Anchorage, AK, USA
N7640D
Piper PA-22-150
The pilot reported that while in level cruise flight he noticed the smell of burning oil, which was immediately followed by a change in engine sound, followed by a partial loss of engine power. The engine continued to lose power and the pilot selected a snow-covered beach as a forced landing site. During touchdown, as the airplane's main landing gear wheels contacted an area of deep snow, it abruptly nosed over, sustaining substantial damage to the wings, fuselage, and empennage. Examination of the engine revealed that there was no engine oil in the sump. An oil cooler B-nut, which was located on the right side of the oil cooler, was found loose, and there was a significant oil streaking on the right side of the fuselage. Review of maintenance records revealed that there had been no recent maintenance activity to the oil cooler or other engine components adjacent to the loose B-nut. Given the accident pilot’s account of the accident, along with the discovery of the loose oil cooler B-nut, it is likely that the engine failed due to oil starvation after all engine oil was lost through the loose B-nut.
On January 22, 2019, about 0915 Alaska standard time, a Piper PA-22-150 airplane, N7640D, sustained substantial damage when it was involved in an accident near Anchorage, Alaska. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that while in level cruise flight over the tidal waters of the Cook Inlet, he noticed the smell of burning oil, which was immediately followed by a change in engine sound. He turned the airplane 180° to return to the southern shoreline of the Cook Inlet, and as the airplane approached the shoreline, the engine began to run rough and lose power. As the airplane passed over the shoreline, the engine continued to lose power and the pilot selected a snow-covered beach as a forced landing site. During touchdown, as the airplane's main landing gear wheels contacted an area of deep snow, it abruptly nosed over, sustaining substantial damage to the wings, fuselage, and empennage. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed a loose oil cooler B-nut located on the right side of the oil cooler. The FAA inspector also reported that there was significant oil streaking on the right side of the fuselage extending from the engine cowling to the empennage. The engine dipstick revealed no engine oil in the sump. A review of the accident airplane’s maintenance records revealed that there was no recent maintenance activity to the oil cooler or other engine components adjacent to the loose B-nut. In a follow-up conversation with the FAA inspector, the pilot noted that during his preflight, just before the accident flight, there were no oil leaks found, and that he routinely checked around the oil cooler during every preflight.
A loss of engine power due to oil starvation as the result of a loose B-nut fitting on the engine oil cooler, resulting in a forced landing to a soft, snow-covered surface, and a subsequent nose over.
Source: NTSB Aviation Accident Database
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