Federal Aviation Administration (FAA), DOT.
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Notice of proposed rulemaking (NPRM).
We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 747SP series airplanes, and certain The Boeing Company Model 747-100B SUD and 747-300 series airplanes. This proposed AD was prompted by an evaluation by the design approval holder (DAH) indicating that the fuselage skin just above certain lap splice locations is subject to widespread fatigue damage (WFD). This proposed AD would require repetitive inspections for cracking of the fuselage skin above certain lap splice locations, and repair if necessary. We are proposing this AD to detect and correct fatigue cracking of the fuselage skin, which could result in reduced structural integrity of the airplane and sudden loss of cabin pressure.
We must receive comments on this proposed AD by April 22, 2013.
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.
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, P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. You may review copies of the service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. 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: 800-647-5527) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.
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FOR FURTHER INFORMATION CONTACT:
Nathan Weigand, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-6428; fax: 425-917-6590; email: Nathan.P.Weigand@faa.gov.
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Start Supplemental Information
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-2013-0205; Directorate Identifier 2012-NM-226-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.
Structural fatigue damage is progressive. It begins as minute cracks, and those cracks grow under the action of repeated stresses. This can happen because of normal operational conditions and design attributes, or because of isolated situations or incidents such as material defects, poor fabrication quality, or corrosion pits, dings, or scratches. Fatigue damage can occur locally, in small areas or structural design details, or globally. Global fatigue damage is general degradation of large areas of structure with similar structural details and stress levels. Multiple-site damage is global damage that occurs in a large structural element such as a single rivet line of a lap splice joining two large skin panels. Global damage can also occur in multiple elements such as adjacent frames or stringers. Multiple-site-damage and multiple-element-damage cracks are typically too small initially to be reliably detected with normal inspection methods. Without intervention, these cracks will grow, and eventually compromise the structural integrity of the airplane, in a condition known as widespread fatigue damage (WFD). As an airplane ages, WFD will likely occur, and will certainly occur if the airplane is operated long enough without any intervention.
The FAA's WFD final rule (75 FR 69746, November 15, 2010) became effective on January 14, 2011. The WFD rule requires certain actions to prevent catastrophic failure due to WFD throughout the operational life of certain existing transport category airplanes and all of these airplanes that will be certificated in the future. For existing and future airplanes subject to the WFD rule, the rule requires that DAHs establish a limit of validity (LOV) of the engineering data that support the structural maintenance program. Operators affected by the WFD rule may not fly an airplane beyond its LOV, unless an extended LOV is approved.
The WFD rule (75 FR 69746, November 15, 2010) does not require identifying and developing maintenance actions if the DAHs can show that such actions are not necessary to prevent WFD before the airplane reaches the LOV. Many LOVs, however, do depend on accomplishment of future maintenance actions. As stated in the WFD rule, any maintenance actions necessary to reach the LOV will be mandated by airworthiness directives through separate rulemaking actions.
We recognize that the WFD rule (75 FR 69746, November 15, 2010) is unusual in that it might depend on future rulemaking to fully achieve its safety objectives. In the context of WFD, this approach is necessary to enable DAHs to propose LOVs that allow operators the longest operational lives for their airplanes, and still ensure that WFD will not occur. This approach allows for an implementation strategy that provides flexibility to DAHs in determining the timing of service information development (with FAA approval), while providing operators with certainty regarding the LOV applicable to their airplanes.
Two operators of Model 757 airplanes have reported cracking on two airplanes that initiated at multiple locations on the inboard surface of the skin, along the edge of the chem-milled step just above the skin lap splice (which was addressed by AD 2011-01-15, Amendment 39-16572 (76 FR 1351, January 10, 2011)). No cracking of this kind has been reported on Model 747 airplanes, but analysis has determined that the Model 747 fuselage skin in certain areas might be susceptible to similar cracking. Such fatigue cracking of the fuselage skin could result in Start Printed Page 14721reduced structural integrity of the airplane and sudden loss of cabin pressure. The skin at the edge of chem-milled steps above certain skin lap splices has been determined to be structure that is susceptible to WFD.
