WPR11LA374

A partial loss of engine power immediately after takeoff for undetermined reasons.

The day before the accident, the pilot flew himself and his family to an airport about 275 miles away for the purpose of positioning the airplane for filming. The airplane was flown by another pilot during that filming, which was accomplished on the day of the accident. After the filming, the airplane was fueled, and the pilot and his family departed on their return trip. En route to the destination, the pilot diverted to another airport because one of the children did not feel well. They spent about 20 minutes at that airport, and then re-boarded the airplane to complete the trip. Engine start, runup, and the takeoff roll were normal, but when the airplane was about 100 feet above ground level, the engine began to lose power. The pilot pushed the nose down to maintain his target airspeed, but the airplane continued to decelerate. The pilot then landed straight ahead in a plowed field off the end of the runway. Initial examination of the airplane and engine did not reveal any preimpact discrepancies that would have precluded continued flight. Normal procedures call for the takeoff to be conducted with the electric fuel boost pumps operating and then switched off during the climb. The pilot reported that the boost pump switch was on for takeoff and that he did not turn it off before the engine power loss. Postaccident engine test runs revealed that the engine would not run at high rpm without the boost pumps operating. Further examination and testing revealed that a fuel check valve, designed to ensure sufficient fuel flow to the carburetor when the fuel boost pumps were not operating, did not function properly due to a deteriorated gasket. As a result, fuel from the engine driven pump could be pumped back into the fuel tanks instead of into the carburetor. Although the engine test runs demonstrated that, due to the failed check valve, the engine would not run at high rpm without the electric boost pumps, the investigation was unable to determine why the deteriorated check valve did not manifest itself on previous flights. Because the pilot reported that he did not turn off the boost pumps on the accident flight, the defective check valve likely did not cause the loss of engine power. A chart for carburetor icing potential indicated that conditions were conducive to icing at glide and cruise power. Even if the airplane had developed carburetor ice on the approach, it is likely that the 20 minutes spent on the ground, at an ambient air temperature of 33 degrees, would have melted that ice. The fact that the power loss occurred with the engine at takeoff power suggested that while takeoff carburetor ice might have been possible, it was not likely. The temporary nature of carburetor ice, combined with the fact that the airplane was not examined in detail immediately subsequent to the accident, precluded the investigation from determining whether carburetor icing was present at the time of the power loss. Finally, because the fuel quantities in the low-wing airplane were relatively low, the resultant head pressure in the fuel lines would be low. This, in combination with the hot engine and the 20-minute ground time on a hot ramp at an airport with an ambient temperature of 33 degrees C, could have precipitated partial or full vapor lock in the fuel system, which did not manifest itself until the takeoff demanded full power and maximum fuel flow. The investigation was not able to determine whether the source of the power loss was fuel system vapor lock or carburetor ice.

