2010-32207. Airworthiness Directives; McDonnell Douglas Corporation Model MD-90-30 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for all Model MD-90-30 airplanes. This proposed AD would require repetitive inspections for cracking of the left and right upper center skin panels of the horizontal stabilizer, and corrective action if necessary. This proposed AD was prompted by a report of a crack found in the upper skin panel at the aft inboard corner of a right horizontal stabilizer. We are proposing this AD to detect and correct cracks in the horizontal stabilizer upper center skin panel. Uncorrected cracks might ultimately lead to the loss of overall structural integrity of the horizontal stabilizer.

DATES:

We must receive comments on this proposed AD by February 7, 2011.

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: [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: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, 3855 Lakewood Boulevard, MC D800-0019, Long Beach, California 90846-0001; telephone [phone], extension 2; fax [phone]; e-mail [e-mail]; 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 proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (phone: [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Roger Durbin, Aerospace Engineer, Los Angeles ACO, Airframe Branch, ANM-120L, FAA Los Angeles Aircraft Certification Office, 3960 Paramount Blvd, Lakewood, CA 90712-4137; telephone: [phone]; fax: [phone]; e-mail: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2010-1202; Directorate Identifier 2010-NM-167-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed 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 proposed AD.

Discussion

We have received a report of a crack to a Model MD-80 airplane upper center skin panel of the right horizontal stabilizer at the aft inboard corner during an inspection for cracks in the upper and lower aft skin panels of the horizontal stabilizer in accordance with AD 2007-10-04, Amendment 39-15045 (72 FR 25960, May 8, 2007). That airplane had accumulated 47,146 total flight hours and 26,490 total flight cycles when the crack was found. The cause of the cracking is suspected to be fatigue. The Model MD-90-30 airplane horizontal stabilizer is similar in design and loading to that of the Model MD-80 airplane horizontal stabilizer. Therefore, Model MD-90-30 airplanes may also be subject to the identified unsafe condition.

A crack in the upper center skin panel may transfer the load to the upper aft skin panel. This may result in the upper aft skin panel cracking faster than the existing inspection intervals that are required by AD 2009-13-08, Amendment 39-15947 (74 FR 30922, June 29, 2009). Uncorrected cracking could result in loss of the overall structural integrity of the horizontal stabilizer.

Relevant Service Information

We reviewed Boeing Alert Service Bulletin MD90-55A015, dated July 16, 2010. This service bulletin describes procedures for repetitive eddy current inspections, either (Option 1) two high frequency eddy current (ETHF) scans and one low frequency eddy current (ETLF) scan, or (Option 2) three ETHF scans, to detect cracking of the right and left upper center skin panels of the horizontal stabilizer. Corrective actions include replacing any cracked horizontal stabilizer upper center skin panel with a serviceable panel or contacting Boeing for possible temporary repair instructions.

The repetitive interval is 5,200 flight cycles or 2,500 flight cycles depending on the eddy current inspection option selected.

FAA's Determination

We are proposing 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 same type design.

Proposed AD Requirements

This proposed AD would require accomplishing the actions specified in the service information described previously, except as discussed under “Differences Between the Proposed AD and the Service Information.”

Differences Between the Proposed AD and the Service Information

Boeing Alert Service Bulletin MD90-55A015, dated July 16, 2010, provides an option to contact the manufacturer for instructions on how to repair cracking, but this proposed AD would require replacing the cracked skin panel.

Costs of Compliance

We estimate that this proposed AD will affect 19 airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:

Estimated Costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Inspection	4 work-hours × $85 per hour = $340 per inspection cycle	$0	$340 per inspection cycle	$6,460 per inspection cycle

We estimate the following costs to do any necessary repairs that would be required based on the results of the proposed inspection. We have no way of determining the number of aircraft that might need these repairs.

On-Condition Costs

Action	Labor cost	Parts cost	Cost per product
Skin panel replacement	648 work-hours × $85 per hour = $55,080	$55,608	$110,688

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

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

(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

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

McDonnell Douglas Corporation: Docket No. FAA-2010-1202; Directorate Identifier 2010-NM-167-AD.

Comments Due Date

(a) We must receive comments by February 7, 2011.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all McDonnell Douglas Corporation Model MD-90-30 airplanes, certificated in any category.

Subject

(d) Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 55: Stabilizers.

Unsafe Condition

(e) This AD was prompted by a report of a crack found in the upper center skin panel at the aft inboard corner of a right horizontal stabilizer. We are issuing this AD to detect and correct cracks in the upper center skin panel of the horizontal stabilizer. Uncorrected cracks might ultimately lead to the loss of overall structural integrity of the horizontal stabilizer.

Compliance

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

Inspections

(g) Before the accumulation of 20,000 total flight cycles, or within 3,778 flight cycles after the effective date of this AD, whichever occurs later, do eddy current inspections to detect cracking of the left and right upper center skin panels of the horizontal stabilizer, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A015, dated July 16, 2010.

(1) If no crack is found during any inspection required by paragraph (g) of this AD, repeat the applicable inspections thereafter at the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin MD90-55A015, dated July 16, 2010.

(2) If any crack is found during any inspection required by paragraph (g) of this AD, before further flight, replace the skin panel with a serviceable skin panel, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-55A015, dated July 16, 2010. Within 20,000 flight cycles after the replacement, do eddy current inspections as required by paragraph (g) of this AD.

Alternative Methods of Compliance (AMOCs)

(h)(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. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD.

(2) Before using any approved AMOC, notify your Principal Maintenance Inspector or Principal Avionics Inspector, as appropriate, or lacking a principal inspector, your local Flight Standards District Office.

(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

(i) For more information about this AD, contact Roger Durbin, Aerospace Engineer, Los Angeles ACO, Airframe Branch, ANM-120L, FAA Los Angeles Aircraft Certification Office, 3960 Paramount Blvd, Lakewood, CA 90712-4137; telephone: [phone]; fax: [phone]; e-mail: [e-mail].

(j) 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 [phone], extension 2; fax [phone]; e-mail [e-mail]; Internet https://www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, the FAA, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221.

Issued in Renton, Washington, on December 16, 2010.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.