On October 27, 1993, a Beech F33A (registration N6333Y) was involved in an aviation accident near Saint Paul, MN. Investigators recorded the probable cause as: A 'B' nut attaching the fuel line to the mechanical fuel pump had backed off. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
After a mechanical fuel pump replacement, a pilot experienced fuel pressure loss during cruise, forcing a night landing. Examination found a loose B nut on the fuel line.
Accident Flight
During a cruise flight, the pilot observed a loss in fuel pressure. The pressure drop continued, ultimately requiring the pilot to execute a forced landing at night. The aircraft struck a fence and guard rail posts during the landing.
Maintenance History
Prior to the accident flight, the mechanical fuel pump had been removed and replaced to comply with an airworthiness directive. The accident flight was the first flight conducted after this maintenance work.
Examination Findings
A subsequent examination of the aircraft revealed that a 'B' nut attaching the fuel line to the mechanical fuel pump had backed off. No other discrepancies were noted.
Probable cause
A 'B' nut attaching the fuel line to the mechanical fuel pump had backed off.