2014-08730. Airworthiness Directives; the Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain the Boeing Company Model DC-9-10, DC-9-20, DC-9-30, DC-9-40, and DC-9-50 series airplanes. This proposed AD was prompted by an evaluation by the design approval holder (DAH) indicating that the bulkhead dome tees, which connect the bulkhead web to the fuselage, are subject to widespread fatigue damage (WFD). This proposed AD would require repetitive inspections of the improved ventral aft pressure bulkhead tees and replacement if necessary. We are proposing this AD to detect and correct fatigue cracking of the bulkhead dome tees, which could result in reduced structural integrity and rapid decompression of the airplane.

DATES:

We must receive comments on this proposed AD by June 2, 2014.

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 proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, 3855 Lakewood Boulevard, MC D800-0019, Long Beach, CA 90846-0001; telephone [phone], extension 2; fax [phone]; Internet https://www.myboeingfleet.com. You may view this referenced 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 by searching for and locating Docket No. FAA-2014-0232; 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:

Eric Schrieber, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, CA 90712-4137; phone: [phone]; fax: [phone]; email: [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-2014-0232; Directorate Identifier 2013-NM-100-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

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 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 structural 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.

In the context of WFD, this action 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.

This AD was prompted by an evaluation by the DAH indicating that the improved (shot-peened) ventral aft pressure bulkhead dome tees, which connect the bulkhead web to the fuselage, are subject to WFD. No new improved (shot-peened) tees have been found cracked to date, but it has been determined that these improved tees could crack before the airplane's limit of validity is reached. This condition, if not corrected, could result in reduced structural integrity and rapid decompression of the airplane.

Relevant Service Information

We reviewed McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995. For information on the procedures and compliance times, see this service information at http://www.regulations.gov by searching for Docket No. FAA-2014-0232.

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 these same type designs.

Proposed AD Requirements

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

Differences Between This Proposed AD and the Service Information

McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995, did not specify compliance times for inspections of the new improved (shot-peened) tees. We have determined that the compliance time specified in this proposed AD adequately addresses the unsafe condition. This difference has been coordinated with The Boeing Company.

Although McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995, describes inspection procedures for the original design tees, the inspection procedures also apply to the improved (shot-peened) tees specified in this AD.

Although McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995, notes that replacing all six aft pressure bulkhead tee sections with new improved tee sections terminates the repetitive inspection requirements, this proposed AD does not allow that terminating action because the new improved tee could crack before the airplane's limit of validity is reached.

Although Table 1 of Figure 4, and paragraph 3, “Material Information,” of McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995, specify tee part numbers of SR09530056-3, SR09530056-5, SR09530056-6, SR09530056-7, SR09530056-8, SR09530056-9, 5910163-387, 5910163-389, 5910163-391, 5910163-392, 5910163-393, or 5910163-394, the complete lists of part numbers are listed in paragraphs (h) and (k) of this proposed AD.

These differences have been coordinated with The Boeing Company.

Related Rulemaking

AD 96-16-04, Amendment 39-9704 (61 FR 39860, July 31, 1996) requires repetitive inspections of the original tee in accordance with McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995, whether or not the original tee was replaced. AD 96-16-04 did not address WFD and, therefore, allowed replacement of the tee with a new improved tee as a terminating action for repetitive inspections.

Explanation of Compliance Time

The compliance time for the replacement specified in this proposed AD for addressing WFD was established to ensure that discrepant structure is replaced before WFD develops in airplanes. Standard inspection techniques cannot be relied on to detect WFD before it becomes a hazard to flight. We will not grant any extensions of the compliance time to complete any AD-mandated service bulletin related to WFD without extensive new data that would substantiate and clearly warrant such an extension.

Costs of Compliance

We estimate that this proposed AD affects 48 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	Up to 148 work-hours × $85 per hour = $12,580 per inspection cycle	$0	Up to $12,580 per inspection cycle	Up to $603,840 per inspection cycle.

We estimate the following costs to do any necessary replacements 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 replacements:

On-Condition Costs

Action	Labor cost	Parts cost	Cost per product
Replacement	4,000 work-hours × $85 per hour = $340,000	$26,000	$366,000

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):

The Boeing Company: Docket No. FAA-2014-0232; Directorate Identifier 2013-NM-100-AD.

(a) Comments Due Date

We must receive comments by June 2, 2014.

(b) Affected ADs

This AD affects certain requirements of AD 96-16-04, Amendment 39-9704 (61 FR 39860, July 31, 1996).

(c) Applicability

This AD applies to The Boeing Company Model DC-9-11, DC-9-12, DC-9-13, DC-9-14, DC-9-15, and DC-9-15F airplanes; Model DC-9-21 airplanes; Model DC-9-31, DC-9-32, DC-9-32 (VC-9C), DC-9-32F, DC-9-33F, DC-9-34, DC-9-34F, and DC-9-32F (C-9A, C-9B) airplanes; Model DC-9-41 airplanes; and Model DC-9-51 airplanes; certificated in any category; equipped with a ventral aft pressure bulkhead.

(d) Subject

Air Transport Association (ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

This AD was prompted by an evaluation by the design approval holder (DAH) indicating that the improved (shot-peened) ventral aft pressure bulkhead dome tees, which connect the bulkhead web to the fuselage, are subject to widespread fatigue damage (WFD). We are issuing this AD to detect and correct fatigue cracking of the improved (shot-peened) ventral aft pressure bulkhead dome tees connecting the bulkhead web to the fuselage, which could result in reduced structural integrity and rapid decompression of the airplane.