Relevant Service Information
We reviewed Boeing Alert Service Bulletin 747-53A2854, dated September 17, 2012. For information on the procedures and compliance times, see this service information at http://www.regulations.gov by searching for Docket No. FAA-2013-0205.
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.”
The phrase “related investigative actions” might be used in this proposed AD. “Related investigative actions” are follow-on actions that: (1) are related to the primary actions, and (2) are actions that further investigate the nature of any condition found. Related investigative actions in an AD could include, for example, inspections.
In addition, the phrase “corrective actions” might be used in this proposed AD. “Corrective actions” are actions that correct or address any condition found. Corrective actions in an AD could include, for example, repairs.
Differences Between the Proposed AD and the Service Information
Boeing Alert Service Bulletin 747-53A2854, dated September 17, 2012, specifies to contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require repairing those conditions in one of the following ways:
- In accordance with a method that we approve; or
- Using data that meet the certification basis of the airplane, and that have been approved by the Boeing Commercial Airplanes Organization Designation Authorization (ODA) whom we have authorized to make those findings.
Costs of Compliance
We estimate that this proposed AD affects 4 airplanes of U.S. registry.
We estimate the following costs to comply with this proposed AD:
|Action||Labor cost||Parts cost||Cost per product||Cost on U.S. operators|
|Inspection||Up to 57 work-hours × $85 per hour = $4,845, per inspection cycle||$0||Up to $4,845, per inspection cycle||Up to $19,380, per inspection cycle.|
We have received no definitive data that would enable us 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.
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.
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.
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- Air transportation
- Aviation safety
- Incorporation by reference
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
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1. The authority citation for part 39 continues to read as follows: End Amendment Part
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2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD): End Amendment Part
The Boeing Company: Docket No. FAA-2013-0205; Directorate Identifier 2012-NM-226-AD.
(a) Comments Due Date
We must receive comments by April 22, 2013.
(b) Affected ADs
This AD applies to The Boeing Company airplanes, certificated in any category, identified in paragraphs (c)(1), (c)(2), and (c)(3) of this AD.
(1) All Model 747SP airplanes.
(2) Model 747-100B SUD airplanes, line numbers 636 and 655.
(3) Model 747-300 airplanes, line numbers 692 through 695 inclusive.
Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 53, Fuselage.Start Printed Page 14722
(e) Unsafe Condition
This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the fuselage skin just above certain lap splice locations is subject to widespread fatigue damage (WFD). We are issuing this AD to detect and correct fatigue cracking of the fuselage skin, which could result in reduced structural integrity of the airplane and sudden loss of cabin pressure.
Comply with this AD within the compliance times specified, unless already done.
(g) Repetitive Inspection
Perform external sliding probe eddy current inspections of the fuselage skin for cracking, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 747-53A2854, dated September 17, 2012, except where this service bulletin specifies to contact Boeing for inspection instructions, this AD requires doing the inspection using a method approved in accordance with the procedures specified in paragraph (h) of this AD. Do the inspection at the applicable initial compliance time specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2854, dated September 17, 2012, except where this service bulletin specifies a compliance time after the “original issue date of this service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.
(1) If no cracking is found during any inspection required by paragraph (g) of this AD, repeat the inspection thereafter at the applicable compliance time intervals specified in paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 747-53A2854, dated September 17, 2012.
(2) If any cracking is found during any inspection required by paragraph (g) of this AD: Before further flight, repair the cracking using a method approved in accordance with the procedures specified in paragraph (h) of this AD.
(h) Alternative Methods of Compliance (AMOCs)
(1) The Manager, Seattle 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. Information may be emailed to: 9-ANM-Seattle-ACO-AMOC-Requests@faa.gov.
(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 required by this AD if it is approved by the Boeing Commercial Airplanes Organization Designation Authorization (ODA) that has been authorized by the Manager, Seattle 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.
(i) Related Information
(1) For more information about this AD, contact Nathan Weigand, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-6428; fax: 425-917-6590; email: Nathan.P.Weigand@faa.gov.
(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone 206-544-5000, extension 1; fax 206-766-5680; Internet https://www.myboeingfleet.com. You may review copies of the service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425-227-1221.
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Issued in Renton, Washington, on February 20, 2013.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2013-05191 Filed 3-6-13; 8:45 am]
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