Poplar Grove, IL, USA
N886MJ
RAND ROBINSON KR2
Shortly after departure, the pilot smelled oily smoke and noted a loss of engine oil pressure and an increase in oil temperature. The engine lost power, and the pilot performed a forced landing to a corn field. During the landing, the nosewheel dug into the field and the airplane nosed over, resulting in substantial damage to the wings and vertical stabilizer. An examination of the engine revealed no mechanical anomalies that would preclude normal operations. The source of the oil leak was not identified. The pilot later reported that, after researching and consulting with other pilots who operated the engine type installed on the accident airplane, he believed that the loss of engine power was the result of vapor lock in the throttle body injection (TBI) system. His research indicated that other airplane owners provide “blast cooling” on the TBI to fix the issue. The pilot said that the vapor lock issue likely started at the same time as the engine heated up due to the extra lean mixture. He added that the rear seal might leak and spray oil on the exhaust pipe. He stated that enriching the mixture might have corrected the issue inflight.
On May 26, 2019, about 1700 central daylight time, a Rand Robinson KR2 airplane, N886MJ, was substantially damaged when it was involved in an accident near Poplar Grove, Illinois. The pilot received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, shortly after departure, the airplane did not accelerate as expected. He smelled oily smoke, saw the oil pressure reading below normal, and noted an increase in oil temperature. The engine began losing power, so the pilot performed a forced landing to a corn field. During the landing, the nosewheel dug into the field and the airplane nosed over, resulting in substantial damage to the wings and vertical stabilizer. The airplane was examined by inspectors from the Federal Aviation Administration. Examination and borescope of the engine did not locate the source of the oil leak. The pilot later stated that he believed the engine experienced a vapor lock in the throttle body injection (TBI) system. His research with the online Corvair engine community revealed that this is an issue with high air temperatures. Other airplane owners provided “blast cooling” on the TBI to fix the issue. The pilot said that the vapor lock issue likely started at the same time as the engine heated up due to the lean mixture. He added that the rear seal might leak and spray oil on the exhaust pipe and stated that enriching the mixture might have corrected the issue.
The loss of engine power due to vapor lock of the throttle body injection system.
Source: NTSB Aviation Accident Database
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