Page:CAB Accident Report, United Airlines Flight 21.pdf/8



Aircraft NC 25678, a DC-3A, was manufactured by the Douglas Aircraft Company of Santa Monica, California. This model was powered by two twin Wasp engines, models SIC3-G, manufactured by the Pratt and Whitney Aircraft Division of the United Aircraft Corporation, each rated at 1,100 horse power. The aircraft was delivered to United January 25, 1940, and was currently certificated as airworthy for operation with 21 passengers and a crew of three and with a standard gross weight of 24,546 pounds.

The procedure of United calls for an engine change overhaul at the end of each 625 hours of service and the record indicates that this engine change overhaul had been completed less than a week before the accident, the aircraft and engines having logged since that overhaul up to the moment of the crash only 21 hours and 15 minutes. When overhauled, the left engine (Serial No. 2621) had a total time of 2,772 hours and 44 minutes and the right engine (Serial No. 2624) had a total time 2,932 hours and 57 minutes. They were installed on aircraft NC 25678 November 28, 1940.

Company procedure also provides, at the time of the 625-hour engine overhaul, for an inspection of the aircraft itself and the replacement and repair of all parts necessary to insure the safe operation of the aircraft for the next 625 hours of service. A major overhaul of the aircraft is required at the end of each 5,000 hours of flight time but this plane, having logged a total