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###### Department of Transportation

###### Federal Aviation Administration

          - 14 CFR Part 39
          - [Docket No. FAA-2010-0953; Directorate Identifier 2010-NM-010-AD; Amendment 39-16565; AD 2011-01-11]
          - RIN 2120-AA64

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Final rule.

# SUMMARY:

We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires repetitive high frequency eddy current inspections for cracking on the hinge bearing lugs of the left and right sides of the center section ribs of the horizontal stabilizer, and related investigative and corrective actions if necessary. This AD was prompted by reports of cracks found on either the left or right (or in one case, both) sides of the center section ribs of the horizontal stabilizer. We are issuing this AD to detect and correct cracking in the hinge bearing lugs of the center section of the left and right ribs, which could result in failure of the hinge bearing lugs and consequent inability of the horizontal stabilizer to sustain the required loads.

# DATES:

This AD is effective February 9, 2011.

The Director of the Federal Register approved the incorporation by reference of a certain publication listed in the AD as of February 9, 2011.

# ADDRESSES:

                        For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, 3855 Lakewood Boulevard, MC D800-0019, Long Beach, California 90846-0001; telephone 206-544-5000, extension 2; fax 206-766-5683; e-mail                         *dse.boecom@boeing.com;*                         Internet                         *https://www.myboeingfleet.com.*                         You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221.                    

## 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 address for the Docket Office (phone: 800-647-5527) is Document Management Facility, U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.                

# FOR FURTHER INFORMATION CONTACT:

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

#                     SUPPLEMENTARY INFORMATION:                          ( print page 431)    

## Discussion

                    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to the specified products. That NPRM published in the                     **Federal Register**                     on October 1, 2010 (75 FR 60665). That NPRM proposed to require repetitive high frequency eddy current inspections for cracking on the hinge bearing lugs of the left and right sides of the center section ribs of the horizontal stabilizer, and related investigative and corrective actions if necessary.                

## Comments

We gave the public the opportunity to participate in developing this AD. We received no comments on the NPRM or on the determination of the cost to the public.

## Explanation of Change to Applicability

We have revised the existing AD to identify model designations as published in the most recent type certificate data sheet for the affected models.

## Conclusion

We reviewed the relevant data and determined that air safety and the public interest require adopting the AD as proposed—except for minor editorial changes and the change described previously. We have determined that these minor changes:
    - Are consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and
    - Do not add any additional burden upon the public than was already proposed in the NPRM.

## Conclusion

We reviewed the relevant data and determined that air safety and the public interest require adopting the AD as proposed.

## Interim Action

We consider this AD interim action. The manufacturer is currently developing a modification that will address the unsafe condition identified in this AD. Once this modification is developed, approved, and available, we might consider additional rulemaking.

## Costs of Compliance

We estimate that this AD affects 16 airplanes of U.S. registry. We also estimate that it takes about 2 work-hours per product to comply with this AD. The average labor rate is $85 per work-hour. Based on these figures, we estimate the cost of this AD to the U.S. operators to be $2,720, or $170 per product.

## 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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

# 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 airworthiness directive (AD): 

**2011-01-11 The Boeing Company:**                             Amendment 39-16565; Docket No. FAA-2010-0953; Directorate Identifier 2010-NM-010-AD.                        

## Effective Date

(a) This AD is effective February 9, 2011.

## Affected ADs

(b) None.

## Applicability

(c) This AD applies to all The Boeing Company Model MD-90-30 airplanes, certificated in any category.

## Subject

(d) Air Transport Association (ATA) of America Code 55: Stabilizers.

## Unsafe Condition

(e) This AD results from reports of cracks found on either the left or right (or in one case, both) sides of the center section ribs of the horizontal stabilizer. The Federal Aviation Administration is issuing this AD to detect and correct cracking in the hinge bearing lugs of the center section of the left and right ribs, which could result in failure of the hinge bearing lugs and consequent inability of the horizontal stabilizer to sustain the required loads.

## Compliance

(f) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

## Repetitive Inspections and Corrective Actions for Cracking

(g) At the applicable time in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010, except as required by paragraph (n) of this AD, do a high frequency eddy current (HFEC) inspection for cracking on the hinge bearing lugs of the left and right sides of the center section ribs of the horizontal stabilizer, and do all applicable related investigative actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010. Do all applicable related investigative actions before further flight.

(h) If during any inspection required by paragraph (g) of this AD, no cracking is found, repeat the inspection required by paragraph (g) of this AD thereafter at intervals not to exceed 1,680 flight cycles.

                            (i) If during any inspection required by paragraph (g) or (h) of this AD, any crack is found having a length between Points `A' and `B' less than or equal to 0.15 inch and crack length between Points `C' and `D' less than or equal to 0.05 inch, as identified in Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010: Before further flight, blend out the crack; and within                                   ( print page 432)                                1,000 flight cycles after doing the blend out, do an HFEC inspection of the blend out on the center section rib hinge bearing lug; in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010. Repeat the HFEC inspection of the blend out thereafter at intervals not to exceed 400 flight cycles until the replacement specified by paragraph (j) is done.                        

(j) If any cracking is detected during any inspection required by paragraph (i) of this AD, before further flight, replace the horizontal stabilizer center section rib with a new horizontal stabilizer center section rib, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010.

(k) If during any inspection required by paragraph (g) or (h) of this AD, any crack is found having a length between Points `A' and `B' greater than 0.15 inch or crack length between Points `C' and `D' greater than 0.05 inch, as identified in Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010: Before further flight, replace the horizontal stabilizer center section rib with a new horizontal stabilizer center section rib, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010.

(l) For any airplane having a horizontal stabilizer center section rib replaced during the actions required by paragraph (j) or (k) of this AD: Before the accumulation of 7,200 total flight cycles on the new horizontal stabilizer center section rib, do the actions required by paragraph (g) of this AD, and do all applicable actions specified in paragraphs (h), (i), (j), and (k) of this AD.

## Credit for Actions Accomplished According to Previous Issue of Service Bulletin

(m) Actions accomplished before the effective date of this AD according to Boeing Alert Service Bulletin MD90-55A016, dated December 16, 2009, are considered acceptable for compliance with the corresponding actions required by paragraphs (g), (h), (i), (j), and (k) of this AD.

## Exception to the Service Bulletin

(n) Where Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010, specifies a compliance time “after the original issue date on the service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.

## Alternative Methods of Compliance (AMOCs)

(o)(1) The Manager, Los Angeles Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. Send information to 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.

(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 principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

(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 the Boeing Commercial Airplanes Organization Designation Authorization (ODA) that 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.

## Related Information

(p) For more information about this AD, contact 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.

## Material Incorporated by Reference

(q) You must use Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010, 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 Boeing Alert Service Bulletin MD90-55A016, Revision 1, dated February 17, 2010, under 5 U.S.C. 552(a) and 1 CFR part 51.

                            (2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, 3855 Lakewood Boulevard, MC D800-0019, Long Beach, California 90846-0001; telephone 206-544-5000, extension 2; fax 206-766-5683; e-mail                             *dse.boecom@boeing.com;*                             Internet                             *https://www.myboeingfleet.com.*

(3) You may review copies of the service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221.

                            (4) You may also review copies of the service information that is incorporated by reference at the National Archives and Records Administration (NARA). For information on the availability of this material at an NARA facility, 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 December 22, 2010.

Jeffrey E. Duven,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 2010-32993 Filed 1-4-11; 8:45 am]

BILLING CODE 4910-13-P