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. 2004-SW-16-AD.” The postcard will be date stamped and returned to the commenter.

Discussion

On November 28, 2001, the FAA issued Emergency AD 2001-24-51 for MDHI Model 600N helicopters and issued the final rule; request for comments on April 2, 2002 (Amendment 39-12706 (67 FR 17934, April 12, 2002)). That AD requires implementing the procedures described in MD Helicopters, Inc. Service Bulletin SB600N-03, dated November 2, 2001 (SB600N-03), for inspecting both upper tailboom attachments, nutplates, and angles for a crack or thread damage and repairing or replacing damaged parts. In addition, if one bolt is broken, the AD requires replacing all four bolts. Also, adding a washer to each bolt and modifying both upper access covers as well as a 25-hour time-in-service (TIS) repetitive borescope inspection of the tailboom attachments, nutplates, and angles is required. That action was prompted by the discovery of cracked bolts and attachments on several helicopters. The requirements of that AD are intended to prevent failure of a tailboom attachment, loss of the tailboom, and subsequent loss of control of the helicopter.

Since issuing that AD, the FAA has reviewed an analysis by the manufacturer and has determined that the tailboom fittings, part number (P/N) 500N3422-BSC (BSC is interchangeable with basic) and -3, and the upper longerons, P/N 500N3120-3 and -4, will develop cracks due to the same design error as the current AD. Also, the FAA has reviewed MDHI Service Bulletin SB600N-039, dated December 9, 2003, which provides information pertaining to adding six inspection holes in the fuselage and certain inspections of the tailboom attachment fittings and upper longerons for cracks. Also, MDHI has issued Technical Bulletin TB 600N-007, dated January 12, 2004, which provides information pertaining to modifying the fuselage aft section to strengthen tailboom attachment fittings and longerons.

This previously described unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, the proposed AD would supersede AD 2001-24-51 to require the following:

• Before further flight, drill an inspection hole at fuselage station L167 and R167 (L indicates Left and R indicates Right) on each side of the fuselage.
• Within 25 hours time-in-service (TIS):
• Drill two additional inspection holes on each side of the fuselage at L166, R166, L153, and R153.
• Visually inspect the lower attachment fittings and the upper longerons through inspection holes at L166, R166, L153 and R153, respectively.
• Thereafter, at specified intervals, remove the plug buttons from the inspection holes at L167, R167, L166, ( printed page 7064) and R166. Using a bright light, inspect the attachment fittings, angles, and nutplates for a crack. Through inspection holes L153 and R153, using a bright light and mirror or borescope, visually inspect the bottom surface of each longeron for a crack.
• Before further flight, replace any cracked attachment fitting, angle, nutplate, longeron, and any nutplate with thread damage with an appropriate airworthy part.

This action proposes to require that operators modify the aft fuselage to strengthen the tailboom attachments and longeron within 4 years, which would constitute terminating action for the requirements of the AD.

The FAA estimates that this proposed AD would affect 39 helicopters of U.S. registry. The proposed actions would take about 322 work hours to modify and inspect the fuselage aft section per helicopter at an average labor rate of $65 per work hour. Required parts would cost approximately $14,960 per helicopter. Based on these figures, we estimate the total cost impact of the proposed AD on U.S. operators to be $1,399,710.

Regulatory Findings

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 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.

Authority for this Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

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: