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###### Department of Transportation

###### Federal Aviation Administration 

          - 14 CFR Part 39 
          - [Docket No. FAA-2008-0946; Directorate Identifier 2008-NM-147-AD; Amendment 39-15667; AD 2008-18-10] 
          - RIN 2120-AA64 

# AGENCY:

Federal Aviation Administration (FAA), DOT. 

# ACTION:

Final rule; request for comments. 

# SUMMARY:

We are adopting a new airworthiness directive (AD) for certain McDonnell Douglas Model MD-90-30 airplanes. This AD requires a detailed inspection for certain defects of the upper fasteners of the aft mount support fitting of the left and right engines and corrective actions if necessary. This AD results from reports of loose, cracked, or missing fasteners in the aft mount support fitting of the left and right engines. We are issuing this AD to detect and correct loose, cracked, or missing fasteners in the engine aft support mount fitting, which could lead to separation of the support fitting from the pylon, which could result in separation of the engine from the airplane. 

# DATES:

This AD is effective September 24, 2008. 

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in this AD as of September 24, 2008. 

We must receive comments on this AD by November 10, 2008. 

# ADDRESSES:

You may send comments by any of the following methods: 
      -  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.                     

For service information identified in this AD, contact Boeing Commercial Airplanes, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Data and Service Management, Dept. C1-L5A (D800-0024). 

## Examining the AD Docket 

                    You may examine the AD docket on the Internet at                     *http://www.regulations.gov*; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (telephone 800-647-5527) is in the                     **ADDRESSES**                     section. Comments will be available in the AD docket shortly after receipt.                 

# FOR FURTHER INFORMATION CONTACT:

Roger Durbin, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5233; fax (562) 627-5210. 

# SUPPLEMENTARY INFORMATION:

## Discussion 

                    We have received reports of loose, cracked, or missing fasteners in the aft mount support fitting of the left and right engines on several McDonnell Douglas Model MD-90-30 airplanes. The airplanes had accumulated between 18,767 and 25,400 total flight hours and between 15,841 and 27,000 total flight cycles. A safety assessment of the missing fasteners has concluded that loose or discrepant fasteners in the top                           ( print page 52204)                        horizontal row, common with the pylon skin, significantly decrease the margin of safety of the aft mount support installation at the design limit load. Loose, cracked, or missing fasteners in the engine aft mount support fitting could lead to separation of the support fitting from the pylon. This condition, if not corrected, could result in separation of the engine from the airplane.                 

## Relevant Service Information 

We reviewed Boeing Alert Service Bulletin MD90-54A002, dated August 1, 2008. The service bulletin describes procedures for doing a detailed inspection for certain defects of the upper fasteners of the aft mount support fitting of the left and right engines, and corrective action as applicable. The detailed inspection consists of the following actions: (1) A general visual inspection of the upper fasteners for any missing, loose, or damaged fasteners, (2) a gap check between the washers and structure or between the fastener heads and structure, if applicable, and (3) a torque check of the fastener nuts, if applicable. The corrective action includes replacing all fasteners if any defect is found. 

## FAA's Determination and Requirements of This AD 

We are issuing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the(se) same type design(s). This AD requires accomplishing the actions specified in the service information described previously. 

## Interim Action 

This is considered to be interim action until final action is identified, at which time we might consider further rulemaking. 

## FAA's Justification and Determination of the Effective Date 

Loose, cracked, or missing fasteners in the engine aft mount support fitting could lead to separation of the support fitting from the pylon, possibly resulting in separation of the engine from the airplane. Because of our requirement to promote safe flight of civil aircraft and thus, the critical need to assure structural integrity of the engine aft mount support fitting and the short compliance time involved with this action, this AD must be issued immediately. 

Because an unsafe condition exists that requires the immediate adoption of this AD, we find that notice and opportunity for prior public comment hereon are impracticable and that good cause exists for making this amendment effective in less than 30 days. 

## Comments Invited 

                    This AD is a final rule that involves requirements affecting flight safety, and we did not provide you with notice and an opportunity to provide your comments before it becomes effective. However, we invite you to send any written data, views, or arguments about this AD. Send your comments to an address listed under the                     **ADDRESSES**                     section. Include “Docket No. FAA-2008-0946; Directorate Identifier 2008-NM-147-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this AD. We will consider all comments received by the closing date and may amend this AD because 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 we receive about this AD.                 

## 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. 

## Regulatory Findings 

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 this AD:

(1) Is not a “significant regulatory action” under Executive Order 12866, (2) Is not a “significant rule” under 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. 

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket. 

# List of Subjects in 14 CFR Part 39

      - Air transportation
      - Aircraft
      - Aviation safety
      - Incorporation by reference
      - Safety

## Adoption of the Amendment 

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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 

2. The FAA amends § 39.13 by adding the following new AD: 

**2008-18-10 McDonnell Douglas:**                             Amendment 39-15667. Docket No. FAA-2008-0946; Directorate Identifier 2008-NM-147-AD.                         

## Effective Date 

(a) This airworthiness directive (AD) is effective September 24, 2008. 

## Affected ADs 

(b) None. 

## Applicability 

(c) This AD applies to McDonnell Douglas Model MD-90-30 airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin MD90-54A002, dated August 1, 2008. 

## Unsafe Condition 

(d) This AD results from reports of loose, cracked, or missing fasteners in the aft mount support fitting of the left and right engines. We are issuing this AD to detect and correct loose, cracked, or missing fasteners in the engine aft support mount fitting, which could lead to separation of the support fitting from the pylon, which could result in separation of the engine from the airplane. 

## Compliance 

(e) Comply with this AD within the compliance times specified, unless already done. 

## Detailed Inspection 

                            (f) Within 703 flight cycles after the effective date of this AD, do a detailed                                   ( print page 52205)                                inspection for any defect (missing, loose, or damaged fasteners; incorrect gap between washers and structure or between fastener heads and structure; or incorrect torque of fastener nuts) of the upper fasteners of the aft mount support fitting of the left and right engines, and do all the applicable corrective actions before further flight, by accomplishing all of the applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-54A002, dated August 1, 2008.                         

## Credit for Actions Done per Multiple Operator Message (MOM) 

(g) Actions done before the effective date of this AD in accordance with Boeing MOM 1-893882781-2, dated July 25, 2008, are acceptable for compliance with the requirements of paragraph (f) of this AD. 

## Alternative Methods of Compliance (AMOCs) 

(h)(1) The Manager, Los Angeles Certification Office (ACO), FAA, ATTN: Roger Durbin, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles ACO, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone (562) 627-5233; fax (562) 627-5210; has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. 

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO. 

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who has been authorized by the Manager, Los Angeles ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD. 

## Material Incorporated by Reference 

(i) You must use Boeing Alert Service Bulletin MD90-54A002, dated August 1, 2008, to do the actions required by this AD, unless the AD specifies otherwise. 

(1) The Director of the Federal Register approved the incorporation by reference of this service information under 5 U.S.C. 552(a) and 1 CFR part 51. 

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Data and Service Management, Dept. C1-L5A (D800-0024). 

                            (3) You may review copies of the service information incorporated by reference at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to:                             *http://www.archives.gov/​federal_​register/​code_​of_​federal_​regulations/​ibr_​locations.html*.                         

Issued in Renton, Washington, on August 25, 2008. 

Dionne Palermo, 

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. E8-20494 Filed 9-8-08; 8:45 am] 

BILLING CODE 4910-13-P