AD 76-26-05

76-26-05 MESSERSCHMITT-BOLKOW-BLOHM (MBB): Amendment 39-2794. Applies to all Model BO-105A and BO-105C helicopters, certificated in all categories, incorporating main rotor brake system, MBB P/N 105-10501. Compliance is required as indicated, unless already accomplished. To prevent possible rotor failure with consequent engine damage, accomplish the following: (a) Before further flight, except that the helicopter may be flown in accordance with FAR Sections 21.197 and 21.199 to a base where the work can be performed, accomplish the following: (1) Install an operating limitation placard on the instrument panel in full view of the pilot, setting forth the following limitation: "DO NOT OPERATE ROTOR BRAKE." (2) Inspect the main rotor brake saddle Goodrich P/N 2-1188, for loose or detached brake blocks, Goodrich P/N 27-516. (b) If, during the inspection required by paragraph (a)(2) of this AD a loose brake block is found, before further flight, remove the main rotor brake saddle in accordance with the procedures contained in paragraph (c)(2) of this AD. (c) If, during the inspection required by paragraph (a)(2) of this AD a brake block is found detached, before further flight, accomplish the following: (1) Inspect the main gearbox compartment for the brake block or brake block debris. If the entire brake block is not recovered, inspect the compressor section of each engine for foreign object damage, and repair, as necessary, in accordance with the Allison Maintenance and Overhaul Manual for the Model 250 engine. (2) Remove the main rotor brake saddle as follows: (i) Detach pressure hose, P/N 105-10610, at rotor brake saddle. (ii) Operate brake lever until flow of fluid from detached hoses ceases. (iii) Detach hose, P/N 105-10610, from pressure relief valve, P/N 105-10511. (iv) Seal outlet of pressure relief valve, P/N 105-10511, with non- metallic blind plug or with tape. (v) Remove bolts attaching main rotor brake saddle to main gearbox. (vi) Remove main rotor brake saddle. (d) If, during the inspection required by paragraph (a)(2) of this AD, the brake block is found not to be loose or detached, within the next 10 hour time in service after the effective date of this AD, remove the brake block saddle in accordance with the procedures contained in paragraph (c)(2) of this AD. (e) The operating limitations placard required by paragraph (a) of this AD, may be removed upon the installation of an improved main rotor brake saddle, Goodrich P/N 2-1188-J. NOTE: The helicopter is approved for operation without the main rotor brake saddle. This amendment becomes effective January 6, 1977.