THE FATAL CRASH of a Learjet 35A on 14 December, 1994, in Fresno, California, was caused by improperly installed electric wiring which led to an inflight fire, says the US National Transportation Safety Board (NTSB).
Two pilots were killed and 21 people on the ground injured when the Learjet 35A, operated by Phoenix Air under contract to the California Air National Guard, crashed during an emergency landing.
The aircraft was one of Phoenix Air's 18 Learjets modified to accept two wing-mounted electronic-warfare pods. Phoenix Air worked on 15 of the 18 Learjets, with another company completing the other three. The crash occurred after a routine training mission.
After inspecting the company's aircraft, NTSB investigators concluded that all 15 Learjets modified by Phoenix Air, including the crashed Learjet 35A, had been mis-wired and mis-inspected.
The agency says that the fire "...most likely originated with a short of the special-mission power-supply wires in an area unprotected by current limiters". After receiving a false engine-fire warning, the pilots shut down the left engine. The fire resulted from a fuel line ruptured by an exploding battery.
Phoenix Air says, "The mission power wires, may or may not have been, a factor in the start of the fire. There are serious questions, which remain as to whether the mission power cables were a cause of the fire, or if they were a casualty of some other fire source, either before or after the aircraft crashed."
The NTSB says that there was inadequate oversight of Phoenix's maintenance. It recommends that the FAA publish an airworthiness-information bulletin describing the circumstances of the accident and emphasizes that major aircraft modifications be performed strictly to technical specifications.
Source: Flight International
