03-12401. 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 MD Helicopters Inc. Model 600N helicopters. The AD would require reducing the life limit of the main rotor drive shaft (drive shaft) and changing the life limit shown on the component history card or equivalent record. This proposal 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 the proposed AD are intended to prevent failure of the drive shaft, loss of drive to the main rotor system, and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before July 18, 2003.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional Counsel, Southwest Region, Attention: Rules Docket No. 2003-SW-04-AD, 2601 Meacham Blvd., Room 663, Fort Worth, Texas 76137. You may also send comments electronically to the Rules Docket at the following address: [e-mail]. 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:

Guy Dalla Riva, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, Propulsion Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone [phone], fax [phone].

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-04-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 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. This proposal is prompted by the review of final fatigue test data, which indicates that the life limit of the drive shaft should be reduced to prevent parts from remaining in service beyond their fatigue life. This condition, if not corrected, could result in failure of the drive shaft, loss of drive to the main rotor system, and subsequent loss of control of the helicopter.

The FAA has reviewed MD Helicopters Inc. Service Bulletin SB600N-033, dated December 13, 2001 (ASB), which specifies reducing the life limit of the drive shaft at the next scheduled maintenance or within 1 year, whichever occurs first.

This unsafe condition created by this reduced fatigue life limit to a critical component is likely to exist or develop on other helicopters of the same type design. Therefore, the proposed AD would require within 100 hours TIS reducing the life limit for the drive shaft from 16,000 hours TIS to 14,000 hours TIS and reflecting the reduced life limit on the component history card or an equivalent record.

The FAA estimates that this proposed AD would affect 46 helicopters of U.S. registry, that it would take approximately .5 work hour per helicopter to update the records, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $1,380.

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 draft regulatory 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.

§ 39.13

[Amended]

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

MD Helicopters Inc.: 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.

(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.

Issued in Fort Worth, Texas, on May 12, 2003.

David A. Downey,

Manager, Rotorcraft Directorate, Aircraft Certification Service.