Operators of Bell 47 helicopters have received some relief in the final version of the US Federal Aviation Administration's airworthiness directive (AD) on main rotor blade grips.
The original emergency AD effectively grounded the US fleet because of the short inspection interval and the lack of replacement grips. The final AD extends the inspection interval from 100h to 300h after an initial eddy-current inspection for thread cracks on both grips. But the FAA still requires grips to be retired after 1,200h, instead of the 2,500h sought by operators.
Availability remains a problem. Bell stopped producing the original grip earlier this year and a redesigned part will not become available until after the new AD takes effect next month.
Source: Flight International
