2010-187. Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, -900, and -900ER Series Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to all Boeing Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. The existing AD currently 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 proposed AD would also require replacing the hardware of the down stop assembly with new hardware of the down stop assembly, doing a detailed inspection or a borescope inspection of the slat cans on each wing and the lower rail of the slat main tracks for debris, replacing the bolts of the aft side guide with new bolts, and removing any debris found in the slat can. This proposed AD also would remove airplanes from the applicability. This proposed AD results from reports of parts coming off the main slat track downstop assemblies. We are proposing this AD to prevent loose or missing parts from the main slat track downstop assemblies from falling into the slat can and causing a puncture, which could result in a fuel leak and consequent fire.

DATES:

We must receive comments on this proposed AD by February 25, 2010.

ADDRESSES:

You may send comments 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: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, 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]; e-mail [e-mail]; 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 or 425-227-1152.

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 (telephone [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, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

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-2009-1253; Directorate Identifier 2009-NM-080-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 August 28, 2007, we issued AD 2007-18-52, amendment 39-15197 (72 FR 53928, September 21, 2007), for all Boeing Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. That AD superseded emergency AD 2007-18-51 to require a shorter compliance time for the actions originally required in emergency AD 2007-18-51. AD 2007-18-52 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. That AD resulted from reports of parts coming off the main slat track downstop assemblies. We issued that AD to detect and correct loose or missing parts from the main slat track downstop assemblies from falling into the slat can and causing a puncture, which could result in a fuel leak and consequent fire.

Actions Since Existing AD Was Issued

The preamble to AD 2007-18-52 explains that we consider the requirements “interim action” and were considering further rulemaking. Since we issued AD 2007-18-52, Boeing has modified the hardware of the down stop assembly and the bolts of the aft side guide. The new modifications would terminate the actions required in AD 2007-18-52. We now have determined that further rulemaking is indeed necessary, and this proposed AD follows from that determination.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 737-57A1302, dated December 15, 2008. The service bulletin describes procedures for replacing the hardware of the down stop assembly with new hardware, doing a detailed inspection or a borescope inspection of the slat cans on each wing and the lower rail of the slat main tracks for debris, replacing the bolts of the aft side guide with new bolts, and removing any debris found in the slat can.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to develop on other airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 2007-18-52 and would retain the requirements of the existing AD. This proposed AD would also require accomplishing the actions specified in the Relevant Service Information described previously. The proposed AD would also remove certain airplanes having line numbers 2700 and on from the applicability; these airplanes have a design change incorporated during production, which is an equivalent change to the actions described in the Relevant Service Information.

Change to Existing AD

This proposed AD would retain all requirements of AD 2007-18-52. 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 2007-18-52	Corresponding requirement in this proposed AD
paragraph (f)	paragraph (g).
paragraph (g)	paragraph (h).

Costs of Compliance

There are about 2,699 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Parts	Cost per airplane	Number of U.S.- registered airplanes	Fleet cost
Inspection and Torquing (required by AD 2007-18-52)	8	$80	$0	$640, per inspection cycle	853	$545,920, per inspection cycle.
Inspection and Modification (new proposed actions)	18	80	5,388	6,828	853	5,824,284.

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); 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.

We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

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 amendment 39-15197 (72 FR 53928, September 21, 2007) and adding the following new AD:

Boeing: Docket No. FAA-2009-+++++; Directorate Identifier 2009-NM-080-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by February 25, 2010.

Affected ADs

(b) This AD supersedes AD 2007-18-52.

Applicability

(c) This AD applies to Boeing Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 737-57A1302, dated December 15, 2008.

Subject

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

Unsafe Condition

(e) This AD results from reports of parts coming off the main slat track downstop assemblies. The Federal Aviation Administration is issuing this AD to prevent loose or missing parts from the main slat track downstop assemblies from falling into the slat can and causing a puncture, which could result in a fuel leak and consequent fire.

Compliance

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

Restatement of AD 2007-18-52 With No Changes

Note 1:

Paragraph (g) of this AD merely restates the requirements of paragraph (f)(1) of emergency AD 2007-18-51 (which was superseded by AD 2007-18-52). As allowed by the phrase, “unless the actions have already been done,” if the applicable initial inspections required by paragraph (f)(1) of emergency 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

(g) Within 10 days after September 26, 2007 (the effective date of AD 2007-18-52): 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 (j) 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 (j) of this AD. Verify proper installation; install a new or serviceable part; and inspect for damage and FOD, and remove FOD and repair damage, in accordance with a method by approved by the Manager, Seattle Aircraft Certification Office, FAA; or in accordance with Boeing Multi Operator Message Number 1-523812011-1, issued August 25, 2007; or 1-527463441-1, issued August 28, 2007. Repeat the actions required by paragraph (g) of this AD thereafter at intervals not to exceed 3,000 flight cycles.

Note 2:

Paragraph (h) of this AD merely restates the requirements of paragraph (f)(2) of emergency 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 emergency 2007-18-51 has already been done, this AD does not require that the torque application be repeated.

One-Time Torquing

(h) Within 24 days after receipt of emergency 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.”

New Requirements of This AD

Modification and Inspection

(i) Within 36 months after the effective date of this AD: Replace the hardware of the down stop assembly with new hardware, do a detailed inspection or a borescope inspection of the slat cans on each wing and the lower rail of the slat main tracks for debris, and replace the bolts of the aft side guide with new bolts, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1302, dated December 15, 2008 (“the service bulletin”); except, where the service bulletin specifies to replace the slat main track or contact Boeing for further repair instructions if the hole diameter is greater than 0.5005 inch, before further flight replace the slat main track in accordance with the service bulletin or repair using a method approved in accordance with the procedures specified in paragraph (j) of this AD. If debris is found during any inspection required by this AD, before further flight, remove the debris in accordance with the Accomplishment Instructions of the service bulletin. Doing the actions required by paragraph (i) of this AD terminates the actions required by paragraphs (g) and (h) of this AD.

Alternative Methods of Compliance

(j)(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. Send information to Attn: Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]. Or, e-mail information to [e-mail].

(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 principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

(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 2007-18-52 are approved as AMOCs for the corresponding provisions of this AD.

Issued in Renton, Washington, on December 23, 2009.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.