2013-05505. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to supersede an existing airworthiness directive (AD) that applies to all The Boeing Company Model 737-300, -400, and -500 series airplanes. The existing AD currently requires repetitive inspections of the downstop assemblies on the main tracks of the No. 2, 3, 4, and No. 5 slats and the inboard track of the No. 1 and 6 slats to verify if any parts are missing, damaged, or in the wrong order; other specified actions; and related investigative and corrective actions if necessary. Since we issued that AD, the manufacturer has developed a modification, which, when installed, would terminate the repetitive inspections. This proposed AD would add an inspection of the slat can interior for foreign object debris (FOD), and removal of any FOD found; modification of the slat track hardware; an inspection for FOD and for damage to the interior surface of the slat cans; and related investigative and corrective actions, if necessary. We are proposing this AD to prevent loose or missing parts in the main slat track downstop assemblies, which could puncture the slat track housing and result in a fuel leak and consequent fire.

DATES:

We must receive comments on this proposed AD by April 25, 2013.

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, P. O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; 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:

Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, Washington 98057-3356; 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 proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2013-0207; Directorate Identifier 2011-NM-071-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

On March 11, 2008, we issued AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008), for all The Boeing Company Model 737-300, -400, and -500 series airplanes. That AD requires repetitive inspections of the downstop assemblies on the main tracks of the No. 2, 3, 4, and 5 slats and the inboard track of the No. 1 and 6 slats to verify if any parts are missing, damaged, or in the wrong order; and related investigative and corrective actions if necessary. That AD resulted from reports of fuel leaking from a puncture in the slat track housing. We issued that AD to detect and correct loose or missing parts in the main slat track downstop assemblies, which could puncture the slat track housing and result in a fuel leak and consequent fire.

Actions Since Existing AD (73 FR 15397, March 24, 2008) Was Issued

The preamble to AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008), specifies that we consider the requirements “interim action” and that the manufacturer was developing a modification to address the unsafe condition. That AD explains that we might consider further rulemaking if a modification is developed, approved, and available. The manufacturer now has developed such a modification, and we have determined that further rulemaking is indeed necessary; this proposed AD follows from that determination.

Relevant Service Information

AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008), refers to Boeing Alert Service Bulletin 737-57A1301, dated February 5, 2008, as the appropriate source of service information for the required actions. Boeing has since revised this service information. We reviewed Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011, which adds procedures for inspecting the slat can interior for foreign object debris (FOD), removing any FOD found, modifying the slat track hardware; an inspection for FOD and a one-time inspection for damage to the interior surface of the slat cans for the inboard and outboard tracks of slats No. 2 through 5 and the inboard slats of tracks No. 1 and 6; and related investigative and corrective actions if necessary. Modifying the slat track hardware eliminates the need for the repetitive inspections.

Related investigative actions include a determination of the wall thickness of damaged slat cans, and an inspection for clearance between the bottom of the slat can and slat main track. Corrective actions include a blend-out repair or replacement of the slat can with a new or serviceable slat can, proper torque of nuts, and installation of a tapered filler.

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 retain all requirements of AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008), and also would require the actions specified in the service information described previously.

Change to Existing AD (73 FR 15397, March 24, 2008)

This proposed AD would retain all requirements of AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008). Since AD 2008-06-29 was issued, the AD format has been revised, and certain paragraphs have been rearranged. As a result, the corresponding paragraph identifiers have changed in this proposed AD, as listed in the following table:

Revised Paragraph Identifiers

Requirement in AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008)	Corresponding requirement in this proposed AD
paragraph (d)	paragraph (e)
paragraph (e)	paragraph (f)
paragraph (f)	paragraph (g)

In addition, Boeing Commercial Airplanes has received an Organization Designation Authorization (ODA), which replaces the previous designation as a Delegation Option Authorization (DOA) holder. We have revised paragraph (k) of this proposed AD to add delegation of authority to Boeing Commercial Airplanes ODA to approve an alternative method of compliance for certain repairs required by this proposed AD.

Costs of Compliance

We estimate that this proposed AD affects 568 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 of slat track housing [retained actions from existing AD 2008-06-29, Amendment 39-15441, (73 FR 15397, March 24, 2008)]	4 work-hours × $85 per hour = $340 per inspection cycle	$0	$340	$193,120
One-time detailed inspection of slat can [new proposed action]	5 work-hours × $85 per hour = $85	$0	$425	$241,400
Installation of modification [new proposed action]	12 work-hours × $85 per hour = $1,020	$3,124	$4,144	$2,353,792

We have received no definitive data that would enable us to provide a cost estimate 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.

