48-10-02: Rotor Blade Rework

48-10-02 BELL: Applies to Models 47B Series and 47D. Compliance required by April 1, 1948. As a precautionary measure, remove main wood rotor blades and inspect area between the outboard edge of face plates and inboard edge of fiberglass cover, and also the extreme butt end for wood checks or cracks. When inspection is completed, the extent of check, cracks and wood condition found should be reported to the manufacturer who has provided forms for this purpose in his Service Bulletin. Report also if inspection results reveal no checks or cracks. Upon completion of inspection and prior to flight the cracks should be filled with Minnesota Mining and Manufacturing Co. 3M adhesive filler No. EC612. After the filler has dried, five brush coats of Minnesota Mining and Manufacturing Co. adhesive sealer No. EC498 should be applied to the inspected area. If no checks or cracks are present, only the five brush coats of sealer must be applied. (Bell Service Bulletin No.47C47, revised March 4, 1948, contains more detailed information on this subject.)