Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, 269D, and TH- 55A series helicopters. This proposal would require a visual inspection of the bond line between the main rotor blade (blade) abrasion strip (abrasion strip) and the blade for voids, separation, or lifting of the abrasion strip; a visual inspection of the adhesive bead around the perimeter of the abrasion strip for erosion, cracks, or blisters; a tap (ring) test of the blade abrasion strip for evidence of debonding or hidden corrosion voids; and removal of any blade with an unairworthy abrasion strip and replacement with an airworthy blade. This proposal is prompted by four reports that indicate that debonding and corrosion have occurred on certain blades where the blade abrasion strip attaches to the blade skin. The actions specified by the proposed AD are intended to prevent loss of the abrasion strip from the blade and subsequent loss of control of the helicopter.