(f) Compliance

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

(g) Definitions

(1) For the purposes of this AD, the term “original tee section” refers to the original (non-peened) ventral aft pressure bulkhead web to fuselage skin attach tee sections.

(2) For the purposes of this AD, the term “improved tee section” refers to improved (shot peened) ventral aft pressure bulkhead web to fuselage skin attach tee sections.

(h) Inspections

For airplanes on which an improved tee section having P/N 5910130-389, 5910130-391, 5910130-392, 5910130-393, 5910130-394, 5910130-387, SR09530001-19, SR09530001-21, SR09530001-22, SR09530001-23, SR09530001-24, SR09530001-25, SR09530001-35, SR09530001-29, SR09530001-30, SR09530001-31, SR09530001-32, SR09530001-33, SR09530056-3, SR09530056-5, SR09530056-6, SR09530056-7, SR09530056-8, SR09530056-9, SR09530056-19, SR09530056-21, SR09530056-22, SR09530056-23, SR09530056-24, or SR09530056-25, is installed: At the applicable time specified in paragraph (i)(1) or (i)(2) of this AD, do general visual and low frequency eddy current inspections (Option I), or high and low frequency eddy current inspections (Option II), for cracking of the improved tee sections, in accordance with the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995.

(i) Compliance Times

(1) For Option I and Option II inspections specified in paragraph (h) of this AD: If the time of installation of an improved tee section having a part number listed in paragraph (h) of this AD, is known, do the initial inspection required by paragraph (h) of this AD within 70,000 flight cycles after installation of the improved tee section, or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.

(2) For Option I and Option II inspections specified in paragraph (h) of this AD: If the time of installation of an improved tee section having a part number listed in paragraph (h) of this AD, is not known, do the initial inspection required by paragraph (h) of this AD before the accumulation of 105,000 total flight cycles on the airplane or within 1,500 flight cycles after the effective date of this AD, whichever occurs later.

(j) Repetitive Inspections

If no cracking is found during the inspection required by paragraph (h) of this AD: Do the actions specified in paragraph (j)(1) or (j)(2) of this AD, as applicable, in accordance with the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995.

(1) For Option I: If Option I was used for the inspection required by paragraph (h) of this AD, repeat the inspections specified in paragraphs (j)(1)(i), (j)(1)(ii), and (j)(1)(iii) of this AD at the intervals specified in paragraphs (j)(1)(i), (j)(1)(ii), and (j)(1)(iii) of this AD.

(i) Repeat the low frequency eddy current inspection for cracking of side areas above the floor between longerons L7 and L17 on the fuselage, at intervals not to exceed 1,500 flight cycles.

(ii) Repeat the general visual inspection for cracking of the top and lower areas from longeron L7 left side to longeron L7 right side, and lower fuselage longeron L17 to longeron L20 on the left and right sides, at intervals not to exceed 1,500 flight cycles.

(iii) Repeat the general visual inspection for cracking of the bottom areas from longeron L20 left side to longeron L20 right side, at intervals not to exceed 3,500 flight cycles.

(2) For Option II: If Option II was used for the inspection required by paragraph (h) of this AD, repeat the high and low frequency eddy current inspection for cracking around the entire periphery of the fuselage on the forward side of the bulkhead, at intervals not to exceed 2,500 flight cycles.

(k) Corrective Actions and Post-Replacement Inspections

If any cracking is found during any inspection required by paragraph (h) or (j) of this AD: Before further pressurized flight, replace each cracked tee section with an airworthy tee section having a part number listed in paragraph (h) of this AD, or with an original tee section having P/N 5910130-47, 5910130-51, 5910130-53, 5910130-54, 5910130-55, or 5910130-56, in accordance with the Accomplishment Instructions of McDonnell Douglas Alert Service Bulletin A53-232, Revision 2, dated April 28, 1995.

(1) If the tee section is replaced with an improved tee section listed in paragraph (h) of this AD, prior to the accumulation of 70,000 flight cycles after installation, inspect the tee section in accordance with paragraph (h) of this AD and do all applicable corrective actions and repetitive inspections in accordance with and at the times specified in paragraphs (j) and (k) of this AD.

(2) If the tee section is replaced with an original tee section listed in paragraph (k) of this AD, prior to the accumulation of 35,000 flight cycles after installation, inspect the tee section in accordance with paragraph (h) of this AD and do all applicable corrective actions and repetitive inspections in accordance with and at the times specified in paragraphs (j) and (k) of this AD.

(l) Alternative Methods of Compliance (AMOCs)

(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 paragraph (m)(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 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 14 CFR 25.571, Amendment 45, and the approval must specifically refer to this AD.

(m) Related Information

(1) For more information about this AD, contact Eric Schrieber, Aerospace Engineer, Airframe Branch, ANM-120L, FAA, Los Angeles Aircraft Certification Office, 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: Data & Services Management, 3855 Lakewood Boulevard, MC D800-0019, Long Beach, CA 90846-0001; telephone [phone], extension 2; fax [phone]; Internet https://www.myboeingfleet.com. You may view this referenced 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.

Issued in Renton, Washington, on April 7, 2014.

John P. Piccola,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.