FTW04LA094

Following a loss of engine power in the single engine airplane, the private pilot executed a forced landing while on approach to a private grass airstrip. While entering the downwind leg, the pilot reduced power and the engine began to run "rough." After carburetor heat was applied, the pilot advanced the mixture, and throttle with no effect. The engine began to develop power momentarily, and then, on base leg, the engine power became intermittent. Realizing the he may not make the landing area, the pilot selected an open field adjacent to the runway; however, he observed obstacles in the field and turned back toward the grass strip. Subsequently, the airplane impacted small trees and brush, approximately 300 feet short of the intended landing strip, and came to rest within 10 feet from the initial impact point. A post-crash fire ensued. After the accident, the spark plugs were removed and dark, black carbon coating was observed on the tips of their respective electrodes and the sides of the electrode posts were "grayish" in color. The #4 cylinder exhaust flange was partially separated from the cylinder flange, and one nut was missing. There was visual evidence of heat concentration and thermal distress around the exhaust flange, and there was smoke residue observed on the lower fuselage. The engine was mounted on a test stand, started, and was operated for five minutes, up to 1,700 RPM. With full throttle applied, the engine RPM did not exceed 1,700 RPM. During the test run, fuel was observed to be leaking from the mating surface between the carburetor bowl and carburetor upper plate. The engine was then shut down, and the 4 bolts that retain the carburetor bowl to the upper plate were tightened down approximately 1/4 turn each in an attempt to further compress the gasket and abate the fuel leak. While tightening the bolts, it was noted that the carburetor was sooted and it appeared that the gasket had some degree of thermal distress. The engine was then started again. Magneto checks were performed at 1,800 RPM with 75-100 RPM drops, and then again at 2,100 RPM with 75 RPM drops. The engine operated for approximately 10 minutes at 2,100 RPM. According to carburetor icing probability charts, and the available temperature and dew point at the time of the accident, the airplane could have been susceptible to moderate or severe carburetor icing at glide power settings.

On March 17, 2004, approximately 1600 central standard time, a Piper PA-28-151 single-engine airplane, registered to and operated by a private individual, was substantially damaged during a forced landing following a loss of engine power while landing on a private grass strip near Goldwaite, Texas. The private pilot, who was the sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed and a flight plan was not filed for the Title 14 Code of Federal Regulations Part 91 personal flight. The cross-country flight originated from Rockwall Municipal Airport (F46), Rockwall, Texas, at 1410.

The pilot reported to the FAA inspector, who responded to the accident site, that he was completing a cross-country flight from Rockwall, Texas, to visit his family who lived in proximity to the landing strip. He stated that he passed over his parent's home, then proceeded toward the landing strip. On the left downwind leg, as power was reduced to set up for landing, the engine began to run "rough." The pilot applied carburetor heat, advanced the mixture, and advanced the throttle; however, the engine continued to run rough. For a moment, the engine began to respond, and then as the pilot maneuvered the airplane for the left base leg, engine power became intermittent. Realizing the he may not make the landing area, the pilot selected an open field adjacent to the runway; however, he observed obstacles in the field and turned back toward the grass strip. Subsequently, the airplane impacted small trees and brush, approximately 300 feet short of the intended landing strip, and came to rest within 10 feet from the initial impact point. A post-crash fire ensued, and the pilot used an onboard portable fire extinguisher to extinguish the fire.

Examination of the aircraft by the FAA inspector at the accident site, revealed that the engine cowling and engine mount were destroyed, the lower fuselage was wrinkled from the aft spar forward, the nose landing gear was torn under the fuselage, and the engine firewall was buckled. One propeller blade was bent approximately 80-degrees, and the other blade was straight. The propeller spinner was dented. The left wing was structurally damaged inboard from the fuel tank, and the right wing was structurally damaged. The flaps were in the fully retracted position, and the fuel pump and landing light circuit breakers were "tripped." The fuel selector valve was found on the left tank position. The fuel strainer at the firewall was examined, and the screen was clean. Fuel flowed freely from the right tank when selected without a boost pump; however, fuel did not flow from the left tank when selected. The inspector was unable to power the airplane in order to run the boost pumps, due to burned wiring. The spark plugs were removed and dark, black carbon coating was observed on the tips of their respective electrodes and the sides of the electrode posts were "grayish" in color. The #4 cylinder exhaust flange was partially separated from the cylinder flange, and one nut was missing. There was visual evidence of heat concentration and thermal distress around the exhaust flange, and there was smoke residue observed on the lower fuselage.

On April 21, 2004, the engine was prepared and set in a test stand at Air Salvage of Dallas, Lancaster, Texas. Under the supervision of the NTSB, the engine was started, and was operated for five minutes, up to 1,700 RPM. With full throttle applied, the engine RPM did not exceed 1,700 RPM. During the test run, fuel was observed to be leaking from the mating surface between the carburetor bowl and carburetor upper plate. The engine was then shut down, and the 4 bolts that retain the carburetor bowl to the upper plate were tightened down approximately 1/4 turn each in an attempt to further compress the gasket and abate the fuel leak. While tightening the bolts, it was noted that the carburetor was sooted and it appeared that the gasket had some degree of thermal distress. The engine was then started again. Magneto checks were performed at 1,800 RPM with 75-100 RPM drops, and then again at 2,100 RPM with 75 RPM drops. The engine operated for approximately 10 minutes at 2,100 RPM.

According to carburetor icing probability charts, and the available temperature and dew point at the time of the accident, the airplane could have been susceptible to moderate or severe carburetor icing at glide power settings.