Nondalton, AK, USA
The pilot reported that, while the airplane was in level cruise flight, he heard a loud "pop," followed by a total loss of engine power. He subsequently made a forced landing to an open, tundra-covered site. During the forced landing, the airplane nosed over, which resulted in substantial damage to the wings, fuselage, and empennage. A postaccident examination of the engine revealed a fractured exhaust valve stem on the No. 4 cylinder, which subsequently pulverized the electrodes on both sparks plugs and severely damaged the piston.
On September 5, 2013, about 1300 Alaska daylight time, a wheel-equipped Piper J3L-65 airplane, N38262, sustained substantial damage during a forced landing, following a loss of engine power, near Nondalton, Alaska. The airplane was being operated by the pilot as a visual flight rules (VFR) personal cross-country flight under the provisions of Title 14, CFR Part 91, when the accident occurred. The private pilot and one passenger were not injured. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight departed about 1150, from the Keyes Point Airstrip, a private remote fly-in community about 18 miles southwest of Port Alsworth, Alaska. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on September 11, the pilot stated that the purpose of the flight was to scout for moose to hunt. He said that while in level cruise flight, he heard a loud "pop," which was followed by a total loss of engine power, and he made a forced landing to an open, tundra-covered site. During the forced landing, the airplane nosed over, sustaining substantial damage to the wings, fuselage, and empennage. When the flight failed to arrive back at the Keyes Point Airstrip on the evening of September 5, a concerned family member of the passenger reported the airplane overdue. The flight was officially reported overdue to the Federal Aviation Administration (FAA) at 1238, on September 6. Search personnel from the Civil Air Patrol, Alaska State Troopers, Alaska Air National Guard, along with several volunteers, were dispatched to conduct an extensive search effort. No emergency transmitter locator (ELT) signal was received by search personnel. The accident airplane was equipped with an older generation 121.5 MHz ELT instead of a digital, 406 MHz ELT that instantly transmits a distress signal to search and rescue satellites, thereby alerting rescue personnel within minutes of the location of the crash. As of February 1, 2009, analog, 121.5 MHz ELT's stopped being monitored by search and rescue satellites, and the installation of the 406 MHz has been voluntary. Both types of ELT's can be turned on manually, or automatically, by impact forces. On September 7, about 2151, the airplane's overturned wreckage was located by an Alaska State Trooper search airplane about 10 miles north-northwest of Nondalton, but the two occupants were not found at the accident site. On September 8, about 1200, the two uninjured occupants were located about 3 miles northwest of Nondalton. The airplane was equipped with a Continental Motors C-85 series engine. The airplane owner's insurance company sold the airplane wreckage on an "as is, where is" basis. According to the new owner, a postaccident inspection of the airplane's engine revealed a fractured exhaust valve stem on the number four cylinder, which subsequently pulverized the electrodes on both sparks plugs, and severely damaged the piston. Once the number 4 cylinder was replaced, the engine was started, and it continued to operate without further mechanical anomalies. The fractured valve stem was not made available to the NTSB for examination. After repeated requests, the accident pilot did not submit the required 6120.1 Pilot/Operator Aircraft Accident/Incident Report.
The fracture and subsequent failure of the No. 4 cylinder exhaust valve during cruise flight, which resulted in a total loss of engine power.
Source: NTSB Aviation Accident Database
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