A special airworthiness information bulletin (SAIB) for Bell 47 helicopters, issued February 12 by the FAA, indicates the agency is considering limited relief from an onerous airworthiness directive (AD) on the rotor blade grips of those helicopters. AD 2000-18-51 was originally issued in August 2000 and effectively grounded the majority of the venerable Bell 47 helicopters in the United States.
AOPA, the Experimental Aircraft Association, Bell Helicopter, and Bell 47 users had asked for a revision of the AD in a meeting last week with the FAA's Rotorcraft Directorate in Fort Worth, Texas. The resulting SAIB SW-01-13 indicated that the agency is considering revision of the AD, possibly allowing longer times between inspection of the blade grips. The FAA also said that eddy current testing would become the inspection method of choice, rather than the less effective dye penetrant inspection.
Many Bell 47 operators are worried about the scarcity of replacement blade grips. Although Bell Helicopter is redesigning the part, new grips are not expected to be widely available until late this year. In the interim, the company has said it will manufacture only a very limited numbers of current design replacement parts.
The FAA told AOPA a revised AD might be issued in about six weeks. The FAA also said it would continue issuing alternative means of AD compliance (AMOC) authorizations that allow operators to use current blade grips up to a life of 2,500 hours.
AOPA had supported research by EAA and Bell 47 operators that showed blade grip failures are not as widespread as the FAA had originally thought. Also, aviation authorities in Australia and Canada have adopted longer blade grip inspections and increased parts retirement intervals as suitable solutions. Data from Bell 47 accidents in those countries served as the basis of the U.S. AD.
AOPA figures show more than 1,000 Bell 47 helicopters still operating in the United States.