Piper PA-18-135 N802DA accident near Myrtle Beach, South Carolina

Probable cause

A loss of engine power due to thermally-induced failure of a piston. Contributing to the accident was the sustained engine exposure to abnormally high operating temperatures and detonation, and the exceedance of the engine manufacturer's recommended overhaul interval by approximately 1,200 hours.

NTSB analysis

The pilot departed on a banner tow mission to the shoreline approximately 15 miles away. Approximately 6 miles prior to the shoreline, he noted a slight loss of altitude and added power to climb. He then noticed an increase in oil temperature and a decrease in oil pressure. He initially attempted to return to the departure airport, but could not maintain altitude. The pilot set up for a precautionary landing, but was unsuccessful when the engine lost power completely. The airplane struck trees while still airborne and came to rest in an open area. The Number 4 piston exhibited evidence of sustained exposure to abnormally high operating temperatures and detonation. A portion of the piston was thermally eroded from the head to below the oil scraper ring and the sidewall was penetrated in the eroded area. The operator monitored fleet fuel consumption very closely and encouraged the pilots to regularly lean the fuel mixtures. The engine had accumulated 3,200 hours since major overhaul, which was 1,200 hours beyond the manufacturer's recommended time of 2,000 hours.

Text from the NTSB. Open the NTSB docket for NYC08LA201 for the full record.