NTSB Identification: SEA98FA109.
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Accident occurred Sunday, June 21, 1998 in CORVALLIS, OR
Probable Cause Approval Date: 01/10/2000
Aircraft: Nolley BD-5T, registration: N50TX
Injuries: 1 Uninjured.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
During the assembly of the home-built aircraft, its wet-wing fuel tanks were sloshed with a sealer (Randolph #802) that is not compatible with alcohol fuel additives. During the aircraft's three week engine test run and test flight sequence, Jet-A fuel containing an ethanol fuel additive (Prist) was in its fuel tanks. This resulted in the sloshing compound debonding from the fuel tank walls and partially blocking an in-line fuel filter. Because of this blockage, approximately 25 minutes into the fourth test flight, the aircraft experienced a total loss of power. During the subsequent forced landing, the aircraft nosed over when one of its wings became entangled in tall vegetation. During the investigation it was determined that the owner/builder, the test pilot, representatives of the company that helped mate the engine to the airframe, and the supplier of the engine/propeller/gearbox assembly, all of whom were present for the ground run and test flight sequence on that day, were not aware that an alcohol fuel additive may be present in some Jet-A fuel at the time of purchase.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The introduction of a fuel containing an ethanol additive into fuel tanks sloshed/sealed with a compound incompatible with alcohols, resulting in debonding of the compound from the fuel tank walls, leading to partial blockage of an in-line fuel filter, and a total loss of engine power due to fuel starvation. Factors include an inadequate preflight and tall vegetation in the field where the forced landing was attempted. Full narrative available
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