Airworthiness Directive · Amendment 39-14739 · MD Helicopters, Inc. Model MD900 Helicopters
MD Helicopters, Inc. Model MD900 Helicopters
Model MD900 helicopters, with a Notar fan system that has a tension-torsion (TT) strap, part number (P/N) 900R3442009-103, 900R6442009-103, 900R3442009-101, or 500N5311-5, installed, certificated in any category.
This amendment supersedes an existing airworthiness directive (AD) for MD Helicopters, Inc. (MDHI) Model MD900 helicopters, that currently requires reducing the life limit of certain Notar fan system tension-torsion (TT) straps. That existing AD also requires, at a specified time interval, removing each affected TT strap from the helicopter, doing a visual and X-ray inspection, and replacing any unairworthy part before further flight. This amendment requires the same actions as the existing AD, but also requires revising the life limit on the component history card or equivalent record and doing repetitive visual and X-ray inspections, and removes reporting requirements. This amendment is prompted by two in-flight TT strap failures. The actions specified by this AD are intended to prevent failure of a TT strap, loss of directional control, and subsequent loss of control of the helicopter.
To prevent failure of a TT strap in the Notar fan system, loss of directional control, and subsequent loss of control of the helicopter, accomplish the following:
(a) Before further flight, unless accomplished previously, for TT Straps, P/N 900R3442009-103 and 900R6442009-103, reduce the life limit from 3,034 to 2,500 hours time-in-service (TIS) and revise the life limit on the component history card or equivalent record to reflect this reduced retirement life.
(b) Within 10 hours TIS, unless accomplished previously, for any TT strap that has accumulated 1,190 or more hours TIS, and then at intervals not to exceed 300 hours TIS, remove the TT strap from the helicopter and do a visual and an X-ray inspection in accordance with the Inspection Instructions, paragraph 2.B.(1). through (5)., and Figures 1 and 2 of MD Helicopters Service Bulletin SB900-095, dated November 3, 2004 (SB). Replace any unairworthy TT strap before further flight.
(c) Before the TT strap accumulates 1,200 hours TIS, for any TT strap with less than 1,190 hours TIS, and then at intervals not to exceed 300 hours TIS, remove the TT strap from the helicopter and do a visual and an X-ray inspection in accordance with the Inspection Instructions, paragraph 2.B.(1). through (5)., and Figures 1 and 2 of the SB. Replace any unairworthy TT strap before further flight.
(d) The X-ray inspection of the TT strap must be performed by a Level II or higher X-ray technician who is qualified under the guidelines established by MIL-STD-410E, ATA Specification 105, AIA-NAS-410, or an FAA-accepted equivalent for qualification standards.
(e) This AD revises the Airworthiness Limitations section of the maintenance manual by reducing the life limit of the TT straps, P/N 900R3442009-103 and 900R6442009-103, from 3,034 hours TIS to 2,500 hours TIS. Additionally, this AD revises the Airworthiness Limitations section of the maintenance manual by adding repetitive inspection requirements at intervals not to exceed 300 hours TIS for TT straps, P/N 900R3442009-103, 900R6442009-103, 900R3442009-101, and 500N5311-5, that have 1,200 or more hours TIS until the TT strap reaches its retirement life.
(f) 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, FAA, ATTN: Roger Durbin, Aviation Safety Engineer, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5233, fax (562) 627-5210, for information about previously approved alternative methods of compliance.
(g) The X-ray inspection shall be done in accordance with the specified portions of MD Helicopters Service Bulletin SB900-095, dated November 3, 2004. The incorporation by reference of that document was approved previously by the Director of the Federal Register, in accordance with 5 U. S.C. 552(a) and 1 CFR part 51, as of December 7, 2004 (69 FR 67806, November 22, 2004). Copies may be obtained from MD Helicopters Inc., Attn: Customer Support Division, 4555 E. McDowell Rd., Mail Stop M615, Mesa, Arizona 85215-9734, telephone 1-800-388-3378, fax 480-346-6813, or on the web at http://www.mdhelicopters.com. Copies may be inspected at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
