Airworthiness Directives; Bell Helicopter Textron, Inc. Model 47B, 47B-3, 47D, 47D-1, 47G, 47G-2, 47G2A, 47G-2A-1, 47G-3, 47G-3B, 47G-3B-1, 47G-3B-2, 47G-3B-2A, 47G-4, 47G-4A, 47G-5, 47G-5A, 47H-1, 47J, 47J-2, 47J-2A, and 47K Helicopters

This document publishes in the Federal Register an amendment adopting superseding Airworthiness Directive (AD) 2000-18-51 which was sent previously to all known U.S. owners and operators of Bell Helicopter Textron, Inc. (BHTI) Model 47B, 47B-3, 47D, 47D-1, 47G, 47G- 2, 47G2A, 47G-2A-1, 47G-3, 47G-3B, 47G-3B-1, 47G-3B-2, 47G-3B-2A, 47G- 4, 47G-4A, 47G-5, 47G-5A, 47H-1, 47J, 47J-2, 47J-2A, and 47K helicopters by individual letters. This AD requires recurring liquid penetrant or eddy current inspections of the main rotor blade grip (grip) threads for a crack. If a crack is detected, this AD requires, before further flight, replacing the cracked grip with an airworthy grip. This AD also establishes a retirement life of 1,200 hours time- in-service (TIS) for each grip. This amendment is prompted by the results of an investigation of an August 1998 accident in which a grip failed on a BHTI Model 47G-2 helicopter due to a fatigue crack. An analysis of the field service data revealed fatigue cracks in 70 percent of the grips inspected. The actions specified by this AD are intended to prevent failure of a grip, loss of a main rotor blade, and subsequent loss of control of the helicopter.