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New Chinook models extend heavylift helicopter's life
What began as another remanufacture of the US Army's long-serving CH-47 Chinooks has evolved into a programme that will keep the heavylift helicopter in production beyond 2018 - and in service beyond 2030.
he renewal of the Chinook coincides with a renaissance of the helicopter in the aerial assault role it performed in the Vietnam War. Because of its size, the CH-47 had been reassigned to logistics missions behind the line, but the superior hot and high performance provided by its tandem rotors has made the helicopter essential to combat operations in Afghanistan. "The CH-47F is out in the front line performing aerial assault, with a fully digital glass cockpit, networked communications and state of the art aircraft survivability equipment," says programme manager Ken Eland. The special-operations version, the MH-47G, was first deployed to Afghanistan in February 2007, followed by the regular army's F model.
These helicopters are the first of a planned 452 CH-47Fs for the US Army and 61 MH-47Gs for the army's 160th Special Operations Aviation Regiment (Airborne). They are being produced under what began as the Improved Cargo Helicopter programme. This was intended to remanufacture the Chinooks to restore their life and increase their capability. At the same time as the regular army's D models were upgraded to Fs, the special operations E models were to be rebuilt as Gs.
Because of changes to the timing and scope of the programme, the CH-47Fs now rolling off the Boeing assembly line in Philadelphia, Pennsylvania are more capable machines than originally envisaged. "The F and the G were part of the same acquisition plan," says Eland. "The Gs were to be interspersed between the Fs, but then the army decided to stand up the Gs early. That gave us an opportunity to make many changes to the F."
Boeing built three CH-47Fs - two development and one low-rate initial production aircraft, the first flying in June 2001 - then switched to producing the MH-47Gs. Because Special Operations Command is both replacing attrition and increasing its fleet, the 61 G models will be a mix of remanufacturedMH-47Es and CH-47Ds.
The company looked at the gap in production as an opportunity to see what it could do with the F model. "When we went into solely G production, we took every block improvement we could into the F," Eland says. These included new airframe, digital automatic flight controls and a fully glass cockpit.
The biggest change was to introduce a cockpit based on the Common Avionics Architecture System (CAAS) originally developed for retrofitting into Special Operations Command helicopters. "They were working with Rockwell Collins to develop a common cockpit at SOCOM. We took that into the G and then used the G as the foundation for the F."
The original plan for the CH-47F was to upgrade the D model to a partial glass cockpit, with four displays and moving map, butretaining engine and other instruments.Developed by Rockwell Collins, the fully glass CAAS cockpit combines flight information, engine instruments and crew alerts on five larger liquid-crystal displays.
"The G accelerated the incorporation of CAAS onto the F," says Eland. "That avoided a big retrofit and gave us a common cockpit from the get-go. We put CAAS into the LRIP aircraft as a risk reduction, and used it for training." The plan now is to keep the hardware and software in the F and G models as common as possible. "We are working hard to maintain the same hardware level and as much software commonality as possible," he says. The CAAS software is partitioned, so new functionality can be added as plug-and-play modules without the complete system having to be revalidated (see box P45).
The CH-47F goes beyond the G, introducing the BAE Systems digital advanced flight control system (DAFCS) and integrating it into CAAS. "There is an embedded flight director in CAAS that is fully coupled to DAFCS," says Eland. The DAFCS is also integrated with the CAAS flight management system and can fly the aircraft from take-off through to hover. Replacing the existing analogue system, the DAFCS increases reliability and has built-in diagnostics to improve maintainability.
Other aircraft systems are essentially unchanged. Drive systems removed from D models are sent for "super overhaul" and emerge with "near-zero time" on the components, says Eland. The CH-47F uses the Honeywell T55-714A engine that is already replacing the -712 in the CH-47D fleet. The more-powerful -714A maintains the -712's sea-level power rating of 3,750shp (2,790kW) to 4,000ft (1,200m) and 35e_SDgrC (95e_SDgrF), providing a significant increase in hot-and-high performance.
The original plan to refurbish the CH-47D airframes was changed as it became more cost-effective to manufacture new airframe sections. Boeing is also building all-new CH-47Fs to top up the army's Chinook fleet, and soon for export customers. At the same time, the special operations MH-47Gs are all being remanufactured.
The Philadelphia assembly line, therefore, is producing new, "renew" and "reman" Chinooks simultaneously. This is possible, Eland says, because the CH-47 airframe incorporates true manufacturing splices. "You can take one piece off and put on another. One aircraft we called Mr Potato Head was put together from spare aft fuselage, cabin and cockpit."
The process begins by flying in a CH-47D or MH-47E, stripping it, taking the cockpit off, and removing the rotors and dynamic system and sending them for overhaul. "To produce a G, we take the aft fuselage and cabin, media-blast strip it to bare metal, inspect and repair." A new cockpit is then spliced on. "We bolt it right up to the D/E cabin - repeatably."
