AD 2013-03-03 Airworthiness Directives; MD Helicopters, Inc., Helicopters

This AD becomes effective March 15, 2013.

(1) The Manager, Los Angeles Aircraft Certification Office, FAA, may approve AMOCs for this AD. Send your proposal to: John Cecil, Aviation Safety Engineer, Los Angeles Aircraft Certification Office, Transport Airplane Directorate, FAA, 3960 Paramount Blvd., Lakewood, California 90712; telephone (562) 627-5228; email john.cecil@faa.gov. (2) For operations conducted under a 14 CFR part 119 operating certificate or under 14 CFR part 91, subpart K, we suggest that you notify your principal inspector, or lacking a principal inspector, the manager of the local flight standards district office or certificate holding district office before operating any aircraft complying with this AD through an AMOC.

MDHI has issued one service bulletin with two numbers, SB500N-029R3 for the Model 500N helicopters, and SB600N-046R3 for the Model 600N helicopters, dated July 9, 2008. MDHI has also issued SB900-107R1, dated March 14, 2008, for the Model MD900 helicopters. These service bulletins, which are not incorporated by reference, contain information related to the subject of this AD. For service information identified in this AD, contact 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. You may review a copy of this service information at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137.

(1) Within six months, determine the manufacturer's cure date of each of the 13 T-T straps. (i) For a T-T strap with five or more calendar years from the manufacturer's cure date, before further flight, replace the T-T strap with an airworthy T-T strap. (ii) For a T-T strap with less than five calendar years from the manufacturer's cure date, mark the expiration date on the T-T strap face in permanent ink. (2) Thereafter, before installing a T-T strap, mark the expiration date on the T-T strap using permanent ink. The expiration date is five years from the date the T-T strap package was opened, or if that date was not recorded, five years from the manufacturer's cure date. (3) On or before the date you comply with paragraph (e)(1) or (e)(2) of this AD, create a component record card for each T-T strap and record on the card the manufacturer's cure date or the date that the T-T strap package was opened, if that date was recorded previously, and the T-T strap expiration date. (4) Revise the Airworthiness Limitations section of the maintenance manual by establishing: (i) A calendar life limit for the T-T straps, P/N 500N5311-5, 900R3442009-101, 900R3442009-103, and 900R6442009-103 of five years from the date the T-T strap package was opened, or if that date was not recorded, five years from the manufacturer's cure date. (ii) A 2,500 hour time-in-service (TIS) life limit for any T-T straps, P/N 500N5311-5, installed on a Model 500N or Model 600N helicopter that was previously installed on a Model MD900 helicopter. Note to paragraph (e) of this AD: For the MDHI Model MD900 helicopters, AD 2006-18-01 (71 FR 51095, August 29, 2006) contains additional TIS life limits for T-T straps, P/N 900R3442009-103 and P/N 900R6442009-103 and additional inspection requirements for all four affected T-T straps, P/N 500N5311-5, P/N 900R3442009-101, P/N 900R3442009-103, and P/N 900R6442009-103.

This AD defines the unsafe condition as a decrease, over time, in the strength of a T-T strap caused by moisture. This condition could result in failure of a T-T strap, loss of directional control, and subsequent loss of control of the helicopter.