A oxygen leak in the high-pressure oxygen system caused an April 30 fire that heavily damaged an RC-135V Rivet Joint at Offutt Air Force Base, Nebraska, the Air Force said in a report released Friday.
Contract depot maintenance personnel from L3 Communications failed to properly tighten a retaining nut that connected a metal oxygen tube to a junction, resulting in the an oxygen leak. The oxygen-rich environment then subsequently ignited during the plane’s attempt to take off, said the report released by the Air Combat Command Accident Investigation Board at Langley Air Force Base, Virginia.
The oxygen-rich environment then subsequently ignited during the plane's attempt to take off on April 30, the report found.
No one was killed in the accident, but four crew members received medical treatment for minor smoke inhalation. No civilians or private property were involved in the incident.
The fire burned a hole through the upper fuselage of the plane, the Air Force report said, causing damage estimated at $62.4 million.
The aircraft was assigned to the 343rd Reconnaissance Squadron, 55th Wing, at Offutt Air Force Base, Nebraska, military records show.
The report said that contracted workers from L3 Communications didn’t properly tighten the nut connecting the oxygen tube, which caused the leak.But Air Combat Command said no decision has been made on whether the company would be liable for the aircraft damage, calling it a "complex subject."
"The purpose of this report is to provide a comprehensive look at all of the factors that led to this accident," ACC said in a statement. "The report does not suggest or recommend any actions, to include assigning accountability or liability. Discipline and administrative actions, if appropriate, are handled through command channels."
Air Force Times contacted officials at L3, who said they would respond to the report later Wednesday afternoon.
The RC-135V/W Rivet Joint is a reconnaissance aircraft with extensive radar and sensor capabilities that are used to gather information and coordinate missions. The Air Force has flown the craft since 1962, and it saw service in Vietnam, Iraq and Afghanistan, among other places. In 2012, the Air Force had 17 of the planes on active duty.
According to statistics from the Air Force Safety Center, the C-135 airframe – which includes the reconnaissance version of the plane – has been involved in five major accidents since 2000.
The worst came in 2013, when a KC-135 refueling tanker crashed in the Kyrgyz Republic, killing all three crew members on board.
That investigation found that a "Dutch roll" – where a flight instability causes the aircraft to drift from side to side – eventually caused enough stress to tear the tail section off the aircraft.
