04-24228. Airworthiness Directives; MD Helicopters, Inc. Model 600N Helicopters

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Final rule.

SUMMARY:

This amendment adopts a new airworthiness directive (AD) for MD Helicopters, Inc. Model 600N helicopters that requires replacing the fuselage Station 75 control support bracket assembly (control support bracket), reducing the life limit, and revising the Limitations section of the applicable maintenance manual to state the reduced life limits on certain serial-numbered helicopters. This amendment is prompted by information received from the manufacturer indicating that the fatigue life of the control support bracket is shorter than the original analysis indicated. The actions specified by this AD are intended to prevent failure of the control support bracket and subsequent loss of control of the helicopter.

DATES:

Effective December 3, 2004.

FOR FURTHER INFORMATION CONTACT:

Fred Guerin, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone [phone], fax [phone].

SUPPLEMENTARY 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 July 29, 2004 (69 FR 45291). That action proposed to require replacing the control support bracket assembly, part number (P/N) 369N2608-11, on helicopters that have a yaw stability augmentation system (YSAS) installed, with an airworthy assembly, P/N 600N2608-1. The revised time limits are dependent upon the time the YSAS was initially installed. Also proposed was revising the applicable maintenance manual to state the reduced life limits.

The FAA has reviewed MD Helicopters, Inc. Service Bulletin No. SB600N-040, dated September 18, 2003, which describes the revised finite life for the control support bracket on certain serial-numbered helicopters, and replacing them upon reaching the revised life limit, or no later than November 30, 2005, 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.

The FAA estimates that this AD will affect 13 helicopters of U.S. registry. Replacing the control support bracket will take approximately 40 work hours per helicopter to accomplish at an average labor rate of $65 per work hour. Required parts will cost approximately $5,617 per helicopter. Based on these figures, the total estimated cost impact of this AD on U.S. operators is $106,821 to replace the control support bracket on each helicopter in the fleet.

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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

Adoption of the Amendment

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:

PART 39—AIRWORTHINESS DIRECTIVES

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

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

§ 39.13

[Amended]

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

2004-22-12 MD Helicopters, Inc.: Amendment 39-13840. Docket No. 2003-SW-51-AD.

Applicability: Model 600N helicopters, serial numbers with a prefix of “RN” and numbers 025, 029, 032, 034 through 038, 040, 041, 045, 048, or 067; or, any Model 600N helicopter with a yaw stability augmentation system (YSAS) installed, and with a control support bracket assembly, part number (P/N) 369N2608-11, installed, certificated in any category.

Compliance: Required as indicated, unless accomplished previously.

To prevent failure of the fuselage Station 75 control support bracket assembly (control support bracket) and subsequent loss of control of the helicopter, accomplish the following:

(a) Replace the control support bracket, part number 369N2608-11, with an airworthy control support bracket assembly, P/N 600N2608-1, no later than November 30, 2005, or by the time the helicopter reaches the hours time-in-service (TIS) listed in the chart below, whichever occurs first:

Helicopter serial number	Revised finite life (TIS)
RN025	2556
RN029	2377
RN032	2498
RN034	2456
RN035	2243
RN036	2652
RN037	2544
RN038	2531
RN040	2562
RN041	2763
RN045	2015
RN048	2125
RN067	1600

Note:

MD Helicopters, Inc. Service Bulletin No. SB600N-040, dated September 18, 2003, pertains to the subject of this AD.

(b) For helicopters with a YSAS installed that are not listed in the previous table, replace the control support bracket, P/N 369N2608-11, with an airworthy control support bracket, P/N 600N2608-1, no later than November 30, 2005, or by the time the helicopter reaches 1,600 hours TIS since the installation of the YSAS.

(c) For helicopters with no YSAS installed, but with a control support bracket, P/N 369N26080-11, installed, replace the control support bracket, with an airworthy control support bracket, P/N 600N2608-1, prior to the installation of a YSAS.

(d) This AD revises the Limitations section of the applicable maintenance manual by reducing the life limit of the control support bracket assembly, part number 369N2608-11, to the life limits stated in paragraph (a) of this AD or to 1,600 hours TIS, whichever occurs first.

(e) 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 Los Angeles Aircraft Certification Office, Transport Airplane Directorate, FAA, for information about previously approved alternative methods of compliance.

(f) This amendment becomes effective on December 3, 2004.

Issued in Fort Worth, Texas, on October 22, 2004.

David A. Downey,

Manager, Rotorcraft Directorate, Aircraft Certification Service.