The July 10, 2021, fatal crash of a Beechcraft King Air C90 was caused by “separation of the left wing’s outboard section due to a fatigue crack in the lower spar cap,” according to the NTSB final report published late last week. “Contributing to the accident was the failure of the non-destructive-testing (NDT) inspector to detect the crack” and the “operator’s decision to repair the wing spar instead of replacing it as recommended by the aircraft manufacturer,” the safety agency said.
The turboprop twin was being operated as a public-use firefighting aircraft conducting reconnaissance and supervision. It was about 2,300 feet agl over an area of fire near Wikieup, Arizona, when the left wing separated. Killed were the pilot and an aerial tactical supervisor. Missions are typically flown at speeds from 120 to 150 knots and require steep bank angles.
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