuel flow stream was observed. The fuel transfer pump motor cover was removed and carbon deposits, dirty internal windings, and evidence of corrosion was observed. Examination of the airplane and engine revealed no pre-impact malfunctions.
On June 9, 2000, about 1851 Eastern Daylight Time, an experimental certificated Siai-Marchetti SF260TP, N43GP, was substantially damaged after it experienced a loss of engine power while landing at the Norfolk International Airport (ORF), Norfolk, Virginia. The certificated commercial pilot/owner received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91. The pilot stated that prior to being refueled, 14 gallons of fuel was contained in the airplane's fuel tanks. The airplane was then refueled with 25 gallons of Jet-A fuel. At departure, both wing tanks were full and the wing tip tanks held about 7 gallons in each tank. The pilot flew locally for about 30 minutes, and then returned to the airport to perform a full-stop landing on Runway 23. On the downwind leg of the traffic pattern, the pilot reduced the power and noticed what he thought was a "compressor surge." He set the power at 20% N1, extended 25 degrees of flaps, and turned onto the base leg of the traffic pattern. The pilot noticed the low fuel pressure warning light illuminate for several seconds and then go out. He then turned onto the final approach leg of the traffic pattern, and observed the low-pressure warning light illuminate a second time, and then it went out again. The pilot assured the fuel selector was in the "normal" position and confirmed the position of all switches and circuit breakers were "normal." The low fuel pressure light came on a third time, and remained illuminated for the duration of the flight. The pilot then switched the fuel selector from the "normal" to the "emergency" position. After several seconds, the pilot noticed "three or four discernable compressor surges and the engine flamed out." The time duration between the first surge to the flameout was about 10 seconds. At the time of the flameout, the pilot observed an altimeter indication of 600 feet. He then retracted the flaps and slowed the airplane to 90 knots. He attempted to restart the engine twice, with the fuel selector set on "emergency" for at least the first attempt. At 150 feet above the ground, the pilot extended the landing gear and then the flaps. He flared about 30 feet above the ground to climb over a "seawall," and the airplane impacted the ground at or close to a "fully stalled condition." The airplane bounced back into the air and when it came back down, the left wing hit the ground first, followed by the nose. The airplane came to rest upright, about 900 feet short of the runway. The pilot turned off all switches, moved the fuel selector to "off," and exited the airplane. WRECKAGE AND IMPACT INFORMATION The airplane was examined at ORF under the supervision of a Federal Aviation Administration (FAA) inspector. It was noted that both wings and the landing gear were substantially damaged. The propeller and the front portion of the propeller gearbox were separated from the engine during the impact sequence and came to rest near the airplane. All four fuel tanks were not breached and did not reveal any damage. The fuel filler caps were removed and 3 to 4 gallons of fuel was observed in each tip tank. The right fuel tank contained about 10 gallons, and visual examination of the left fuel tank indicated the fuel was below the fuel level transmitter switch, about 5 gallons. Examination of the fuel filter revealed it was clean; however, light residual sediment was found in the filter bowl. No abnormalities were found in the fuel feed line in the left tank, and no obstructions were observed in the fuel vents. An operational fuel check was performed on the airplane. The fuel inlet line to the engine driven fuel pump was disconnected and battery power was supplied to the airplane. The fuel selector was placed in the "normal" position and fuel flow to the engine driven fuel pump was noted as "erratic," or little to no fuel flow. The fuel selector was then selected to the "emergency" position and no fuel flow was observed. The airplane owner then tapped on the airplane panel where the transfer pump was located and a steady fuel flow stream was observed. The FAA inspector added fuel (about 5 to 6 gallons) to the left fuel tank. The fuel selector was moved to the "normal" position, and a steady stream of fuel flow was observed. Fuel in the left tank was then drained to test the activation of the transfer pump. As the fuel decreased from the full tank, the transfer pump required being tapped to activate. The fuel transfer pump motor cover was removed and carbon deposits, dirty internal windings, and evidence of corrosion was observed. Examination of the engine revealed that the compressor and turbine sections turned freely, and exhibited no visual damage. The propeller gearbox