Cessna 182 N9398G accident near Opelika, Alabama

Probable cause

The improper torque application and ongoing inspection of an oil filter adaptor by maintenance personnel, which resulted in a loss of lubrication and a catastrophic engine failure.

NTSB analysis

During the climb after takeoff, the pilot noticed a drop in engine oil pressure and turned back toward the airport to land. Almost immediately thereafter, the engine began to run rough and eventually lost power completely. The pilot performed a forced landing to an interstate exit ramp, during which the airplane sustained substantial damage.

Examination of the engine revealed that the Nos. 2 and 4 connecting rods were separated from their respective rod journals. All rod journals were absent of lubrication and displayed heat damage. Disassembly of the engine and the separation of the case halves revealed abnormal wear and damage consistent with loss of lubrication. Examination and testing of engine accessories revealed no anomalies that would have prevented normal operation.

The engine was equipped with a screw-on oil filter adaptor required to be torqued to 65 ft/lbs at installation, and the integrity of the oil filter adaptor installation was required to be examined during every 100-hour and annual inspection. The adaptor on the accident engine was found loose and could be easily rotated by hand through a 90° arc, and oil seepage was found on the area surrounding the oil filter adapter attachment point. Given this information, it is likely that the loose adaptor allowed the engine oil to be pumped overboard, resulting in a loss of engine lubrication and catastrophic failure of the Nos. 2 and 4 connecting rods.

Text from the NTSB. Open the NTSB docket for ERA19LA017 for the full record.