Amateur-built S-12 N107JL accident near Marana, Arizona

Probable cause

The pilot's failure to conduct an adequate preflight inspection, which resulted in a loss of engine coolant during climb due to an unsecured tank cap. Contributing to the accident was the pilot's failure to use available engine power to ensure a landing on an appropriate surface.

NTSB analysis

Before the flight, the sport pilot fueled the experimental, amateur-built, light-sport airplane and conducted a preflight inspection without the aid of a checklist. He and his passenger then departed for a destination about 110 miles away. About 14 minutes after takeoff, during the climb, the passenger smelled engine coolant, and the pilot observed excessively high engine oil and coolant temperature indications. He reduced engine rpm and decided to conduct a precautionary landing at a non-towered airport south of his current position. When the airplane was north of the runway threshold, he realized that he would not reach the runway and aimed instead for the airport ramp. He then realized he would not reach the ramp and intentionally allowed the airplane to stall onto the flat earthen floor of a water catchment basin. The pilot did not use available engine power during the descent to ensure a landing on an appropriate surface, even though the engine remained running until he shut it down after impact. Examination of the airplane revealed that the engine coolant had drained in flight due to an unsecured system cap. The pilot stated that he did not check the coolant system during his preflight inspection.

Text from the NTSB. Open the NTSB docket for WPR11LA202 for the full record.