Older types called in to help with search and rescue as Cormorant availability declines
AgustaWestland efforts to solve tail-rotor cracking in Canadian Forces CH-149 Cormorant (EH101) helicopters have suffered a setback, with cracks developing in five out of 22 newly manufactured rotor half-hubs delivered since July.
The cracks in the newer half-hubs, which AgustaWestland produced differently in an effort to solve the cracking problem, are in a different location than encountered previously and harder to spot, which has caused the air force to double the frequency of tail-rotor inspections to every 25h from 50, the Department of National Defence (DND) says.
Since May, the number of cases of cracking in the original, composite tail-rotor half-hub has increased from 89 to 106, not counting the cracks in the revised version. AgustaWestland says it is now flight testing a titanium-reinforced half-hub it hopes will resolve the issue, but this won’t be available for “a few months yet”.
“Some EH101 customers have at some stage suffered minor cracking in that area,” AgustaWestland’s Team Cormorant says. “The integrity of the structure is still sound and we do not have a safety concern, but we have shortened the inspection period.”
Canada says it is temporarily replacing CH-149s at 8 Wing in Trenton with older CH-146 Griffons (Bell 412HPs) in the search and rescue (SAR) role because of the problem.
Cormorant fleet availability has dropped to a 12-month average of 45% from a nine-month average of 50% as of May, with 17 additional cases of cracking in the last four months bringing the total number of damaged hubs to 106. Canada has 15 CH-149s, operating from its Comox, Gander, Greenwood and Trenton bases. Three Griffons are scheduled to take over SAR duties at Trenton in mid-October, and will probably stay in that role until “at least” the second quarter of 2006, the DND says. Two CH-149s have been reassigned to eastern Canada to “provide the remaining Cormorant squadrons with a sufficient number of available aircraft to better maintain aircrews’ skill and proficiency levels”, the DND says.
“DND continues to work towards developing a solution with AgustaWestland… to determine the cause of cracking in the tail-rotor assembly, and IMP Group, the aircraft maintenance contractor, to address spare parts availability,” the DND adds.
The Canadian fleet is still operating under performance restrictions imposed in November 2004, with a 2h limit on training flights, a maximum climb rate of 1,000ft/min (5.08m/s) and a maximum air speed of 135kt (240km/h).
ANDRZEJ JEZIORSKI/VANCOUVER
Source: Flight International