Accident Summary
A Douglas DC-3 was cruising at flight level 115 between Burbank and Hawthorne when the number 2 engine failed. The crew shut down the engine and feathered the propeller. At 20:50 EDT, the crew radioed Tonopah, Nevada, indicating their intention to make an emergency landing there. At 20:58 EDT, the number 1 engine lost power, and its propeller could not be feathered. The crew initiated an emergency glide toward Mud Lake airfield. To maintain an airspeed of 110 knots, a rate of descent of 2,000 feet per minute was required. During the descent, all electrical and hydraulic power was lost. The DC-3 struck the ground in a 10- to 20-degree nose-down attitude during the flareout and subsequently overturned.
Events
The flight was conducted between Burbank and Hawthorne. After the initial engine failure, the crew sought an emergency landing at Tonopah. However, the second engine failed before reaching the airport, forcing a descent to the unlit Mud Lake airfield. The loss of electrical and hydraulic power compounded the difficulty of the approach and landing.
Maintenance Findings
Investigation revealed numerous maintenance irregularities, including improperly adjusted valve clearances, improperly adjusted voltage regulators, and improperly installed cylinders. The aircraft was equipped with two 28-volt DC generators and one 12-volt battery, yet all electrical components other than the starters were designed for 12-volt DC operation. All maintenance was performed by companies other than the operator, and in many instances, inadequate and incomplete records failed to reflect the work accomplished.
Probable Cause
The official probable cause was determined to be an in-flight failure of both engines caused by a fatigue failure on the right engine number 12 cylinder and failure of the left front master rod bearing, necessitating a night emergency landing on unlighted terrain. Inadequate maintenance and inspection were also cited.