Piper J4A accident near Omaha, Nebraska, May 30, 2021

The NTSB's narrative final · quoted from the NTSB record

During takeoff, the airplane traveled about three-quarters of the way down the runway and climbed to about 300 ft above ground level. The engine sputtered once and stopped producing power. The pilot switched the fuel selector from the forward fuel tank to the auxiliary fuel tank and unsuccessfully tried to restart the engine. The pilot maneuvered the airplane for a forced landing, and the airplane impacted the ground. The pilot reported that fuel was pouring into the cockpit after the airplane came to rest, and he quickly exited the airplane. The airplane sustained substantial damage to both wings and the fuselage. A postaccident examination revealed that the forward fuel tank cap was not the correct part for the airplane; the cap had an unknown part number etched on it with no manufacturer name displayed. The fuel tank cap appeared to be manufactured with a single vent hole and was equipped with two worn gaskets stacked under the cap. The lower gasket had multiple visible cracks present on both sides of it. The upper gasket was wrinkled and was displaced toward the vent hole, which blocked the venting capability of the fuel tank. For the accident model airplane, the sole source of venting for the forward fuel tank was through a vented fuel tank cap. The pilot reported that the forward fuel tank cap was on the airplane when he purchased it several years ago. The pilot did not have any knowledge of the origin or the background of the forward fuel tank cap. It is likely the engine sustained fuel starvation during the takeoff due to blockage of the forward fuel tank cap vent hole. Based on the available evidence, it could not be determined when the vent hole became blocked. The accident occurred 39 days and 2.3 flight hours after the most recent annual inspection. During the inspection, the mechanic should have observed the multiple visible cracks present on both sides of the lower gasket in the fuel tank cap. Further, during the preflight inspection, the pilot should have observed the multiple visible cracks present on both sides of the lower gasket in the fuel tank cap. Had the deficiencies with the fuel tank cap gasket been observed during the annual inspection or preflight, it is likely the fuel tank cap would have been replaced.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.

Photographs from the investigation 10 pictures from the NTSB's docket, as the NTSB released them

Photo 1 – Left side view of the airplane at the accident sitePhoto 2 – Front view of the airplane at the accident sitePhoto 3 – Rear view of the airplane at the accident sitePhoto 4 – Front left view of the airplane after it was recovered from the accident sitePhoto 5 – View of the propeller after it was recovered from the accident sitePhoto 6 – Front view of the engine after it was recovered from the accident sitePhoto 7 – View of the fuel cap installed on the forward fuel tankPhoto 8 – View of the forward fuel tank cap with an engraving that shows part number 2501621Photo 9 – View of the forward fuel tank cap showing cracks in the sealPhoto 10 – View of the forward fuel tank cap showing the sole vent hole blocked by a worn seal

The NTSB's photographs with the NTSB's captions, at screen size. Open a picture to see it full size or to report one that should not be shown.