E7-18436. Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, -900, and -900ER Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Final rule; request for comments.

SUMMARY:

This document publishes in the Federal Register an amendment adopting airworthiness directive (AD) 2007-18-52 that was sent previously to all known U.S. owners and operators of Boeing Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes by individual notices. This AD requires repetitive detailed inspections of the slat track downstop assemblies to verify that proper hardware is installed, one-time torquing of the nut and bolt, and corrective actions if necessary. This AD is prompted by reports of parts coming off the main slat track downstop assemblies. We are issuing this AD to detect and correct loose or missing parts from the main slat track downstop assemblies, which could result in a fuel leak and consequent fire.

DATES:

This AD becomes effective September 26, 2007 to all persons except those persons to whom it was made immediately effective by emergency AD 2007-18-52, issued August 28, 2007, which contained the requirements of this amendment.

We must receive comments on this AD by November 20, 2007.

ADDRESSES:

Use one of the following addresses to submit comments on this AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• 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.
• Fax: [phone].
• Hand Delivery: Room W12-140 on the ground floor of the West Building, 1200 New Jersey Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for service information identified in this AD.

FOR FURTHER INFORMATION CONTACT:

Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

On August 28, 2007, we issued emergency AD 2007-18-52, which applies to all Boeing Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. That emergency AD superseded emergency AD 2007-18-51, described below.

Background

On August 25, 2007, we issued emergency AD 2007-18-51 for all Boeing Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. That AD requires repetitive detailed inspections of the main slat track downstop assemblies to verify that proper hardware is installed, one-time torquing of the nut and bolt, and corrective actions if necessary. Corrective actions include installing a new or serviceable part; and doing a detailed inspection of the inside of the slat can for foreign object debris (FOD) and damage, and removing any FOD and repairing damage that is found.

That AD resulted from reports of parts of the main slat track downstop assembly coming off the main slat track. In one case, a nut fell into the slat track housing (referred to as “slat can”) and, during a subsequent slat retraction, the track made contact with the nut, pushing it into the wall of the can and puncturing it. That operator reported finding fuel leaking from the drain hole in the slat track housing at the No. 5 slat track position. In another case, an initial investigation revealed that following retraction of the slats after landing on a Model 737-800 airplane, loose parts of the main slat track downstop assembly punctured the slat can, which resulted in a fuel leak and a fire that ultimately destroyed the airplane. We issued that AD to detect and correct loose or missing parts from the main slat track downstop assemblies, which could result in a fuel leak and consequent fire.

Actions Since Issuance of Emergency AD 2007-18-51

Since the issuance of emergency AD 2007-18-51, we have received additional reports of parts coming off the main slat track downstop assemblies. In these cases, the parts were found in the bottom of the slat track housing (“slat can”). Additionally, in one case, the slat can was damaged.

Based on this new information, we find that the 24-day compliance time specified in emergency AD 2007-18-51 for accomplishing the detailed inspection of each main slat track downstop assembly to verify proper installation of the slat track hardware is not adequate to address the unsafe condition. We have determined that the appropriate compliance time for this inspection is 10 days after receipt of emergency AD 2007-18-52. In addition, we have determined that an inspection using borescope techniques in lieu of a detailed inspection is acceptable.

Further, we have determined that by performing the initial detailed or borescope inspection within the reduced compliance time of 10 days, the compliance time for torquing the nut and bolt can remain at 24 days after receipt of emergency AD 2007-18-51.

FAA's Determination and Requirements of This AD

Since the unsafe condition described is likely to exist or develop on other airplanes of the same type design, we issued emergency AD 2007-18-52 to detect and correct loose or missing parts from the main slat track downstop assemblies, which could result in a fuel leak and consequent fire.

This AD supersedes emergency AD 2007-18-51, which required repetitive detailed inspections of the main slat track downstop assemblies to verify that proper hardware is installed, one-time torquing of the nut and bolt, and corrective actions if necessary. Corrective actions include installing a new or serviceable part; and doing a detailed inspection of the inside of the slat can for foreign object debris (FOD) and damage, and removing any FOD and repairing damage that is found.

This AD continues to require the same actions as emergency AD 2007-18-51, but reduces the compliance time for the initial detailed inspection of each main slat track downstop assembly to verify proper installation of the slat track hardware from 24 days after receipt of emergency AD 2007-18-51 to 10 days after receipt of this new AD. This AD also provides an additional inspection method (using borescope techniques) in lieu of the detailed inspection.

Clarification of Determining Proper Installation of Hardware

Operators should note that it was not our intent that the hardware for the main slat track downstop assemblies be disassembled to determine proper installation of the sleeve. Proper installation of the sleeve need not be confirmed, and the stop location part may be installed on either the inboard or the outboard side of the slat track. Disassembling the parts provides additional opportunities for introducing the unsafe condition addressed in this AD. Therefore, we have revised paragraph (f) of this AD accordingly.

