2019-13057. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for all The Boeing Company Model MD-90-30 airplanes. This proposed AD was prompted by reports indicating that certain center wing stringers and skins have been identified to potentially be susceptible to cracking. This proposed AD would require repetitive eddy current, low frequency (ETLF) inspections of the left and right side fastener holes for any crack; repetitive eddy current, high frequency (ETHF) inspections of the lower skin for any crack; and repair if any crack is found. The FAA is proposing this AD to address the unsafe condition on these products.

DATES:

The FAA must receive comments on this proposed AD by August 5, 2019.

ADDRESSES:

You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, 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 NPRM, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740 5600; telephone [phone]; internet https://www.myboeingfleet.com. You may view this service information at the FAA, Transport Standards Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195. It is also available on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2019-0406.

Examining the AD Docket

You may examine the AD docket on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2019-0406; or in person at Docket Operations between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this NPRM, the regulatory evaluation, any comments received, and other information. The street address for Docket Operations is listed above. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

David Truong, Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: [phone]; fax: [phone]; email: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites 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-2019-0406; Product Identifier 2019-NM-059-AD” at the beginning of your comments. The FAA specifically invites comments on the overall regulatory, economic, environmental, and energy aspects of this NPRM. The FAA will consider all comments received by the closing date and may amend this NPRM because of those comments.

The FAA will post all comments, without change, to http://www.regulations.gov,, including any personal information you provide. The FAA will also post a report summarizing each substantive verbal contact the agency receives about this NPRM.

Discussion

The FAA has received reports indicating that the fastener holes common to stringers (S) S-11 through S-22, and around the external bracket angle at S-18 and S-19 have been identified to potentially be susceptible to cracking on the Model MD-90 airplanes. This determination is based on Model MD-80 airplane service experience. The Model MD-80 and Model MD-90 wings share the same basic design and have similar stresses.

Operators of Model MD-80 airplanes have reported finding cracks in the center wing lower stringers, lower stringer end fittings, and lower forward and aft skins. The cracks in stringers occur at the inboard end where they are joined to the airplane centerline by end fittings. Cracks in the end fittings occur at the outboard end where they attach to stringers. The wing skin cracks occur underneath a cracked stringer. The cause of the cracks has been determined to be from fatigue. The Boeing Company has not received any reports of cracks on Model MD-90 airplanes; however, the similarities with the Model MD-80 wings require agency action. If not addressed, cracking of the center wing stringers and skins could result in the inability of the structure to sustain limit loads, and adversely affect the structural integrity of the airplane.

Other Relevant Rulemaking

The FAA issued AD 2016-07-28 (81 FR 21253, April 11, 2016) for all The Boeing Company Model DC-9-81 (MD- 81), DC-9-82 (MD-82), DC-9-83 (MD-83), and DC-9-87 (MD-87) airplanes, and Model MD-88 airplanes. That AD requires repetitive ETHF inspections for any cracking in the left and right side center wing lower skin, and corrective actions if necessary. That AD addresses cracks at S-15, S-16, or S-17, associated end fittings, and skins in the center wing fuel tank where the stringers meet the end fittings near Xcw=13 and Xcw=15. Such cracking could cause structural failure of the wings. Since that AD was issued, cracking has been found at fastener holes common to stringers S-11 through S-22, and around the external bracket angle at S-18 and S-19. These areas were not addressed in AD 2016-07-28 or Boeing Alert Service Bulletin MD80-57A244, dated March 3, 2016, which is the service information operators are required to follow to complete the actions required by AD 2016-07-28. Boeing is developing new service information for Model MD-80 airplanes to address these additional areas where cracking was found. The FAA will consider further rulemaking to address the identified unsafe condition for Model MD-80 airplanes once this service information is approved.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Boeing Alert Service Bulletin MD90-57A031, dated March 19, 2019. This service information describes procedures for repetitive ETLF inspections of the left and right side fastener holes for any crack, repetitive ETHF inspections of the lower skin for any crack, and repair if any crack is found.

This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.

FAA's Determination

The FAA is 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. For information on the procedures and compliance times, see this service information at http://www.regulations.gov by searching for and locating Docket No. FAA-2019-0406.

