Events
Approximately five and a half minutes after departure and while the aircraft was climbing en route, an unknown ignition source triggered an explosion of fuel/air vapor within the interior of the left wing. The explosion caused loss of wing skin from both the upper and lower wing surfaces, although the wing structure remained integral. The pilots continued to fly the aircraft, executing a 180-degree course reversal back to McCarran International Airport.
Subsequent to the explosion, a fire developed within the left engine area. As the aircraft continued towards McCarran, airspeed gradually diminished. The landing gear were lowered, and shortly thereafter, the left wing entered a stall condition. This stall was brought about by a decrease in airspeed as well as the degradation of lift-developing capabilities due to the explosion-induced damage. The aircraft then entered an uncontrollable left roll several hundred feet above ground, from which a successful recovery could not be executed. Both occupants were killed.
Probable Cause
The official findings identified four occurrences:
- Occurrence #1: Explosion during climb to cruise, caused by fuel fumes in the wing.
- Occurrence #2: Fire in the left engine assembly during maneuvering (turn to reverse direction).
- Occurrence #3: Loss of control in flight during emergency descent, attributed to inadequate airspeed (pilot in command), anxiety/apprehension (pilot in command), and premature gear extension (pilot in command).
- Occurrence #4: In-flight collision with terrain during uncontrolled descent, with remedial action not possible for the pilot in command.