Clarification of Reference to Boeing Multi Operator Message

Paragraph (f)(1) of emergency AD 2007-18-51 identified “Boeing Correspondence (Multi Operator Message) Service Request ID 1-523812011, issued August 25, 2007,” as one approved method for verifying proper installation; installing a new or serviceable part; and inspecting for damage and FOD, and removing FOD and repairing damage. This AD identifies that document correctly as “Boeing Multi Operator Message Number 1-523812011-1, issued August 25, 2007.”

Since the issuance of emergency AD 2007-18-51, Boeing has issued Boeing Multi Operator Message Number 1-527463441-1, issued August 28, 2007. We have referenced that document in this AD as an additional approved method for doing the specified actions.

We found that immediate corrective action was required; therefore, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual notices issued on August 28, 2007, to all known U.S. owners and operators of Boeing Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.

Interim Action

We consider this AD interim action. If final action is later identified, we might consider further rulemaking then.

Comments Invited

This AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed in the ADDRESSES section. Include “Docket No. FAA-2007-29089, Directorate Identifier 2007-NM-215-AD,” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD that might suggest a need to modify it.

We will post all comments we receive, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Examining the Docket

You may examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Operations office (telephone [phone]) is located on the ground level of the West Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

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 AD will not have federalism implications under Executive Order 13132. This AD will 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.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a “significant regulatory action” under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If this emergency regulation is later deemed significant under DOT Regulatory Policies and Procedures, we will prepare a final regulatory evaluation and place it in the AD Docket. See the ADDRESSES section for a location to examine the regulatory evaluation, if filed.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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):

2007-18-52 Boeing: Amendment 39-15197. Docket No. FAA-2007-29089; Directorate Identifier 2007-NM-215-AD.

Effective Date

(a) This AD becomes effective September 26, 2007, to all persons except those persons to whom it was made immediately effective by emergency AD 2007-18-52, issued on August 28, 2007, which contained the requirements of this amendment.

Affected ADs

(b) This AD supersedes emergency AD 2007-18-51, issued August 25, 2007.

Applicability

(c) This AD applies to all Boeing Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from additional reports of parts coming off the main slat track downstop assemblies. We are issuing this AD to detect and correct loose or missing parts from the main slat track downstop assemblies, which could result in a fuel leak and consequent fire.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Note 1:

Paragraph (f) of this AD merely restates the requirements of paragraph (f)(1) of AD 2007-18-51. As allowed by the phrase, “unless the actions have already been done,” if the applicable initial inspections required by paragraph (f)(1) of AD 2007-18-51 have already been done, this AD does not require that those inspections be repeated until the repetitive interval of 3,000 flight cycles.

Repetitive Detailed Inspections: New Initial Compliance Time

(f) Within 10 days after the effective date of this AD: Do a detailed inspection or a borescope inspection of each main slat track downstop assembly to verify proper installation of the slat track hardware (i.e., the bolt, washers, downstops, stop location, and nut shown in Figure 1 of Boeing Service Letter 737-SL-57-084-B, dated July 10, 2007, and in this AD). Proper installation of the sleeve need not be confirmed, and the stop location part may be installed on either the inboard or the outboard side of the slat track. If any part is missing or is installed improperly, before further flight, install a new or serviceable part using a method approved in accordance with the procedures specified in paragraph (h) of this AD; and do a detailed inspection of the inside of the slat can for foreign object debris (FOD) and damage. Before further flight, remove any FOD found and repair any damage found using a method approved in accordance with the procedures specified in paragraph (h) of this AD. Using Boeing Multi Operator Message Number 1-523812011-1, issued August 25, 2007; or 1-527463441-1, issued August 28, 2007; is one approved method for verifying proper installation; installing a new or serviceable part; and inspecting for damage and FOD, and removing FOD and repairing damage. Repeat the actions required by paragraph (f) of this AD thereafter at intervals not to exceed 3,000 flight cycles.

Note 2:

Paragraph (g) of this AD merely restates the requirements of paragraph (f)(2) of AD 2007-18-51. As allowed by the phrase, “unless the actions have already been done,” if the torque application required by paragraph (f)(2) of AD 2007-18-51 has already been done, this AD does not require that the torque application be repeated.

One-Time Torquing

(g) Within 24 days after receipt of AD 2007-18-51: Apply a torque between 50 to 80 inch-pounds to the nut. The bolt head must be held with the torque applied to the nut.

Note 3:

For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”

Alternative Methods of Compliance (AMOCs)

(h)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(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 an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who 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 2007-18-51 are approved as AMOCs for the corresponding provisions of this AD.

Material Incorporated by Reference

(i) None.

Issued in Renton, Washington, on September 10, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.