Loose fuel lines lead to accidents

General Aviation News will often reprint excerpts from US National Transportation Safety Board (NTSB) accident reports, including two accidents that involved loose fuel lines after maintenance work or an inspection.

In the first accident report dated February 2010, a Piper Malibu Mirage suffered substantial damage in Nashville but luckily there were no injuries. According to the report, a 2,632-hour commercial pilot was in cruise flight when the alternator light illuminated and he smelled smoke. While diverting to the nearest airport, he lost all power on the descent but safely landed and he then noted light smoke coming from cowling for several minutes after landing.

An inspection by an FAA inspector found that the fuel control unit feed and return lines were “loose at the rear engine baffle fittings immediately above the starter and starter adapter.” A review of maintenance records showed that the starter adapter had just been replaced nine hours before the accident – meaning the mechanic had failed to properly secure the fuel control unit fuel lines.

The second accident report dated May 2010, a Piper Warrior II suffered substantial damage in Chandler (Arizona) resulting in one serious and one minor injury. According to the accident report, a private pilot and a CFI were performing touch-and-goes when smoke began to fill the cockpit – most likely coming through the defroster vents. The smoke soon became so thick that the CFI could not see outside of the windows and he ended up making a hard landing.

A review of maintenance records revealed that the last annual inspection had been completed just two days before the accident and the aircraft had flown about four hours since then. An inspection of the aircraft then revealed that the fuel line leading from the engine-driven fuel pump to the carburetor was disconnected at the fuel pump with no visible impact damage to the “B” nut on the line or to the fitting on the fuel pump – meaning the line was undone before impact. 

It was concluded that the “B” nut on the line had not been properly tightened by maintenance personnel and probably backed off due to normal engine vibration. In other words and right after maintenance, check those fuel lines!

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