Airworthiness Directive · Amendment 39-15030 · MD Helicopters Inc. (MDHI) Model MD600N Helicopters
MD Helicopters Inc. (MDHI) Model MD600N Helicopters
Model MD600N helicopters, with a lateral mixer output link assembly (mixer link), part number (P/N) 600N7636-1, -3, -9, or -11 installed, certificated in any category.
This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 2007-05-51, which was sent previously to all known U.S. owners and operators of MDHI Model MD600N helicopters by individual letters. This AD requires, before further flight, a visual and eddy current inspection of each lateral mixer output link assembly (mixer link) and replacing any cracked mixer link. This AD also requires performing an eddy current inspection on each mixer link before installing it on any helicopter. This amendment is prompted by the discovery of 3 cracked mixer links. The actions specified by this AD are intended to detect a crack in the mixer link, which could result in failure of the mixer link and subsequent loss of control of the helicopter.
To detect a crack in the mixer link, which could result in failure of the mixer link and subsequent loss of control of the helicopter, accomplish the following:
(a) Before further flight:
(1) Remove each mixer link and visually inspect, with a bright light and a 10x or higher magnifying glass, the shaded areas around the bearing bore for any crack as depicted in the following Figure 1:
(2) Perform an eddy current inspection of each mixer link in the bearing end areas.
(3) Replace any cracked mixer link with an airworthy mixer link on which an eddy current inspection has been performed.
Note: MDHI Service Bulletin No. SB600N-044, dated February 16, 2007, pertains to the subject of this AD.
(b) Perform an eddy current inspection on each mixer link before installing it on any helicopter.
(c) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Contact the Manager, Los Angeles Aircraft Certification Office, FAA, ATTN: Jon Mowery, Aviation Safety Engineer, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5322, fax (562) 627-5210, for information about previously approved alternative methods of compliance.
(d) A one-time special flight permit may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the helicopter to a location where the eddy current inspection requirements of this AD can be accomplished provided that no crack is found during the visual inspection required in paragraph (a) of this AD and that the helicopter's airspeed does not exceed 100 knots.
