From Janes:
The US Department of Defense (DoD) is looking to address ongoing problems with the Sikorsky CH-53K King Stallion's main gearbox (MGB) by sourcing an alternate supplier.
The Naval Air Systems Command (NAVAIR) issued a solicitation on 22 April for alternative sources for the MGB to mitigate current production risk and secure volume increases for future production.
The CH-53K is fitted with an advanced drive system incorporating a multiple-path split-torque gearbox with load-sharing capability, which enables the helicopter to use the extra power of the three General Electric T408-GE-400 turboshaft engines.
This gearbox was one of three critical technologies on the helicopter that had not reached the desired levels of maturity by the time system development was launched in late 2005. Problems still had not been fully resolved in 2014 when a redesign of the MGB delayed the aircraft's maiden flight, which was finally achieved in October 2015. The US Office of the Director, Operational Test and Evaluation (DOT&E) 2018 report released earlier this year noted the MGB's low reliability and reduced service-life projections.
According to NAVAIR's request for information (RFI), the alternate supplier would participate in the CH-53K programme as a sub-contractor to Sikorsky, which is "the only contractor with the requisite knowledge, experience, and technical data that can meet the government's requirements on a timely basis".
As outlined in the report, the MGB is one of eight design deficiencies discovered during early testing. The others comprise airspeed indication anomalies, hot gas impingement on aircraft structures, tail boom and tail rotor structural problems, overheating of main rotor dampers, fuel system anomalies, high temperatures in the number two engine bay, and hot gas ingestion by the number two engine, which could reduce available power.
Wow! Does not get more humiliating than to get your own design taken away from you. If as suspected the transmission is an issue on SB-1 (epic loads) this is another nail in its coffin.