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

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes adopting a new airworthiness directive (AD) for the MD Helicopters, Inc. Model 600N helicopters. The AD would require 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 proposal 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 the proposed AD are intended to prevent failure of the control support bracket and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before September 27, 2004.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2003-SW-51-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. You may also send comments electronically to the Rules Docket at the following address: 9-asw-adcomments@faa.gov. Comments may be inspected at the Office of the Regional Counsel between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Fred Guerin, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5232, fax (562) 627-5210.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments will be considered before taking action on the proposed rule. The proposals contained in this document may be changed in light of the comments received.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their mailed comments submitted in response to this proposal must submit a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. 2003-SW-51-AD.” The postcard will be date stamped and returned to the commenter.

Discussion

This document proposes adopting a new AD for MD Helicopters, Inc. Model 600N helicopters. The AD would 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. Revising the applicable maintenance manual to state the reduced life limits would also be required. This proposal 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 for those models in which a YSAS is installed. The actions specified by the proposed AD are intended to prevent failure of the control support bracket and subsequent loss of control of the helicopter.

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 requiring replacing them upon reaching the revised life limit, or no later than November 30, 2005, whichever occurs first.

This unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, the proposed AD would require replacing the control support bracket before it reaches a certain number of hours time-in-service, or no later than November 30, 2005, whichever occurs first.

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

The regulations proposed herein would 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 proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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 copy of the economic evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 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.