AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

SUMMARY: This document publishes in the Federal Register an amendment adopting Emergency Airworthiness Directive (AD) 2010-18-52 which was sent previously to all known owners and operators of MD Helicopters, Inc. (MDHI) Model MD900 helicopters by individual letters. This AD requires visually inspecting the main rotor hub (hub) for a crack. If a crack is found, this AD requires, before further flight, replacing the unairworthy hub with an airworthy hub. Additionally, if a cracked hub is found, this AD requires reporting the finding to the Los Angeles Aircraft Certification Office within 10 days of finding the crack. This AD is prompted by two reports of cracks detected in the hub in the area near the flex beam bolt hole locations during maintenance on two MDHI Model MD900 helicopters. The actions specified by this AD are intended to detect a crack in the hub and prevent failure of the hub and subsequent loss of control of the helicopter.

DATES: Effective December 1, 2010

DATES: Effective December 1, 2010, to all persons except those persons to whom it was made immediately effective by Emergency AD 2010-18-52, issued on August 23, 2010, which contained the requirements of this amendment.

Comments for inclusion in the Rules Docket must be received on or before January 18, 2011.

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

Federal eRulemaking Portal: Go to http:// www.regulations.gov. Follow the instructions for submitting comments.
Fax: 202-493-2251.

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 AD from MD Helicopters, Inc., 4555 East McDowell Road, Mesa, Arizona 85215-9734, USA, telephone (480) 346-6300 or (800) 388-3378, fax (480) 346-6813, or at serviceengineering@mdhelicopters.com.

Examining the Docket: You may examine the docket that contains the AD, any comments, and other information on the Internet at http:// www.regulations.gov, or 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 (800) 647-5527) 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.

FOR FURTHER INFORMATION CONTACT: Roger Durbin, Aviation Safety Engineer, FAA, Los Angeles Aircraft Certification Office, Airframe Branch, 3960 Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5233, fax (562) 627-5210.

SUPPLEMENTARY INFORMATION: On August 18, 2010, we issued Emergency AD 2010-18-51. That Emergency AD was prompted by two reports of cracks detected in the hub in the area near the flex beam bolt hole locations during maintenance on two MDHI Model MD900 helicopters. That Emergency AD required, within 4 hours time-in-service, visually inspecting the hub for a crack, paying particular attention to the area of the 5 flex beam bolt hole locations. If you found a crack, the Emergency AD 2010-18-51 required, before further flight, replacing the unairworthy hub with an airworthy hub. If you found a cracked hub, the Emergency AD also required, within 10 days of finding the crack, reporting the finding to the Los Angeles Aircraft Certification Office.

After we issued Emergency AD 2010-18-51, we discovered that we used part number (P/N) 900R2102008-103, -105, and -107, in the "Applicability'' section of the AD, which is incorrect. The correct P/ N is 900R2101008-103, -105, and -107. Therefore, we superseded Emergency AD 2010-18-51 with Emergency AD 2010-18-52. Emergency AD 2010-18-52 contains the same requirements as Emergency AD 2010-18-51 but corrects the P/N for the hub.

We have reviewed two letters issued by MDHI, dated August 11 and August 16, 2010, recommending visual inspections, feedback from operators, and diligence in conducting "preflight inspections'' of the hub. MDHI has received reports of two cracked hubs. The hubs were returned to MDHI for evaluation, and MDHI is analyzing the cracked hubs.

This unsafe condition is likely to exist or develop on other helicopters of the same type design. Therefore, this AD requires, within 4 hours time in service, visually inspecting the hub for a crack, paying particular attention to the area of the 5 flex beam bolt hole locations. If you find a crack, this AD requires, before further flight, replacing the unairworthy hub with an airworthy hub. If you find a cracked hub, this AD also requires, within 10 days of finding the crack, reporting the finding to the Los Angeles Aircraft Certification Office. This AD is an interim action pending the results of an ongoing investigation to determine further corrective actions.

The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the structural integrity and controllability of the helicopter. Therefore, a visual inspection of the hub is required within 4 hours time-in- service. If a crack is found, the unairworthy hub must be replaced with an airworthy hub before further flight, and this AD must be issued immediately.

Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual letters issued on August 23, 2010 to all known U.S. owners and operators of MDHI Model MD900 helicopters. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to 14 CFR 39.13 to make it effective to all persons. However, we have added a paragraph (c) to the AD to add information regarding the Paperwork Reduction Act Burden Statement. We have determined that this change neither increases the economic burden on any operator nor increases the scope of the AD.

We estimate that this AD will affect 33 helicopters of U.S. registry. The required inspection of the hub will take approximately 1 work hour per helicopter to accomplish at an average labor rate of $85 per work hour for a labor cost of $85 per helicopter. If a cracked hub is found, it will take approximately 11 hours per helicopter to replace the hub at an average labor rate of $85 per work hour for a labor cost of $935 per helicopter. Therefore, it is estimated that the actions required by this AD will require a total of 12 work hours per helicopter for a total labor cost of $1,020. Required parts will cost approximately $12,480 for each hub. Based on these figures, we estimate the total cost impact of the AD on U.S. operators to be $29,635. This estimation assumes that each affected helicopter is inspected and that only two helicopters have a hub that is cracked and needs to be replaced.

Comments Invited

This AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any written data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "Docket No. FAA-2010-1126; Directorate Identifier 2010-SW-078-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD. We will consider all comments received by the closing date and may amend the 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 AD. 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 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).

Regulatory Findings

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD 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.

For the reasons discussed above, I certify that the 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 an economic evaluation of the estimated costs to comply with this AD. See the AD docket to examine the 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.

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.

Sec. 39.13 [Amended]

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