Ercoupe (Eng & Research Corp.) 415-C N99180 accident near Penngrove, California

Probable cause

The loss of engine power resulting from frayed magneto "P" leads, which shorted out and killed the ignition system. Contributing to the accident was the lack of suitable terrain for the forced landing.

NTSB analysis

During cruise flight, the airplane's engine lost total power and the pilot executed a forced landing in an alfalfa field. During the landing roll in the 2 to 3-foot-tall grass, the airplane skidded sideways and the tail dug into the ground. The airplane's tail cone was buckled, and the right vertical stabilizer and rudder were bent. Federal Aviation Administration (FAA) inspectors found that both magnetos had frayed primary wires ("P" leads) at the magnetos, which could have been shorting out and intermittently killing the ignition system. They noted numerous additional maintenance discrepancies with the airplane; however, none of these would have contributed to a loss of engine power. According to the inspectors, the airplane's most recent annual inspection was completed about 2 months before the accident. The maintenance discrepancies found by the FAA inspectors, including the frayed "P" leads, should have been repaired during this annual inspection.

Text from the NTSB. Open the NTSB docket for LAX08LA142 for the full record.