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The initial impact occurred 335 feet short of the threshold of Runway 34L at Salt Lake City Municipal Airport, and prior to contacting the threshold lights the right and left main landing gear began to separate from their attachment points.[1] The aft lower portion of the fuselage contacted the runway and the aircraft continued sliding on the fuselage and nose gear approximately 2,838 feet. During the skid it veered to the right and came to rest 150 feet east of the runway on a heading of 123 degrees. The No. 1 engine separated and came to rest approximately 140 feet north of the aircraft.
Examination of the wreckage revealed that the landing gear was down and locked, landing flaps and leading edge devices were fully extended, and spoilers were retracted. The horizontal stabilizer was set at 8-3/4 units noseup and sustained downward bending. There was no evidence of flight control difficulty prior to impact.
Severe upward and rearward impact forces from the right main landing gear assembly produced a large impact hole and ruptured fuel lines and the No. 3 generator leads between fuselage station 1030 and 1130 on the right side. The fuel was ignited by sparks from the fuselage scraping on the runway and/or the severed generator leads. The hole and fire damage area extended circumferentially from the lower sill of the aft cargo compartment door to the top of the fuselage. The entire roof and cabin area forward of this was consumed by fire which was initially being supplied fuel under pressure by the operating boost pumps. All flight control cables, fuel supply lines from the Nos. 2 and 3 tanks, and the No. 3 generator leads which are routed through the cabin floor beams in the area of the impact hole were consumed by fire. Only a 5/8 inch stainless steel hydraulic pressure line remained intact.
All systems were operating properly prior to impact, and the crew reported no difficulty or warning lights. They did not actuate any switches or controls prior to leaving the aircraft.
The left main landing gear crushed the lower half of the No. l engine air inlet cowl aft to the compressor inlet station. Foreign object damage (FOD) extended through all compressor and turbine stages of the engine. The No. 2 engine sustained heavy FOD on the first stage of the compressor, with additional damage sustained decreasing from the second through the seventh stages. The No. 3 engine received FOD throughout all 13 stages of both compressor sections, decreasing from severe at the front to slight at the rear.
All engines were found to be capable of producing rated engine power prior to impact. The eight fuel boost pumps were tested and only two, each from a different tank, failed to meet specifications. The compressor bleed valves, which facilitate spool-up of the engines, were all operationally tested and found satisfactory. Testing of the three engine fuel controls revealed that Nos. 1 and 2 were normal and No. 3 produced an engine response approximately one second slower than normal. The aircraft fuel tanks remained intact, and all fuel shutoff valves were open.
1.13 Fire
- ↑ The B-727 landing gear is stressed to withstand an impact velocity of approximately 12.5 feet per second.
