59-20-01 VERTOL: Applies to all Model 44 Series Helicopters.
Compliance required as indicated.
Due to recent failure of a strap, unless already accomplished, all straps P/N 42R1011-1 of spar weight assembly P/N 42R1009-1 in all metal forward rotor blades are to be inspected within the next twenty hours of flight in accordance with Vertol Engineering Order No. 7A (Drawing No. 42R1011). Straps found satisfactory under these inspections are acceptable for 600 hours' retirement life. Straps found with crack indications are to be replaced immediately.
When replacement straps P/N 107R1211 are incorporated, the provisions of this directive no longer apply.
This supersedes AD 59-11-02.