Regulatory Findings

We have 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 that the 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 removing airworthiness directive (AD) 2008-06-29, Amendment 39-15441 ( 73 FR 15397, March 24, 2008), and adding the following new AD:

The Boeing Company: Docket No. FAA-2013-0207; Directorate Identifier 2011-NM-071-AD.

(a) Comments Due Date

The FAA must receive comments on this AD action by April 25, 2013.

(b) Affected ADs

This AD supersedes AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008).

(c) Applicability

This AD applies to all The Boeing Company Model 737-300, -400, and -500 series airplanes, certificated in any category.

(d) Subject

Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 57: Wings.

(e) Unsafe Condition

This AD was prompted by reports of fuel leaking from a puncture in the slat track housing (referred to as “slat can”). We are issuing this AD to prevent loose or missing parts in the main slat track downstop assemblies, which could puncture the slat track housing and result in a fuel leak and consequent fire.

(f) Compliance

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

(g) Retained Inspection of Downstop Assemblies and Corrective Action

This paragraph restates the requirements of paragraph (f) of AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008), with revised service information. At the applicable times specified in Table 1 of paragraph 1.E. of Boeing Service Bulletin 737-57A1301, dated February 5, 2008; or Boeing Alert Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011; except as provided by paragraph (g)(1) of this AD: Do a detailed inspection or borescope inspection of the downstop assemblies on the main tracks of the No. 2, 3, 4, and 5 slats and the inboard track of the No. 1 and 6 slats to verify if any parts are missing, damaged, or installed in the wrong order; and do all the other specified, related investigative, and corrective actions as applicable; by accomplishing all of the applicable actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1301, dated February 5, 2008; or Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011; except as provided by paragraphs (g)(2) and (g)(3) of this AD. Repeat the inspection thereafter at the applicable times specified in Table 1 of paragraph 1.E. of Boeing Service Bulletin 737-57A1301, dated February 5, 2008; or Boeing Alert Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011. Do all applicable related investigative and corrective actions before further flight. As of the effective date of this AD, only Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011, may be used to accomplish the actions required by this paragraph.

(1) Where Boeing Alert Service Bulletin 737-57A1301, dated February 5, 2008, or Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011, specifies counting the compliance time from “the date on the service bulletin,” this AD requires counting the compliance time from April 8, 2008 (the effective date of AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008)).

(2) For airplanes on which any downstop assembly part is missing or damaged, a borescope inspection of the inside of the slat track housing for loose parts and damage to the wall of the slat track housing may be accomplished in lieu of the detailed inspection of the inside of the slat track housing that is specified in Boeing Alert Service Bulletin 737-57A1301, dated February 5, 2008; or Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011. As of the effective date of this AD, only Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011, may be used to do the actions specified in this paragraph.

(3) If any damaged slat track housing is found during any inspection required by paragraph (g) of this AD: Before further flight, repair in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011; replace the slat can with a new slat can having the same part number, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011; or repair the slat can using a method approved in accordance with the procedures specified in paragraph (k) of this AD.

(h) New Detailed Inspection for Foreign Object Debris (FOD)

Within 24 months after the effective date of this AD, do a one-time detailed inspection of the slat can interior to detect FOD, in accordance with Part III of the Accomplishment Instructions of Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011. If any FOD is found, before further flight, remove it, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011.

(i) New Modification and Inspection

Within 72 months or 15,000 flight cycles, whichever occurs first, after the effective date of this AD: Modify the slat track hardware by installing new downstop assembly hardware, and do a detailed inspection for FOD and a one-time inspection for damage to the interior surface of the slat can for the inboard and outboard tracks of slats 2 through 5, and the inboard slats of tracks 1 and 6; and do all applicable related investigative and corrective actions; in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-57A1301, Revision 3, dated August 11, 2011. Do all applicable related investigative and corrective actions before further flight. Accomplishment of the actions required by this paragraph terminates the inspections required by paragraphs (g) and (h) of this AD.

(j) Credit for Previous Actions

This paragraph provides credit for the actions required by paragraphs (g), (h), and (i) of this AD, if those actions were performed before the effective date of this AD using Boeing Alert Service Bulletin 737-57A1301, Revision 1, dated September 24, 2009; or Boeing Alert Service Bulletin 737-57A1301, Revision 2, dated January 17, 2011; which are not incorporated by reference in this AD.

(k) 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: [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, 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.

(4) AMOCs approved previously in accordance with AD 2008-06-29, Amendment 39-15441 (73 FR 15397, March 24, 2008), are approved as AMOCs for the corresponding provisions of this AD.

(l) Related Information

(1) For more information about this AD, contact Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office (ACO), 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: [phone]; fax: [phone]; email: [e-mail].

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; 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.

Issued in Renton, Washington, on February 28, 2013.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.