was detached from the engine where it connected to the accessory gearbox. Examination of the engine driven fuel pump revealed no mechanical malfunction; its filter and drive shaft were removed and displayed no abnormalities. The fuel line to the fuel nozzle was disconnected at the fuel nozzle and no evidence of fuel was observed in the line. The engine was removed from the airplane and sent to the manufacturer for further examination. TESTS AND RESEARCH The engine was examined at Rolls-Royce, on August 2, 2000, under the supervision of the FAA. The examination revealed the propeller drive case was broken aft of the forward flange. The engine output to the propeller gear train was damaged, and the planetary gears exhibited impact damage. The gear train in the accessory gearbox and the planetary gears in the propeller gearbox turned freely. Examination of the magnetic chip detectors in the accessory gearbox and the propeller gear case revealed no contamination, other than light fuzz. The engine driven fuel pump was removed, and continuity of the drive gear was confirmed. The fuel lines, which connected to the fuel flow transducer, were disconnected and no obstructions were observed. A continuous continuity check was performed, which revealed the compressor and turbine sections turned freely without rubbing sounds. Due to severe damage to the Power Takeoff (PTO) gear shaft, the engine could not be functionally tested. The fuel control unit, the propeller governor, and the overspeed propeller governor were removed from the engine and sent to their respective manufacturers for further examination. The propeller governor and the overspeed governor were tested at the Woodward Governor Company, under the supervision of the FAA. No pre-impact malfunctions were observed. The fuel control unit was tested at Honeywell South Bend, under the supervision of the FAA. No pre-impact malfunctions were observed. The transfer pump was tested by a Safety Board investigator; however, it was noted that the pilot/owner disassembled the pump and performed his own testing, before sending it to the Safety Board. Examination by the Safety Board investigator did revealed any abnormalities with the operation of the pump or the motor. ADDITIONAL INFORMATION According to the pilot's flight manual, the airplane was equipped with two wingtip fuel tanks and two main fuel tanks, one on each wing. Each tip tank had a capacity of 18.3 gallons of useable fuel, and each main tank had a capacity of 10.75 gallons of useable fuel. The fuel distribution system consisted of the fuel supply system and the fuel transfer system. The fuel supply system supplied fuel to the engine from the left main wing tank. The fuel transfer system provided automatic fuel transfer from the tips and right main tank to the left main tank. When the fuel selector was set to the "NORM" position, fuel was transferred automatically from the tip tanks to the left main tank, when the fuel quantity in the tank descended below 10 gallons (38-40 liters). The transfer pump supplied fuel into the main tank until the raising fuel level opened the high fuel level switch and de-energized the transfer pump (about 11 gallons). When the fuel quantity in the tip tanks descended below .66 gallons (2.5 liters), the low fuel level switch in the tip tanks de-energized to close the left and right tip fuel shut-off valves and opened the right wing fuel shut-off valve. The fuel transfer pump then transferred fuel from the right main tank. The left and right tip fuel transfer time relay was rated at a 20 second time delay to prevent the cycling of fuel transfer due to fuel sloshing in the tip tanks. When the fuel selector was set in the "EMERGENCY" position, fuel was delivered directly to the engine from the right tank. In this position, the fuel selector valve connected the transfer line directly to the supply line, and the selector lever mechanically operated the tip tank cut-off and transfer pump emergency power switches. Operation of these switches closed the left and right fuel shut-off valves and energized the transfer pump, which drew fuel from the right wing tank and supply it directly to the engine. The manual stated that when the fuel selector was set in the "EMERGENCY" position, a flame out may be expected due to a possible emptied line from the transfer pump to the fuel selector. Additionally, the manual stated, ".. Engine stoppage is generally due to improper or defective fuel supply system operation. This condition is indicated by the illumination of the "LOW FUEL PRESS" warning light." According to the FAA, the transfer pump did not require any scheduled servicing. Examination of the airplane logbooks revealed no entries for maintenance performed on the transfer pump.
Fuel starvation of the engine, caused by the failure of the fuel transfer pump.
Source: NTSB Aviation Accident Database
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