Amateur-built RANS S 12XL N124LP accident near Guanica, Puerto Rico

Probable cause

The pilot/owner's failure to maintain the engine in accordance with manufacturer guidance, which resulted in the undetected corrosion of the power takeoff bearing, subsequent bearing failure, and a total loss of engine power.

NTSB analysis

The sport pilot was conducting a cross-country flight in the light sport airplane when, after about one hour of flight, the engine first experienced a partial loss of power, followed shortly thereafter by a total loss of power. The pilot twice unsuccessfully attempted to restart the engine using the emergency checklist before performing a forced landing to a field. During the landing, the airplane sustained substantial damage to the fuselage.

The engine was manufactured about 10 years before the accident and maintenance logs indicated that it had not been overhauled since that time. Examination of the engine revealed that connecting rod bearing material was distributed throughout the power take off (PTO) section of the engine. Furthermore, corrosion was noted on the PTO connecting rod and connecting rod bearing. Although the engine had not yet reached the manufacturer's recommended 300 flight hour time limit for overhaul, it had exceeded the recommended 5-year calendar time limit for overhaul by 5 years. It is likely that a piece of the failed bearing became lodged in the rotary valve disc, which prevented the disc from rotating, and subsequently blocked the air and fuel to the engine, which resulted in a total loss of engine power. Had the engine been overhauled, the corrosion likely would have been discovered and the inflight loss of power prevented.

Text from the NTSB. Open the NTSB docket for ERA16LA076 for the full record.