AD 81-03-01

81-03-01 MESSERSCHMITT-BOLKOW-BLOHM GMBH: Amendment 39-4033. Applies to Model BO-105 series helicopters, certificated in all categories.

Compliance required as indicated, unless already accomplished.

To prevent failure of the helicopter drive system, accomplish the following:

(a) Within the next 10 hours time in service after the effective date of this AD, for all installed Bendix drive shafts, P/N 19E146-1 (all modification indices), hereinafter referred to as drive shaft, inspect all nutplates for selflocking capability in accordance with Action No. 1 of paragraph 2B, "ACCOMPLISHMENT INSTRUCTIONS," of Messerschmitt-Bolkow-Blohm GmbH Alert Service Bulletin AB-19, dated March 7, 1980 (hereinafter referred to as the service bulletin), or an FAA-approved equivalent.

(b) If as a result of the inspection required in paragraph (a) of this AD, all selflocking nutplates are found to have the proper selflocking capability -

(1) Identify the drive shaft in accordance with Action No. 1, Item (6) of paragraph 2B, "ACCOMPLISHMENT INSTRUCTIONS," of the service bulletin, or an FAA- approved equivalent; and

(2) Return the drive shaft to service in accordance with Action No. 1, Item (6), and Action No. 2 of paragraph 2B, "ACCOMPLISHMENT INSTRUCTIONS," of the service bulletin, or an FAA-approved equivalent.

(c) If as a result of the inspection required in paragraph (a) of this AD, one or more selflocking nutplates are found to be defective, before further flight -

(1) Remove the drive shaft from service and replace the defective shaft with a serviceable or new shaft which has new selflocking nutplates, P/N LN 29679AM9 installed, or have been marked with a blue dot, in accordance with Action No. 3 of paragraph 2B, "ACCOMPLISHMENT INSTRUCTIONS," of the service bulletin, or an FAA-approved equivalent; or

(2) Comply with paragraph (d) of this AD.

(d) If as a result of the inspection required in paragraph (a) of this AD on an installed drive shaft, one or more nutplates are found to have inadequate selflocking capability, the helicopter may be continued in service provided -

(1) Drive shaft tab washers, P/N LN 9023-B8-1.4544.9, are installed in lieu of the standard washer in accordance with Action No. 4 of paragraph 2B, "ACCOMPLISHMENT INSTRUCTIONS," of the service bulletin, or an FAA-approved equivalent; and

(2) Paragraph (c)(2) of this AD must be accomplished before the accumulation of an additional 300 hours time in service.

(e) For all drive shafts held as spares, before release to service, inspect the selflocking nutplate for proper selflocking capability in accordance with Action No. 2 of paragraph 2B, "ACCOMPLISHMENT INSTRUCTIONS," of the service Bulletin, or an FAA- approved equivalent.

(f) Helicopters may be flown in accordance with FAR Sections 21.197 and 21.199 to a base where the inspections and repairs required by this AD may be performed.

(g) If an equivalent means of compliance is used in complying with this AD, that equivalent must be approved by the Chief, Aircraft Certification Staff, Europe, Africa and Middle East Office, c/o American Embassy, Brussels, Belgium.

(h) Report defects found to the Chief, Aircraft Certification Staff, Europe, Africa, and Middle East Office, c/o American Embassy, Brussels, Belgium. (Reporting approved by Office of Management and Budget under OMB No. 04-R0174.)

NOTE: Messerschmitt-Bolkow-Blohm Gmbh telegraphic message to all operators, dated March 7, 1980, refers to the same subject.

This amendment becomes effective January 29, 1981, as to all persons except those persons to whom it was immediately effective by telegraphic AD T80EU23, issued May 8, 1980, which contained this amendment.