Engineering change proposal (ECP) 6038 is intended to allow Block 2 upgrades to be affordably implemented, while supporting Boeing's goal of reducing unit cost to $40 million by 2005. Goals include reducing assembly cycle time. Keel build-up to fuselage splice time will be reduced from 34 to 24 months this year, and to 18 months in 2003, says ECP 6038 programme manager Randy Harley.
The goals are met by a full redesign of the forward fuselage to reduce parts count and improve assembly access. It will "unitise" the structure, with monolithic carbon-fibre skins and fewer frames machined from solid rather than built up. "Unitising the structure reduces work content, and improves routing and access for subsystems," says deputy programme manager Bill Carrier. Parts count is cut by 40% and fasteners by 51%.
Key constraints included limited funding, and the need to retain the outer-mould line and avoid the cost of requalifying the forward fuselage. The gun, refuelling probe, crew seats, canopy and nose-gear had to stay in the same place, and the structural response to carrier loads had to be identical. Designers also had to interface with the existing Northrop Grumman-produced centre fuselage.
ECP 6038 was an opportunity for Boeing to apply advanced design tools prototyped on the X-32 Joint Strike Fighter concept demonstrator and X-45 unmanned combat air vehicle. "We have a highly integrated, multi-disciplinary set of tools," says Carrier. All design is in three-dimensional solid models, and geometry is exported from the digital database to analysis tools, including "virtual prototypes" for manufacturing, assembly and supportability simulations. "Before we were limited by the computer capacity. Now we can visualise the entire forward fuselage in an immersive environment," he adds.
Structural test article assembly will be completed in December. The new forward fuselage will be attached to an existing F/A-18 test article for two lifetimes of fatigue testing, followed by static testing. The first Super Hornet with the forward fuselage will be the two-seater F84, build of which has been brought forward by six months to allow a validation phase. Assembly will begin in the third quarter of 2003.
Source: Flight International
