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Airworthiness Directives; MD Helicopters, Inc. Model 369D, 369E, 369F, and 369FF Helicopters

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Federal Aviation Administration, DOT.


Final rule.


This amendment revises an airworthiness directive (AD) for the specified MD Helicopters, Inc. (MDHI) helicopters that currently requires identifying the part number (P/N) of the bolts that attach the tail rotor gearbox to the tailboom and replacing any bolt of inadequate grip length with an airworthy bolt. That AD also requires adding an additional washer if more than four threads protrude from the nutplate. This amendment requires the same actions as the existing AD but reduces the applicability to only certain tailboom serial numbers and parts modified in accordance with either Supplemental Type Certificate (STC) SH5055NM or SH4801NM. This amendment also corrects a typographical error and clarifies that a slippage mark needs to be reapplied to each bolt regardless of the outcome of the required torque test. This amendment is prompted by the need to correct and clarify the applicability and other portions of the existing AD. The actions specified by this AD are intended to prevent loss of a tail rotor gearbox due to bolts of inadequate grip length and subsequent loss of control of the helicopter.


Effective February 25, 2003.

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John Cecil, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712-4137, telephone (562) 627-5228, fax (562) 627-5210.

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A proposal to amend 14 CFR part 39 by revising AD 2002-13-05, Amendment 39-12793 (67 FR 43227, June 27, 2002), for the specified MDHI model helicopters with a tailboom modified according to either Aerometals STC SH5055NM or SH4801NM, was published in the Federal Register on September 24, 2002 (67 FR 185).

Before issuing AD 2002-13-05, the FAA solicited comments by a Notice of Proposed Rulemaking, published in the Federal Register on December 27, 2001 (66 FR 66821). A commenter stated that the applicability of the AD should be limited to certain part-numbered tailbooms with serial number (S/N) 5001-5032 specified in the FAA-approved Aerometals service bulletin. We did not agree with the commenter and, except for minor editorial changes, issued the AD as proposed (67 FR 43227, June 27, 2002). Since issuing AD 2002-13-05, we have determined that we inappropriately responded to the comment and that the commenter's concern was valid. We are now reducing the applicability of AD 2002-13-05 to include only certain tailboom S/N's and parts that are modified in accordance with either STC SH5055NM or SH4801NM. We are also correcting the P/N for the washer to P/N AN960D416 in Figure 1 of this AD and clarifying that a slippage mark needs to be reapplied to each bolt regardless of the outcome of the required torque test.

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.

The FAA estimates that this AD will affect 500 helicopters of U.S. registry. Also, the FAA estimates this AD will require 1/2 work hour per helicopter to determine whether a helicopter has been modified by either STC and 1 work hour to inspect and replace the bolts for each of approximately 40 helicopters modified by the STC's. The average labor rate is $60 per work hour. Required parts will cost approximately $40 per helicopter. Based on these figures, we estimate the total cost impact of the AD on U.S. operators to be $19,000.

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 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
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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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2. Section 39.13 is amended by removing Amendment 39-12793 ( 67 FR 43227, June 27, 2002), and by adding a new airworthiness directive to read as follows:

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2002-13-05 R1 MD Helicopters, Inc.:\1/2\ Amendment 39-13022, Docket No. 2001-SW-40-AD. Revises AD 2002-13-05, Amendment 39-12793.

Applicability: The following MD Helicopters, Inc. helicopter models, certificated in any category:

Helicopter modelWithModified In accordance with
(1) 369D, 369E, 369F, 369FFTailboom, serial number (S/N) 5001-5032Aerometals Supplemental Type Certificate (STC) SH5055NM
(2) 369D and 369ETail Rotor Gearbox Attach BoltsAerometals STC SH4801NM

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 as indicated, unless accomplished previously.

To prevent loss of the tail rotor gearbox due to attaching bolts of inadequate grip length and subsequent loss of control of the helicopter, accomplish the following:

(a) Within 25 hours time-in-service (TIS):

(1) For each tail rotor gearbox attaching bolt (bolt):

(i) Determine the part number (P/N).

(ii) If the P/N cannot be determined or if the bolt is not P/N NAS1304-26, before further flight, replace the bolt with bolt, P/N NAS1304-26.

(iii) Torque the bolt to 100-110 in-lbs and apply a slippage mark.

(2) Remove the tailboom control rod and determine the number of bolt threads protruding from each nutplate on the internal surface of the aft tailboom frame casting, P/N 369D23503, as shown in Figure 1 of this AD. At least one thread must protrude. If more than four threads protrude, add an additional washer, P/N AN960D416, under the bolt head. Torque the bolt to 100-110 in-lbs, and reapply a slippage mark. See Figure 1:

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(b) Between 2 and 10 hours TIS after accomplishing the requirements of paragraph (a) of this AD, inspect the torque on each bolt by applying 100 in-lbs. If any bolt movement occurs, retorque the bolt to 100-110 in-lbs. Reapply a slippage mark to the bolt regardless of the outcome of the torque test. Reinspect the torque between 2 and 10 hours TIS thereafter until no bolt movement occurs.

Note 2:

Aerometals Service Bulletin SB-001, dated August 3, 2000, pertains to the subject of this AD.

(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 3:

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 will not be issued.

(e) This amendment becomes effective on February 25, 2003.

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Issued in Fort Worth, Texas, on January 11, 2003.

David A. Downey,

Manager, Rotorcraft Directorate, Aircraft Certification Service.

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[FR Doc. 03-1189 Filed 1-17-03; 8:45 am]