PAUL LEWIS /WASHINGTON DC
Overhaul irons out programme's aerodynamic, structural and avionics problems
The US Marine Corps believes fixes are in place for the aerodynamic, structural and avionics problems that have plagued development of the Bell AH-1Z/UH-1Y. The difficulties forced a restructure of the $6.2 billion modernisation programme in order to avoid cancellation by the Department of Defense nine months ago.
"We're confident in the programme now. All five machines are flying and are well into testing, having just completed envelope expansion of the AH-1Z," says Col Doug Isleib, USMC H-1 programme manager. Riding on this success is a funding request in the next budget for the first low-rate initial production batch of six AH-1Z Super Cobra attack helicopters and three UH-1Y utility machines.
A solution to the premature delamination of the AH-1Z yoke has been identified, says Isleib. The yoke will be reinforced using thicker plys and a new adhesive, while the rotor RPM has been increased by 3% to alleviate loads. The horizontal stabiliser travel has been made moveable to offset automatically centre-of-gravity changes and reduce bending of the yoke. The stabiliser is larger and no longer has end plates.
"We want to increase the life of the yoke and reduce operation and support costs. Bell and government engineers agree that after the changes, 80% of yokes still be on the helicopter after 10,000h and about 90% after 5,000h," says Isleib.
After earlier software development delays, the USMC says Northrop Grumman is now meeting the delivery schedule. Block 2.3 is flying and will be upgraded to Block 2.4 in the third quarter for Phase 2B operational testing. This will provide a fully integrated suite, including the Thales Top Owl helmet mounted display, but not weapons, which will be included in the final Block 2.5, scheduled to be ready by the start of operational evaluation in August 2004. Thales delivered the first helmet to Northrop Grumman in November for testing at its system integration laboratory.
With the flight envelope complete and new sequential software coming online, flight testing is shifting to systems, including the automatic flight controls, the Lockheed Martin Target Sight Systemand electromagnetic compatibility. Sea Trials are planned for later this year.
Source: Flight International
