ATR partner Alenia Aeronautica has evaluated the carbonfibre construction and production technology it uses to build Boeing 787 fuselage barrels for the joint venture's planned all-new turboprop programme. However, the airframer has concluded that advanced aluminium alloy is the preferred material for the fuselage.
Alenia and Boeing jointly developed the mandrel wound-carbonfibre barrel production process for the 787's fuselage, which the US airframer says involves a combination of "patented and secret" technology. The Italian company is free to use the method in aircraft market sectors where Boeing does not compete.
This would allow it to be adopted for any new turboprop design developed by ATR, but technical director Carmine Orsi says that turboprop customers' preferred solution will remain the metallic skin and frame structure.
This is because the fuselage's "proximity to the ground" leaves it vulnerable to bumps from vehicles and loading equipment, and traditional construction is much more resistant to damage - and more easily repairable - than is carbonfibre.
ATR want to move beyond the 42/72-600's current partly carbonfibre wing and empennage to all-composite structures
Cabin noise would also be an issue with a carbonfibre fuselage, says Orsi. The airframer has put a lot of work into passive noise reduction engineering to quieten the ATR's interior, but the stiffer 787-style composite fuselage would be a much more efficient transmitter of vibration and noise, making the sound reduction effort much more difficult to engineer, he says.
Orsi stresses that new aluminium alloys promise to slash 7% off the weight of current fuselage skins, and that current ATR models employ a significant amount of carbonfibre structure. Customers, says Orsi, want to move beyond the ATR 42/72-600's current partly carbonfibre wing and empennage to all-composite structures and this variant will gradually evolve to have an increased carbon content.
Similarly, carbonfibre is a natural way forward for floor beams and pressure bulkheads offering a significant weight benefit. Orsi adds that much of the appeal to customers lies in carbonfibre's corrosion resistance.