Costs of Compliance

The FAA estimates that this proposed AD affects 43 airplanes of U.S. registry. The FAA estimates 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	30 work-hours × $85 per hour = $2,550 per inspection cycle	$0	$2,550 per inspection cycle	$109,650 per inspection cycle.

The FAA has received no definitive data that would enable the agency to provide cost estimates for the on-condition actions specified in this proposed 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.

The FAA is 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.

This proposed AD is issued in accordance with authority delegated by the Executive Director, Aircraft Certification Service, as authorized by FAA Order 8000.51C. In accordance with that order, issuance of ADs is normally a function of the Compliance and Airworthiness Division, but during this transition period, the Executive Director has delegated the authority to issue ADs applicable to transport category airplanes and associated appliances to the Director of the System Oversight Division.

Regulatory Findings

The FAA 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) Will not affect intrastate aviation in Alaska, 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.

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):

The Boeing Company: Docket No. FAA-2019-0406; Product Identifier 2019-NM-059-AD.

(a) Comments Due Date

The FAA must receive comments by August 5, 2019.

(b) Affected ADs

None.

(c) Applicability

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

(d) Subject

Air Transport Association (ATA) of America Code 57, Wings.

(e) Unsafe Condition

This AD was prompted by reports indicating that certain center wing stringers and skins have been identified to potentially be susceptible to cracking. The FAA is issuing this AD to address cracking of the center wing stringers and skins, which could result in the inability of the structure to sustain limit loads, and adversely affect the structural integrity of the airplane.

(f) Compliance

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

(g) Required Actions

Except as specified in paragraph (h) of this AD: At the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin MD90-57A031, dated March 19, 2019, do all applicable actions identified as “RC” (required for compliance) in, and in accordance with, the Accomplishment Instructions of Boeing Alert Service Bulletin MD90-57A031, dated March 19, 2019.

(h) Exceptions to Service Information Specifications

(1) For purposes of determining compliance with the requirements of this AD: Where Boeing Alert Service Bulletin MD90-57A031, dated March 19, 2019, uses the phrase “the original issue date of this service bulletin,” this AD requires using “the effective date of this AD.”

(2) Where Boeing Alert Service Bulletin MD90-57A031, dated March 19, 2019, specifies contacting Boeing for repair instructions and doing the repair: This AD requires doing the repair using a method approved in accordance with the procedures specified in paragraph (i) of this AD.

(i) Alternative Methods of Compliance (AMOCs)

(1) The Manager, Los Angeles ACO Branch, 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 certification office, send it to the attention of the person identified in paragraph (j)(1) of this AD. Information may be emailed to [e-mail].

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.

(3) An AMOC that provides an acceptable level of safety may be used for any repair, modification, or alteration required by this AD if it is approved by The Boeing Company Organization Designation Authorization (ODA) that has been authorized by the Manager, Los Angeles ACO Branch, FAA, to make those findings. To be approved, the repair method, modification deviation, or alteration deviation must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

(4) Except as specified by paragraph (h) of this AD: For service information that contains steps that are labeled as Required for Compliance (RC), the provisions of paragraphs (i)(4)(i) and (i)(4)(ii) of this AD apply.

(i) The steps labeled as RC, including substeps under an RC step and any figures identified in an RC step, must be done to comply with the AD. If a step or substep is labeled “RC Exempt,” then the RC requirement is removed from that step or substep. An AMOC is required for any deviations to RC steps, including substeps and identified figures.

(ii) Steps not labeled as RC may be deviated from using accepted methods in accordance with the operator's maintenance or inspection program without obtaining approval of an AMOC, provided the RC steps, including substeps and identified figures, can still be done as specified, and the airplane can be put back in an airworthy condition.

(j) Related Information

(1) For more information about this AD, contact David Truong, Aerospace Engineer, Airframe Section, FAA, Los Angeles ACO Branch, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: [phone]; fax: [phone]; email: [e-mail].

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Contractual & Data Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 90740 5600; telephone [phone]; internet https://www.myboeingfleet.com. You may view this service information at the FAA, Transport Standards Branch, 2200 South 216th St., Des Moines, WA. For information on the availability of this material at the FAA, call 206-231-3195.

Issued in Des Moines, Washington, on June 4, 2019.

Michael Kaszycki,

Acting Director, System Oversight Division, Aircraft Certification Service.