Link to the rest
http://www.flightglobal.com/article...models-extend-heavylift-helicopters-life.html
New Chinook models extend heavylift helicopter's life
What began as another remanufacture of the US Army's long-serving CH-47 Chinooks has evolved into a programme that will keep the heavylift helicopter in production beyond 2018 - and in service beyond 2030.
he renewal of the Chinook coincides with a renaissance of the helicopter in the aerial assault role it performed in the Vietnam War. Because of its size, the CH-47 had been reassigned to logistics missions behind the line, but the superior hot and high performance provided by its tandem rotors has made the helicopter essential to combat operations in Afghanistan. "The CH-47F is out in the front line performing aerial assault, with a fully digital glass cockpit, networked communications and state of the art aircraft survivability equipment," says programme manager Ken Eland. The special-operations version, the MH-47G, was first deployed to Afghanistan in February 2007, followed by the regular army's F model.
These helicopters are the first of a planned 452 CH-47Fs for the US Army and 61 MH-47Gs for the army's 160th Special Operations Aviation Regiment (Airborne). They are being produced under what began as the Improved Cargo Helicopter programme. This was intended to remanufacture the Chinooks to restore their life and increase their capability. At the same time as the regular army's D models were upgraded to Fs, the special operations E models were to be rebuilt as Gs.
Because of changes to the timing and scope of the programme, the CH-47Fs now rolling off the Boeing assembly line in Philadelphia, Pennsylvania are more capable machines than originally envisaged. "The F and the G were part of the same acquisition plan," says Eland. "The Gs were to be interspersed between the Fs, but then the army decided to stand up the Gs early. That gave us an opportunity to make many changes to the F."
Boeing built three CH-47Fs - two development and one low-rate initial production aircraft, the first flying in June 2001 - then switched to producing the MH-47Gs. Because Special Operations Command is both replacing attrition and increasing its fleet, the 61 G models will be a mix of remanufacturedMH-47Es and CH-47Ds.
The company looked at the gap in production as an opportunity to see what it could do with the F model. "When we went into solely G production, we took every block improvement we could into the F," Eland says. These included new airframe, digital automatic flight controls and a fully glass cockpit.
The biggest change was to introduce a cockpit based on the Common Avionics Architecture System (CAAS) originally developed for retrofitting into Special Operations Command helicopters. "They were working with Rockwell Collins to develop a common cockpit at SOCOM. We took that into the G and then used the G as the foundation for the F."
The original plan for the CH-47F was to upgrade the D model to a partial glass cockpit, with four displays and moving map, butretaining engine and other instruments.Developed by Rockwell Collins, the fully glass CAAS cockpit combines flight information, engine instruments and crew alerts on five larger liquid-crystal displays.
"The G accelerated the incorporation of CAAS onto the F," says Eland. "That avoided a big retrofit and gave us a common cockpit from the get-go. We put CAAS into the LRIP aircraft as a risk reduction, and used it for training." The plan now is to keep the hardware and software in the F and G models as common as possible. "We are working hard to maintain the same hardware level and as much software commonality as possible," he says. The CAAS software is partitioned, so new functionality can be added as plug-and-play modules without the complete system having to be revalidated (see box P45).
The CH-47F goes beyond the G, introducing the BAE Systems digital advanced flight control system (DAFCS) and integrating it into CAAS. "There is an embedded flight director in CAAS that is fully coupled to DAFCS," says Eland. The DAFCS is also integrated with the CAAS flight management system and can fly the aircraft from take-off through to hover. Replacing the existing analogue system, the DAFCS increases reliability and has built-in diagnostics to improve maintainability.
Other aircraft systems are essentially unchanged. Drive systems removed from D models are sent for "super overhaul" and emerge with "near-zero time" on the components, says Eland. The CH-47F uses the Honeywell T55-714A engine that is already replacing the -712 in the CH-47D fleet. The more-powerful -714A maintains the -712's sea-level power rating of 3,750shp (2,790kW) to 4,000ft (1,200m) and 35e_SDgrC (95e_SDgrF), providing a significant increase in hot-and-high performance.
The original plan to refurbish the CH-47D airframes was changed as it became more cost-effective to manufacture new airframe sections. Boeing is also building all-new CH-47Fs to top up the army's Chinook fleet, and soon for export customers. At the same time, the special operations MH-47Gs are all being remanufactured.
The Philadelphia assembly line, therefore, is producing new, "renew" and "reman" Chinooks simultaneously. This is possible, Eland says, because the CH-47 airframe incorporates true manufacturing splices. "You can take one piece off and put on another. One aircraft we called Mr Potato Head was put together from spare aft fuselage, cabin and cockpit."
The process begins by flying in a CH-47D or MH-47E, stripping it, taking the cockpit off, and removing the rotors and dynamic system and sending them for overhaul. "To produce a G, we take the aft fuselage and cabin, media-blast strip it to bare metal, inspect and repair." A new cockpit is then spliced on. "We bolt it right up to the D/E cabin - repeatably."
Link to the rest
http://www.flightglobal.com/article...models-extend-heavylift-helicopters-life.html
