E7-20680. Airworthiness Directives; MD Helicopters, Inc. Model 600N Helicopters

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes superseding an existing airworthiness directive (AD) for MD Helicopters, Inc. (MDHI) Model 600N helicopters. That AD currently requires interim initial and repetitive inspections of tailboom parts, installing six inspection holes in the aft fuselage skin panels, installing tailboom attachment bolt washers, modifying both access covers, and replacing broken attachment bolts. The current AD also provides for modifying the fuselage aft section as an optional terminating action. This proposal would mandate modifying the fuselage aft section within the next 24 months to strengthen the tailboom attachment fittings and upper longerons. The actions specified by the proposed AD are intended to prevent failure of the tailboom attachment fittings, separation of the tailboom from the helicopter, and subsequent loss of control of the helicopter.

DATES:

Comments must be received on or before December 18, 2007.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

You may get the service information identified in this proposed AD from MD Helicopters Inc., Attn: Customer Support Division, 4555 E. McDowell Rd., Mail Stop M615, Mesa, Arizona 85215-9734, telephone [phone], fax [phone], or on the web at www.mdhelicopters.com.

You may examine the comments to this proposed AD in the AD docket on the Internet at http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT:

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

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any written data, views, or arguments regarding this proposed AD. Send your comments to the address listed under the caption ADDRESSES. Include the docket number “FAA-2007-29342, Directorate Identifier 2007-SW-08-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed rulemaking. Using the search function of our docket Web site, you can find and read the comments to any of our dockets, including the name of the individual who sent or signed the comment. You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://www.regulations.gov.

Examining the Docket

You may examine the docket that contains the proposed AD, any comments, and other information in person at the Docket Operations Office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Operations office (telephone [phone]) is located in Room W12-140 on the ground floor of the West Building at the street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

Discussion

On April 20, 2006, we issued AD 2006-08-12, Amendment 39-14569 (71 FR 24808, April 27, 2006), which superseded AD 2001-24-51, Amendment 39-12706 (67 FR 17934, April 12, 2002). AD 2001-24-51 required inspecting both the upper tailboom attachment fittings, nut plates, and both angles for a crack or thread damage, and repairing or replacing any cracked or damaged part. That AD also required replacing the upper right tailboom attachment bolt with a new bolt. That AD required if the attachment bolt was broken replacing the three remaining attachment bolts with airworthy attachment bolts. Adding a washer to each bolt and modifying both access covers was also required. Thereafter, inspecting the upper tailboom attachments at intervals not to exceed 25 hours time-in-service and repairing or replacing any cracked part was required. Superseding AD 2006-08-12 requires installing six inspection holes in the aft fuselage skin panels, inspecting the tailboom attachment fittings and parts, and replacing or modifying certain parts as necessary. That action was prompted by an accident involving a Model 600N helicopter. The requirements of that AD are intended to prevent failure of the tailboom and subsequent loss of control of the helicopter.

On January 12, 2004, MDHI issued Technical Bulletin (TB) TB600N-007 specifying procedures, tooling, replacement parts, and supplies needed for modifying the fuselage aft section and tailboom. TB600N-007R1, dated April 13, 2006, superseded TB600N-007 to correct some tooling, replacement parts, and supplies. TB600N-007R2, dated October 5, 2006, superseded TB600N-007R1 to correct tooling part numbers and re-sequence some assembly steps. These TBs specify that any aircraft complying with any of these revisions meets the intent of the other TBs.

In AD 2006-08-12, we incorporated by reference TB600N-007R1, dated April 13, 2006. Since issuing that AD, MDHI has issued TB600N-007R2, dated October 5, 2006 (TB), which updates previous issues by further specifying procedures for modifying the fuselage aft section to strengthen the tailboom attachment fittings and upper longerons. This latest revision continues to caution that a high level of sheet metal expertise and experience is required to perform this modification.

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 2006-08-12 to require within the next 24 months, modifying the fuselage aft section to strengthen tailboom attach fittings and upper longerons, which would constitute terminating action for this unsafe condition.

We estimate that this proposed AD would affect 18 helicopters of U.S. registry, and the proposed actions would take about 322 work hours to modify each helicopter at an average labor rate of $80 per work hour. Required parts would cost about $14,960 per helicopter. The manufacturer states in its TB that those complying with the TB within 3 years of the issue date are eligible for special pricing and technical assistance. Based on these figures, we estimate the total cost impact of the proposed AD on U.S. operators to be $732,960, assuming no special pricing from the manufacturer.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. Additionally, this proposed AD 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.

For the reasons discussed above, I certify that the 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. 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.

We prepared a draft economic evaluation of the estimated costs to comply with this proposed AD. See the DMS to examine the draft economic evaluation.

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.

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 removing Amendment 39-14569, AD 2006-08-12, (71 FR 24808, April 27, 2006), and by adding a new airworthiness directive (AD), to read as follows:

MD Helicopter, Inc.: Docket No. FAA-2007-29342, Directorate Identifier 2007-SW-08-AD. Supersedes AD 2006-08-12, Amendment 39-14569, Docket No. FAA-2006-24518, Directorate Identifier 2006-SW-10-AD.

Applicability: Model 600N helicopters, serial numbers with a prefix “RN” and 003 through 058, that have not been modified in the fuselage aft section to strengthen the tailboom attachments and longerons per MD Helicopters (MDHI) Technical Bulletin (TB) TB600N-007, dated January 12, 2004; TB600N-007R1, dated April 13, 2006, or TB600N-007R2, dated October 5, 2006, certificated in any category.

Compliance: Required within the next 24 months, unless accomplished previously.

To prevent failure of the tailboom attachment fittings, separation of the tailboom from the helicopter, and subsequent loss of control of the helicopter, do the following:

(a) Modify the fuselage aft section to strengthen the tailboom attach fittings and upper longerons by following paragraph 2, Accomplishment Instructions, of MDHI TB600N-007R2, dated October 5, 2006, except you are not required to contact the manufacturer. This modification to the fuselage aft section is terminating action for the requirements of this AD.

(b) 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 Manager, Los Angeles Aircraft Certification Office, FAA, ATTN: Jon Mowery, Aviation Safety Engineer, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone [phone], fax [phone], for information about previously approved alternative methods of compliance.

Issued in Fort Worth, Texas, on October 10, 2007.

Scott A. Horn,

Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.