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Airworthiness Directives; MD Helicopters, Inc., Model 600N Helicopters

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Start Preamble Start Printed Page 51149


Federal Aviation Administration, DOT.


Final rule.


This amendment adopts a new airworthiness directive (AD) for the specified MD Helicopters, Inc. (MDHI) model helicopters that requires reducing the life limit of the main rotor drive shaft (drive shaft) and changing the life limit on the component history card or equivalent record. This amendment is prompted by the review of final fatigue test data, which indicates that the life limit of the drive shaft should be reduced by 2000 hours time-in-service (TIS). The actions specified by this AD are intended to prevent failure of the drive shaft, loss of drive of the main rotor system, and subsequent loss of control of the helicopter.


Effective September 30, 2003.

Start Further Info


Chinh Vuong, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, Propulsion Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5264, fax (562) 627-5210.

End Further Info End Preamble Start Supplemental Information


A proposal to amend 14 CFR part 39 to include an AD for the specified model helicopters was published in the Federal Register on May 19, 2003 (68 FR 27006). That action proposed reducing the life limit of the drive shaft from 16,000 hours TIS to 14,000 hours TIS and revising the component history card or an equivalent record to reflect the reduced life limit.

MDHI has issued Service Bulletin SB600N-033, dated December 13, 2001, which specifies reducing the life limit of the drive shaft at the next scheduled maintenance or within 1 year, whichever occurs first.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public. The FAA has determined that air safety and the public interest require the adoption of the rule as proposed.

On July 10, 2002, the FAA issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's AD system. The regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. However, for clarity and consistency in this final rule, we have retained the language of the NPRM regarding that material.

The FAA estimates that this AD will affect 46 helicopters of U.S. registry, and it will take approximately .5 work hour per helicopter to update the records at an average labor rate of $65 per work hour. Based on these figures, we estimate the total cost impact of the AD on U.S. operators to be $1,495.

The regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas.

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List of Subjects in 14 CFR Part 39

  • Air transportation
  • Aircraft
  • Aviation safety
  • Safety
End List of Subjects

Adoption of the Amendment

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Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

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1. The authority citation for part 39 continues to read as follows:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

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Start Amendment Part

2. Section 39.13 is amended by adding a new airworthiness directive to read as follows:

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2003-16-11 MD Helicopters, Inc.: Amendment 39-13264. Docket No. 2003-SW-04-AD.

Applicability: Model 600N, with main rotor drive shaft assembly (drive shaft), part number (P/N) 600N5510-1, installed, certificated in any category.

Note 1:

This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required within 100 hours time-in-service (TIS), unless accomplished previously.

To prevent failure of the drive shaft, loss of drive to the main rotor hub, and subsequent loss of control of the helicopter, accomplish the following:

(a) Revise the component history card or equivalent record for drive shaft, P/N 600N5510-1, by changing the life limit from 16,000 to 14,000 hours TIS. Before further flight, replace any drive shaft that has 14,000 or more hours TIS with an airworthy drive shaft. Start Printed Page 51150

(b) This AD revises the Limitations section of the maintenance manual by reducing the life limit of the drive shaft, P/N 600N5510-1, to 14,000 hours TIS.

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Los Angeles Aircraft Certification Office (LAACO), FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, LAACO.

Note 2:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the LAACO.

(d) Special flight permits may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the helicopter to a location where the requirements of this AD can be accomplished.

(e) This amendment becomes effective on September 30, 2003.

Start Signature

Issued in Fort Worth, Texas, on August 5, 2003.

David A. Downey,

Manager, Rotorcraft Directorate, Aircraft Certification Service.

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[FR Doc. 03-21521 Filed 8-25-03; 8:45 am]