The 2022 fatal crash of a Hughes 369D was blamed on an engine compressor wheel crack.
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Fractures in the sixth-stage compressor wheel triggered a catastrophic engine failure and caused the April 2022 fatal crash of a Kestrel Helicopters 1981 Hughes 369D during long-line slinging operations in British Columbia, according to a recently released report from Canada’s Transportation Safety Board (TSB. The sole-occupant pilot died after sustaining impact forces estimated at 53 gs. He had 13,000 hours in helicopters, 11,000 hours in type, and 6,000 hours slinging cedar blocks.
The helicopter involved had accumulated 11,884 hours. At the time of the accident, the compressor on the occurrence aircraft had 15,404 hours total time in service and was due for overhaul in 353.4 hours. The sixth-stage compressor wheel, which has no life limit, had 6,646.6 hours of total time in service.
Of the two separate fractures in the Rolls-Royce 250-C20B, one was due to fatigue from shrinking voids and the other was due to resultant overstress. The TSB linked the issues to the engine’s original manufacture, and specifically the sixth-stage compressor wheels—provided by a supplier between 1986 and 2002—that were linked to two other sixth-stage failures in 1989 and 2019 due to fatigue cracks originating at shrinkage voids near the inner circumference of the wheel. The sixth-stage wheel on the accident helicopter was manufactured in 2001.
The wheel’s manufacturing process was subsequently changed, most recently in 2007, so that the part is machined from a heat-treated custom stainless-steel alloy. This offers improved mechanical strength and fatigue properties compared to the original cast sixth-stage compressor wheels. In May, the engine manufacturer re-issued Commercial Service Letter 1255, which includes a recommendation that its customers convert the compressor to the new wheel design during the next overhaul.
Fractures in the sixth-stage compressor wheel triggered a catastrophic engine failure and caused the April 2022 fatal crash of a Kestrel Helicopters 1981 Hughes 369D during long-line slinging operations in British Columbia, according to a recently released report from Canada’s Transportation Safety Board (TSB. The sole-occupant pilot died after sustaining impact forces estimated at 53 gs. He had 13,000 hours in helicopters and 11,000 hours in type.
The helicopter involved had accumulated 11,884 hours. At the time of the accident, the compressor on the occurrence aircraft had 15,404 hours total time in service and was due for overhaul in 353.4 hours. The sixth-stage compressor wheel, which has no life limit, had 6,646.6 hours of total time in service.
Of the two separate fractures in the Rolls-Royce 250-C20B, one was due to fatigue from shrinking voids and the other was due to resultant overstress. The TSB linked the issues to the engine’s original manufacture, and specifically the sixth-stage compressor wheels—provided by a supplier between 1986 and 2002—that were linked to two other sixth-stage failures in 1989 and 2019 due to fatigue cracks originating at shrinkage voids near the inner circumference of the wheel. The sixth-stage wheel on the accident helicopter was manufactured in 2001.
The wheel’s manufacturing process was subsequently changed, most recently in 2007, so that the part is machined from a heat-treated stainless steel alloy.