Wasilla, AK, USA
N7440P
PIPER PA-24-250
The private pilot was on a Title 14, CFR Part 91, local area personal flight when the accident occurred. As he approached his destination airport he applied full carburetor heat, which resulted in a loss of engine power. After completing emergency engine procedures he was unable to restore engine power, and selected a shallow lake as a forced landing site. The airplane sustained substantial damage to the fuselage during the forced landing. The pilot reported that while the airplane was being disassembled after recovery, his mechanic removed the lower engine cowling, and discovered a worn, 4 inch by 2 inch portion of rubberized baffling material lodged inside of the carburetor air box assembly. An NTSB investigator traced the origin of the baffling to a worn, frayed, and torn section of engine cowling baffling adjacent to the carburetor heat fresh air inlet duct. The pilot/owner of the airplane reported that he was aware of the worn, frayed and torn engine baffling, and he planned to have it replaced at the airplane’s next annual inspection. Given the discovery of the baffling material inside the carburetor air box, it is likely that once carburetor heat was applied, airflow pulled the baffling material into the carburetor inlet, restricting airflow to the carburetor with the resultant loss of power.
On May 16, 2009, about 1140 Alaska daylight time, a Piper PA-24-250 airplane, N7440P, sustained substantial damage during a forced landing and ditching in Lake Lucille, Wasilla, Alaska, following a loss of engine power. The solo private pilot was not injured. The airplane was being operated as a visual flight rules personal flight under Title 14 Code of Federal Regulations Part 91 when the accident occurred. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The flight originated at the Anderson Lake Airport, Wasilla, about 1040. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on May 16, the pilot said that after departing the Anderson Lake Airport, he flew southeast over the Knik Glacier. He said that before returning to the Anderson Lake Airport he did a touch-and-go landing at the Wasilla Airport. After the touch-and-go landing, he climbed the airplane to 1,700 feet msl and flew east toward the Anderson Lake Airport. The pilot reported that while in cruise level flight, he applied full carburetor heat, and all engine power was lost. After completing the emergency procedures for a loss of engine power, he was unable to restart the engine. The pilot said he initially selected a portion of the Parks Highway, a four-lane highway, as an emergency landing site, but vehicle and pedestrian traffic would not allow for a safe landing. He then selected Lake Lucille for a forced landing, which is next to the Parks Highway. The pilot said that he did not lower the airplane’s landing gear, and he selected full flaps during the emergency descent to the lake. He said he ditched the airplane about 100 feet from the north shoreline of the lake. After ditching, the pilot indicated that the airplane initially floated. He said that just before the airplane sank, a small pontoon boat arrived, and took him to shore. The airplane sustained substantial damage to the fuselage during the ditching. The airplane was equipped with a Lycoming O-540-A1D5 engine. An FAA airworthiness inspector from the Anchorage Flight Standards District Office (FSDO), traveled to the accident site on May 19 and examined the wreckage. No preaccident mechanical anomalies were discovered during the examination. During a telephone conversation with the NTSB IIC on May 20, the pilot/owner of the airplane reported that as his mechanic was disassembling the airplane during recovery efforts, he removed the lower engine cowling, and discovered a 4 inch by 2 inch portion of rubberized baffling material lodged inside of the carburetor air box assembly. On May 20, an NTSB investigator traveled to the accident site to document the mechanic’s findings. The NTSB investigator traced the origin of the baffling to a worn and frayed section of engine cowling baffling that was adjacent to the carburetor heat fresh air inlet duct. During a follow up conversation on May 20, the pilot/owner of the airplane reported that he was aware of the worn, frayed and torn engine baffling and he planned to have it replaced in the near future, or at the airplane’s next annual inspection. The closest official weather observation station is at the Wasilla Airport. At 1156, an Aviation Routine Weather Report (METAR) was reporting, in part: Wind, calm; visibility, 10 statute miles; clouds and sky condition, 4,900 feet few, 9,000 feet scattered; temperature, 54 degrees F; dew point, 36 degrees F; altimeter, 30.01 inHg. .
A loss of engine power due to the blockage of the carburetor air inlet by a piece of engine baffling. Contributing to the accident was a worn engine baffle, and the pilot/owner's failure to have the engine baffle replaced.
Source: NTSB Aviation Accident Database
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