ANC18LA002

During a prebuy inspection flight, the airline transport pilot reduced engine power to test the airplane's slow-speed handling characteristics. He then increased the throttle to restore full engine power, but the engine seemed to "bog down" and lose power. He then lowered the airplane's nose, and engine power was restored. The pilot then chose to return to the airport, and while on approach, the engine again began to lose power, but lowering the airplane's nose did not increase the rpm this time. The pilot realized the airplane would be unable to reach the airport, so he conducted an off-airport landing in a residential area, during which the airplane impacted a fence. A postaccident engine run revealed that, after running at various power settings, when the power was reduced, the engine bogged down and backfired through the power takeoff (PTO) carburetor, and the rpm would not increase. The PTO cylinder ignition coil was replaced with a serviceable coil, and the engine was restarted for several minutes and run through various power setting. The engine accelerated normally without backfiring, hesitating, or stumbling. It is likely that, during the accident flight, the PTO cylinder ignition coil broke down, which resulted in an intermittent spark at the PTO spark plug and a partial loss of engine power.

On October 11, 2017 about 0900 central daylight time, an experimental amateur-built, Fleetwood Jack, Team Air-Bike airplane, N7566D sustained substantial damage during a forced landing, following a partial loss of engine power while attempting to return to Ocean Springs Airport (5R2), Ocean Springs, Mississippi. The airplane was registered to a private individual and operated by the pilot, as a visual flight rules flight under the provisions of 14 Code of Federal Regulations Part 91 when the accident occurred. The certificated airline transport pilot was not injured. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot reported that he was contemplating purchasing the airplane, and the flight was a part of the pre-buy inspection. He stated that during the test flight, he reduced the power to test the slow speed handling characteristics of the airplane. Following slow flight, he increased the throttle, but the engine seemed to "bog down". In an attempt to increase the engine's RPM, he lowered the nose of the airplane and the engine seemed to respond and run normal again. He stated that he was uncomfortable with the way the engine was operating and decided to return to 5R2. During the approach to runway 36 at 5R2, the airplane seemed to "bog down" again. He lowered the airplane's nose, but the engine failed to increase in RPM. Realizing he would be unable to reach the airport, he selected an off-airport landing site in a residential area. During the forced landing the airplane impacted a fence and sustained substantial damage to the fuselage and wings. According to FAA records, the airplane was manufactured in 2005. It was an experimental single place, externally braced high wing airplane, with a two-blade fixed wood propeller, and a Rotax 503, 50 hp, two-stroke engine. A postaccident examination of the airplane and engine revealed that the wings and fuel tank had been removed, and were not available for examination. The Rotax 503 engine remained attached to the airframe, and both propeller blades had separated from the propeller hub. The fuel system was inspected; no fuel filter was present between the fuel pump and carburetor as required per the ROTAX Aircraft Engines Installation Manual for ROTAX 503 UL DCDI engines. However, a fuel filter was present upstream of the fuel pump on the fuel inlet line. The filter appeared clean, with no debris present. The fuel pump had been previously removed and disassembled, and was not an appropriate type for an aircraft application. The airplane was equipped with an aftermarket type exhaust, and an exhaust leak was noted at one of the welds. The exhaust was removed from the engine, and a continuity and compression check was completed via manual rotation of the propeller. No anomalies were noted on the power take off side (PTO) and magneto side (MS) pistons and cylinders, as viewed from the exhaust port. The PTO and MS spark plugs were removed from the engine and both plugsexhibited features consistent with a rich mixture, and were not designed for use in aircraft. The PTO spark plug was broken. The engine was then prepped to be test run, which included replacing the propeller, mounting a serviceable fuel pump and replacing the damaged spark plug. Fuel was introduced to the engine by placing the fuel inlet line in a fuel container with the appropriate fresh fuel/oil mixture. The engine was started and run for several minutes at various power settings. The power was then reduced, prior to applying full power. The engine bogged down and backfired through the PTO carburetor and would not increase in RPM. The PTO ignition coil was replaced with a serviceable coil, and the engine was restarted for several minutes and run through various power settings. The power was then reduced, prior to the throttle being opened. The engine accelerated normally without backfiring, hesitation or stumbling. According to an FAA inspector, the accident airplane, as equipped, did not meet the requirements contained in 14 CFR Part 103 to be considered an Ultralight Vehicle. The closest weather reporting facility was Keesler Air Force Base, Biloxi, Mississippi, about 10 miles west of the accident site. At 0856, a METAR was reporting, in part: wind 010° at 5 knots; visibility, 10 statute miles; clouds and ceiling, clear; temperature, 79° F; dew point 75° F; altimeter, 30.06 inches of Mercury.