BEECH BE-58 near Jackson, MS — 2008-06-05

Probable cause

An outboard left wing explosion during takeoff due to the improper fuel cell installation and inadequate subsequent inspections by maintenance personnel.

NTSB narrative

According to the pilot, during the takeoff roll and while traveling at about 50 knots, he heard an "explosion" and could feel a thud in the rudder pedals. He immediately looked up and saw damage on the left wing with black smoke coming out of a hole in the wing. The pilot stopped the airplane, exited and put out the fire with an onboard fire extinguisher. Examination of the airplane found a thermally damaged hose (vent line), which contained a tight hose clamp and crimped end within the clamp. The separated hose was found lying below the siphon break-bent line interconnect. The position of the clamped and crimped end was consistent with the hose being clamped prior to the break-bent line, which would have allowed the partially connected hose to separate from the break-bent line. The separation of the hose from the break-bent line interconnect would have allowed fuel vapor to accumulate within the wing's open cavities. Additionally, the landing light power wire was separated and the exposed end of the wire exhibited melting, and there was evidence of arcing that existed along the base of the structure (lighting hole) and adjacent interior upper wing skin. This arcing was likely the ignition source for the trapped fuel vapor. The outboard leading edge fuel cell was removed during the investigation and checked for leaks. The fuel cell was pressurized and an air leak was found on the aft side of the fuel cap assembly, at the interior fuel placard mounting rivets. The fuel full placard and rivets were found to be loose when moved by hand. The loose mounting rivets would have also been a source of fuel vapor, which would have contributed to the fuel vapors trapped in the wing. The left wing fuel cells were replaced about 13 months prior to the accident and the airplane's most recent 100-hour inspection was performed about 3 months prior to the accident. For 100-hour inspections, the airplane's maintenance manual contained instructions to examine fuel cells, vent lines, and electrical wiring.

Analysis

Primary failure mode

Mechanical failure

First missed decision gate

Inspect fuel cells and vent lines before takeoff to prevent fire.

NTSB coding

• Explosion (non-impact) · Takeoff-rejected takeoff
• Maintenance

Evidence available

• Photos
• 13 docket documents

Docket documents13

• Other Pertinent Forms and Reports; Aircraft maintenance records.form
• Other Pertinent Forms and Reports; Beechcraft Maintenance Checklist.form
• Other Pertinent Forms and Reports; Hawker Beechcraft Safety Communique'form
• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form
• Pilot Statementinterview
• Statement of Party Representatives to NTSB Investigationinterview
• HBC Digital Photo; Electrical Arching at Lighting Holephotos
• HBC Digital Photo; Loose Rivets on Fuel Fillerphotos
• HBC Digital Photo; Molten Wiring From Landing Light Hot Wirephotos
• NTSB Digital Photo; Clamped Fuel Vent Hosephotos
• NTSB Digital Photo; Left Wing Damagephotos
• NTSB Digital Photo; Left Wing Trailing Edge Damagephotos
• Weather Reports and Records; Metarsreport