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Sikorsky has retrofitted some of the six CH-53K King Stallion test aircraft with a fix for engine exhaust re-ingestion that has delayed development of the heavy-lift helicopter ahead of cutting the tweak into production.
In December, the company announced a fix for the problem of the 53K’s three General Electric T-408 engines sucking in their own hot exhaust, which can degrade engine performance and potentially damage the powerplants. Among other issues, the phenomenon has delayed acceptance by the U.S. Marine Corps.
Running the fix on the some of the test aircraft, now in initial operational test and evaluation (IOT&E), has validated it, and Sikorsky is preparing to cut the modification into its active production line in Stratford, Connecticut, said Nathalie Previte, vice president of strategy and business development. There are currently two production aircraft on the line in Stratford, Previte said.
“The solution has provided the level of confidence to move forward on our test program,” Previte said at the 2020 HAI Heli-Expo. “In edition, modifications will be cut into our IOT&E aircraft, so they will be introduced on our production line.”
Sikorsky, Navy and Marine Corps engineers began tackling the problem in April, and during more than 30 test events whittled a list of 135 possible design solutions to one that was retrofitted onto test aircraft for validation. The test fleet has racked up more than 1,600 flight hours, Previte said.
“Because of our early investment we have made with an all-digital design, that investment enables Sikorsky engineers and their team to resolve the exhaust gas re-ingestion situation,” Previte said.
Sikorsky is on contract for the first 14 King Stallions for the Marine Corps. Deliveries should begin in 2021. Previte said the fix has not affected the planned dates for initial operational capability by 2023.
“We are on track to meet the milestone date for the U.S. Marine Corps in terms of IOC and deployment,” Previte said.