The Army has not made any requests, but Boeing expects Congress to add CH-47s to the service’s fleet.
Boeing is bullish on Capitol Hill adding more unrequested Chinook heavy-lift helicopters to the U.S. Army’s fleet and is pressing to add even more capability by reviving a rotor blade upgrade the service had sought to end and angling for a new engine to go into future helicopters.
Meanwhile, the Army wants to take its time deciding whether to move ahead with the Block II full-rate production for its Chinooks as it goes through a heavy-lift study that began this year, with the decision expected to be laid out in next year’s budget cycle.
- German order could ease production stress
- Boeing keeps new rotor blades alive, teasing new engine
“The Chinook’s going to be around for a while, it really is,” Army Chief of Staff Gen. James McConville said April 27 at the Army Aviation Association of America symposium. “I don’t see the Chinook going anywhere. The challenge that the [next] chief and secretary have will be about priorities.”
Those priorities mean keeping the focus on the service’s Future Vertical Lift programs. The Army elected to stop buying the Chinook for its regular forces in its fiscal 2021 budget request, but Congress added four more as part of that budget without any request. That was followed by two more in 2022 and four more in 2023. The first of the initial four will be delivered in 2023, and the Army is determining where they will go.
Ken Eland, Boeing’s Chinook program manager, says the company expects another plus-up in this budget cycle, and the company has targeted keeping that four-aircraft-per-year goal. “Traditionally, that is a number we’ll stand behind. It’s not asking Congress for too much additional funding,” he says.
Boeing is continuing Chinook production at its minimum sustainable rate of about 18 per year as it awaits the Army’s full-rate production decision. In the meantime, the company is awaiting approval from Germany to move ahead with an order of 60 CH-47F Block IIs that would fill up production slots. That letter of offer and acceptance is still being worked by the U.S. State Department and is expected to go back to Germany for parliamentary approval at the end of May.
The German order follows a contract with Egypt in December for 12 CH-47Fs and South Korea’s finalized order for 18 of the helicopters.
U.S. Army officials have highlighted these sales—Germany’s order in particular—as ways to keep Boeing’s production healthy as it works through the decision. Doug Bush, the service’s assistant secretary for acquisition, logistics and technology, told a House Armed Services tactical air and land forces subcommittee in April that the German order along with ongoing special operations orders would help to retain the workforce and “buys us some more time.” However, Boeing says this would maintain only the minimum sustainable rate. The company wants to achieve a rate of 30-36 aircraft per year.
“It’s just keeping alive; it’s not the efficiency that you look for in a real production program,” Eland says.
The production decision will be based on the timing and affordability of the program, he says, not the capability of the Block II aircraft. The upgraded helicopter includes advanced communications and navigation, open systems architecture, redesigned fuel systems and an improved drive train, and its gross weight has increased to 54,000 lb. from 50,000 lb. The engineering and manufacturing development (EMD) test aircraft flew more than 800 hr. as part of the EMD phase, collecting about 3,200 data points, and now the company wants to see what other performance it can “squeak out.”
Notably, Boeing is keeping alive the Advanced Chinook Rotor Blades (ACRB), which were not included in the low-rate initial production lots because of issues that developed during testing. Early trials showed significant vibration that caused a safety-of-flight hazard. Eland says Boeing is keeping the development of the blades “on life support” and is willing to fund development to prepare them for production and to go back into qualification, although it is not clear that the Army would be interested.
Without the ACRB, Boeing was able to increase performance with other changes such as adjustments to the drive system, flight controls and the new fuel system, Eland says.
Honeywell and the Army have signed a cooperative research and development agreement (CRADA) for a drop-in engine for the CH-47, the T55-714C. The 6,000-shaft-hp engine is 20% more powerful and consumes 8% less fuel than the existing T55-714A. John Russo, Honeywell vice president and general manager of military engines, says the powerplant is in development testing and flight clearance trials ahead of delivery in 2024. The company redesigned the engine for reliability by reducing the parts count and repositioning externals to enable easier access for maintenance.
Boeing also is interested in another Honeywell engine for the Chinook: the HTS7500 that powered the Sikorsky-Boeing Defiant X Future Long-Range Assault Aircraft prototype. This is a “more advanced engine” with a significant increase in capability that would be applicable on the heavy-lift aircraft, Eland asserts. “I tend to be greedier. If you’re going to do an engine, make it a big-bang kind of thing. You have the opportunity to do something revolutionary as opposed to just evolutionary,” he says.
For Honeywell and the Army, the focus now is on executing the CRADA for the -714C. The HTS7500 has a similar architecture, with the same compressor section, flow and pressure ratio and an increased power turbine. There are discussions with customers on future uses for that engine, Russo says. For the Chinook, the -714C would be incorporated at overhaul and minimize the number of aircraft parts thrown away. “It gives us the lowest-cost, lowest-risk engines the Army needs at the right time,” Russo says.
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