19970603012809A

The aircraft was on a routine fire reconnaissance patrol. There were no eyewitnesses to the accident. ARTCC radar data showed no primary or secondary targets at of above 3000 feet AGL. No record was found that either crew member initiated an emergency transmission. No weather phenomena was observed by any source in the area. The aircraft crashed at the apex of a river bed in a narrow canyon at an elevation of 5620 feet MSL, and came to rest on a sandbar with a measured 400 foot radius bend in the river. The wall on the west side of the river rises steeply to about 6100 feet MSL, and the terrain on the east side rises to equal heights over a slightly longer horizontal distance. The trim speed of the aircraft was computed by Beech aircraft at 120 knots based on the elevator trim tab position in the comparison to the gross weight and CG. A 73 degree bank angle is required for the aircraft to make a 400 foot radius turn at 120 knots. The aircraft stall speed at that bank angle is 111 knots. An extensive postcrash fire comsumed the aircraft and no ground scars were observed outside of the immediate area of the main wreckage. The propeller asssemblies were impacted into the ground at angles of 35 to 40 degrees, and all other aircraft structural components were deformed at similar angles. No preimpact failures or system/component malfunctions were found. Both propellers were operating symetrically, with blade angles in the governed range. A review of past reconnaissance flights over this same route disclosed that the flights position reports and computed ground speed was consistent with all past flights.