Amateur-built RV8 N6948L accident near Corona, California

Probable cause

Fuel contamination from the pilot’s improper application of a sealant to the fuel tank, which resulted in a partial loss of engine power on takeoff.

NTSB analysis

Shortly after takeoff, the airplane climbed to about 95 ft above ground level and then made a shallow descent and turned left. The airplane collided with a road and hit a berm before becoming engulfed in flames. Witnesses reported that the engine sounded like it was producing partial power.

The pilot had flown the airplane to the departure airport about a month before the accident to have it painted at a shop there. The accident flight was the first flight after it was painted. The left fuel tank was likely empty because the pilot had drained and repaired it before flying to the airport, and no evidence was found of the airplane being refueled at the airport. Based on his receipts, the pilot had used an alcohol-resistant gas tank sealer to repair the fuel tank.

Postaccident examination of the fuel system revealed a hardened white material throughout the fuel system, including in the fuel filters and the mechanical fuel pump. The material was analyzed by the NTSB Materials Laboratory to determine its chemical composition. The tested samples were consistent with materials in the alcohol-resistant gas tank sealer.

Based on the presence of hardened white material throughout the fuel system, the pilot likely applied the gas tank sealer improperly. The sealer manufacturer stated that if the tank is not dry before applying the sealer or has foreign matter, it may prohibit the sealer from adhering and then lead to it coming loose, eventually entering the fuel system and blocking the fuel pump. In addition, if the airplane was refueled after the sealer was applied but not fully dried, any liquid sealer remaining in the tank likely would have coated the fuel system components as found after the accident.

Text from the NTSB. Open the NTSB docket for WPR24FA056 for the full record.