79-24-06 MESSERSCHMITT-BOLKOW-BLOHM GmbH: Amendment 39-3622. Applies to all Model BO-105 helicopters, certificated in any category, incorporating tail rotor blades P/N 105-31742 or P/N 105-87161 that have not been modified in accordance with the Accomplishment Instructions, paragraph 2.B., of Messerschmitt-Bolkow-Blohm Alert Service Bulletin No. AB-16, Revision 1, dated December 22, 1978, hereinafter referred to as the Service Bulletin, or an FAA-approved equivalent.
Compliance required as indicated.
To prevent in-flight loss of tail rotor balance trim weights, and consequent imbalance of the tail rotor blades, accomplished the following:
(a) Within the next 10 hours time in service after the effective date of this AD, and thereafter following the last flight of each day upon which the accumulated time in service since the preceding inspection reaches 10 hours, until the modifications required by paragraph (c) of this AD are accomplished, inspect the tail rotor blades for condition in accordance with paragraph 2.A. of the Accomplishment Instructions of the Service Bulletin, or an FAA-approved equivalent.
(b) If the inspection required by paragraph (a) of this AD reveals any cracks, or bonding separation that is unacceptable in accordance with the inspection criteria contained in paragraph 2.A. of the Service Bulletin, or an FAA-approved equivalent, before further flight, except that the helicopter may be flown in accordance with FAR 21.197 to a place where the required work can be performed -
(1) Replace the affected blade with a serviceable blade of the same part number and continue to comply with the repetitive inspection and modification requirements of paragraph (a) and (c) of this AD; or
(2) Replace both blades with blades of improved design, P/N 105-31743 or P/N 105-31744 after which paragraphs (a) and (c) of this AD do not apply. (See paragraph (d) of this AD.)
(c) Within the next 100 hours time in service after the effective date ofthis AD, inspect the tail rotor blades in accordance with paragraph 2.A. of the Service Bulletin or an FAA-approved equivalent and before further flight -
(1) If the inspection reveals any cracks, or bonding separation that is not acceptable in accordance with the inspection criteria contained in paragraph 2.A. of the Service Bulletin or an FAA-approved equivalent -
(i) Replace the affected blade with a serviceable blade of the same part number and modify the tail rotor blade balance provisions of both blades in accordance with paragraph 2.B. of Accomplishment Instructions of the Service Bulletin or an FAA-approved equivalent; or
(ii) Replace both blades with blades of improved design, P/N 105-31743 or P/N 105- 31744. (See paragraph (d) of this AD.)
(2) If the inspection does not reveal any cracks or bonding separation that is not acceptable in accordance with the inspection criteria contained in paragraph 2.A. of the Service Bulletin or an FAA-approved equivalent, modify the tail rotor blade balance provisions of both blades in accordance with paragraph 2.B. of the Service Bulletin or an FAA-approved equivalent.
(d) If tail rotor blades are to be changed in compliance with this AD, both blades must be of the same part number.
(e) For the purpose of this AD, an FAA-approved equivalent must be approved by the Chief, Aircraft Certification Staff, AEU-100, FAA, Europe, Africa, and Middle East Region, c/o American Embassy, Brussels, Belgium.
This amendment becomes effective December 10, 1979.