HISTORY OF FLIGHT On August 6, 2011, about 1906 Pacific daylight time, a SIAI Marchetti F.260, N408FD, was substantially damaged during an off-field forced landing immediately after takeoff from Harris Ranch Airport (3O8), Coalinga, California. The airline transport pilot and the three passengers received minor injuries. The business flight was operated under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The airplane was operated by Attitude Aviation, based at Livermore Airport (LVK), Livermore, CA. According to the pilot, he, his wife, and their two daughters flew in the airplane from LVK to Van Nuys Airport (VNY) Van Nuys, CA the day prior to the accident, for the purpose of positioning the airplane for filming. The airplane was flown by another pilot during that filming, which was accomplished on the day of the accident. Once the filming was completed, the airplane was fueled, and the pilot and his family departed VNY for LVK. En route to LVK, the pilot diverted to 3O8 because one of his daughters did not feel well. They spent about 20 minutes at 3O8, and then re-boarded the airplane for the leg to LVK. No fuel was uploaded to the airplane at 3O8. The pilot stated that engine start, runup, and the takeoff roll on runway 14 were normal. When the airplane was about 100 feet above ground level, the pilot selected the landing gear to the 'up' position, and about the same time, he noticed that the engine seemed to lose power. He pushed the nose down to maintain a target airspeed of 100 knots, but the airplane continued to decelerate. He then selected the landing gear to the 'down' position, and decided to land straight ahead off-airport, since he did not believe that the airplane was capable of continued flight. The airplane came to rest upright, about 600 feet beyond the departure end of the runway. PERSONNEL INFORMATION According to Federal Aviation Administration (FAA) records, the pilot also held a flight instructor certificate, with ratings for single- and multi-engine airplane, and instrument airplane. His most recent FAA first-class medical certificate was issued in January 2011. The pilot reported a total flight experience of 5,900 hours, including 200 hours in the accident airplane make and model. AIRCRAFT INFORMATION According to FAA information, the airplane was manufactured in 1973, and was equipped with a Lycoming O-540 series engine. The airplane was equipped with four separate fuel tanks, with a total capacity of 62 gallons. The engine was equipped with an engine-driven fuel pump. The fuel system design and as-found configuration incorporated two electric boost pumps plumbed in parallel with one another, and in series with (prior to) the engine driven pump. The two electric boost pumps were activated by a single cockpit switch. A check valve was installed in the engine compartment, between the pressure side of the fuel boost pumps and the engine-driven fuel pump. The purpose of this valve was to prevent the fuel from the engine-driven pump from returning to the fuel tank(s), instead of being supplied to the carburetor, when the boost pumps are not operating. A review of the maintenance records indicated that the engine was overhauled in 1990, when it had accumulated about 640 hours in service. No significant problems with the fuel system were documented. As of the most recent annual inspection in April 2011, the airplane and engine had accumulated a total time in service of about 1,756 hours. METEOROLOGICAL INFORMATION The 1856 automated weather observation at an airport 15 miles east of 3O8 included winds from 360 degrees at 7 knots, temperature 33 degrees C, dew point 14 degrees C, and an altimeter setting of 29.83 inches of mercury. When the intersection of the ambient air temperature and dew point values was located on a chart that depicted carburetor ice envelopes, the point was in the envelope labeled "Icing at Glide and Cruise Power." AIRPORT INFORMATION FAA information indicated that the 3O8 runway measured 30 feet wide by 2,820 feet long, with an elevation of 470 feet. WRECKAGE AND IMPACT INFORMATION After the accident, the airplane was essentially intact, with the exception of the landing gear, propeller, lower cowl, and portions of the wings and tip tanks. The airplane and engine were not examined in detail on scene. On-scent post-accident photographs indicated that the fuel selector valve was set to the left main tank. All four fuel tank caps were properly installed, and only the left tip tank had been breached by impact. According to recovery personnel, the following approximate quantities of fuel were observed in the four tanks: Left tip 0 gallons (empty); Left main 12 gallons; Right main 4 gallons; Right tip 3 gallons. Some fuel was present in the gascolator, and water detection paste did not indicate the presence of water in that fuel. About 7 fluid ounces of fuel were recovered from the carburetor. A detailed examination of the airframe and engine was conducted after the airplane had been partially disassembled (wings removed) and transported to a secure facility. Examination of the airframe did not reveal any pre-accident conditions or failures that could have contributed to the loss of engine power. The overall appearance of the engine was clean and consistent with normal use and operation; no visual abnormalities were observed. With the exception of the carburetor heat cable and door, all engine cables, lines, and wires were intact and undisturbed. The magnetos and all other accessories were securely mounted to the engine. The dipstick indicated that the engine contained 9 quarts of oil. The interior surfaces of the two exhaust pipes were nearly white; the coating was thin and did not wipe off easily by hand. All 6 top spark plugs were removed; all electrodes were clean and gray-white in color, and the engine was rotated easily by hand. Thumb compressions and valve train motion was verified on all cylinders. ADDITIONAL INFORMATION Engine Run Based on the engine condition and observations, it was decided to test run the engine on the airframe. The damaged carburetor air box was removed, and the top spark plugs were reinstalled. The damaged propeller was removed and replaced with an undamaged propeller. A temporary fuel container, located about mid-fuselage height, was plumbed into one of the airplane fuel lines on the left side. An engine start using the airplane's battery and checklist was attempted; the engine rotated slightly but then stopped due to apparent lack of battery power. An auxiliary power supply was connected to the battery, and the engine started successfully. Engine instrument indications appeared normal; the engine smoothed out after about 20 seconds, and idled normally at about 1,000 rpm. The throttle was advanced to about 1,400 rpm, and shortly thereafter the engine stumbled and then stopped running. Total run time was estimated to be about 90 to 120 seconds. No specific reasons for the stoppage were determined. A re-check of the fuel pressure with the electric boost pump switch on suggested that the pumps were not getting fuel, since a different pump sound was produced before and after the run, and 0 psi was observed on the fuel pressure gauge. The fuel shutoff cock and the fuel selector valve were cycled and returned to their normal positions while the electric boost pump switch was on, until the pump noise changed, and the fuel pressure rose to and stabilized at a pressure of about 6 psi. The engine was re-started, and was run successfully to about 1,900 rpm, with a manifold pressure of about 29 inches of mercury. A magneto check indicated that the engine ran well on either magneto. With the engine operating between 1,500 and 1,900 rpm, switching off the electric boost pump switch resulted in an immediate decrease in