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Proposed Rule

Airworthiness Directives; Boeing Model 737-100, -200, and -200C Series Airplanes

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Information about this document as published in the Federal Register.

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AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 737-100, -200, and -200C series airplanes. This proposed AD would require a one-time detailed inspection for cracking of the lugs of the inboard attach fittings of the wing leading edge slat tracks at slat numbers 2 and 5; prior or concurrent actions for certain airplanes; repetitive high-frequency eddy current (HFEC) inspections for cracking of the lug surfaces of those inboard attach fittings if necessary; and replacement of the attach fittings with new, improved fittings. This proposed AD is prompted by reports of damage to the lugs of certain inboard attach fittings of the leading edge slat tracks. We are proposing this AD to prevent a lifted slat, which, if the airplane performs any non-normal maneuver during takeoff or landing at very high angles of attack, could lead to the loss of the slat and reduced control of the airplane.

DATES:

We must receive comments on this proposed AD by June 23, 2005.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed 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: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, Washington, DC 20590.
  • By fax: (202) 493-2251.
  • Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, 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, P.O. Box 3707, Seattle, Washington 98124-2207. Start Printed Page 24336

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov, or at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC. This docket number is FAA-2005-21138; the directorate identifier for this docket is 2004-NM-131-AD.

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FOR FURTHER INFORMATION CONTACT:

Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6440; fax (425) 917-6590.

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SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any written relevant data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2005-21138; Directorate Identifier 2004-NM-131-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed AD in light of those comments.

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 proposed 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 can review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.

Examining the Docket

You can examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.

Discussion

We have received reports of damage to the lugs of the inboard attach fittings of the wing leading edge slat tracks at slat numbers 2 and 5 on several Boeing Model 737-100, -200, and -200C series airplanes. Two reports addressed damage that occurred during takeoff and four reports addressed damage that occurred during flight. The other damaged fittings were found during routine maintenance inspections. In most of the reports, the lugs of the fittings had fractured or cracked. Both lugs of one fitting had fractured and were completely separated at the slat-to-track attach bolt. The auxiliary track was also lifted and there was damage to the upper skin of the leading edge cavity on each side. Boeing analysis has determined this fitting damage was due to cyclic fatigue. This condition, if not corrected, could result in a lifted slat, which, if the airplane performs any non-normal maneuver during takeoff or landing at very high angles of attack, could lead to loss of the slat and reduced control of the airplane.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 737-57-1273, Revision 2, dated October 30, 2003. The service bulletin describes procedures for a one-time detailed visual inspection for cracking of the lugs of the inboard attach fittings at slat tracks 2 and 5 of the wing leading edge, repetitive high-frequency eddy current (HFEC) inspections for cracking of the lug surfaces of those inboard attach fittings, and replacement of the aluminum inboard attach fittings with new, improved steel inboard attach fittings. Replacement of any aluminum inboard attach fitting with a new, improved steel inboard attach fitting eliminates the need for the one-time detailed inspection and the repetitive HFEC inspections for that fitting. Accomplishing the actions specified in the service bulletin is intended to adequately address the unsafe condition.

Service Bulletin 737-57-1273, Revision 2, specifies prior accomplishment of portions of Boeing Service Bulletin 737-57-1080, Revision 3, dated September 24, 1992 (applicable to Group 2 airplanes only as listed in Service Bulletin 737-57-1273). Among other things, Service Bulletin 737-57-1080, Revision 3, Figure 3, describes procedures for inspecting the slat tab support clip on slats 2 and 5 for interference with the slat track inboard attach fittings and trimming the subject slat tab support clips to eliminate any such interference.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD, which would require a one-time detailed inspection for cracking of the lugs of the inboard attach fittings at slat tracks 2 and 5 of the wing leading edge, related investigative actions, trimming the slat tab support clip on slats 2 and 5 to eliminate any interference with the slat track inboard attach fittings if necessary, and replacing the attach fittings with new, improved fittings. Replacement of any aluminum inboard attach fitting with a new, improved steel inboard attach fitting terminates the one-time detailed inspection and the repetitive HFEC inspections for that fitting. The proposed AD would require you to use the service information described previously to perform these actions, except as discussed under “Clarification of Inspection Terminology.”

Clarification of Inspection Terminology

In this proposed AD, the “detailed visual inspection” specified in the Boeing service bulletin is referred to as a “detailed inspection.” We have included the definition for a detailed inspection in the proposed AD.

Costs of Compliance

This proposed AD would affect about 909 airplanes worldwide. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

ActionWork hoursAverage labor rate per hourParts costCost per airplaneNumber of U.S.-registered airplanesFleet cost
Detailed inspection1$65None$65522$33,930
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HFEC Inspection465None230, per inspection cycle.522120,060, per inspection cycle.
Replace fitting265$1,6741,804522941,688

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 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. See the ADDRESSES section for a location to examine the regulatory evaluation.

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List of Subjects in 14 CFR Part 39

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The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

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[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2005-21138; Directorate Identifier 2004-NM-131-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by June 23, 2005.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 737-100, -200, and -200C series airplanes; line numbers 1 through 1585 inclusive; certificated in any category.

Unsafe Condition

(d) This AD was prompted by reports of damage to the lugs of certain inboard attach fittings of the leading edge slat tracks. We are issuing this AD to prevent a lifted slat, which, if the airplane performs any non-normal maneuver during takeoff or landing at very high angles of attack, could lead to the loss of the slat and reduced control of the airplane.

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.

Service Bulletin Reference

(f) The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-57-1273, Revision 2, dated October 30, 2003; unless otherwise specified in this AD.

Inspections

(g) Prior to the accumulation of 7,000 total flight cycles or within 12 months after the effective date of this AD, whichever occurs later, perform a one-time detailed inspection for cracking and damage of the inboard attach fittings at slats 2 and 5 of the wing leading edge in accordance with the Accomplishment Instructions of the service bulletin.

Note 1:

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

(1) If any crack or damage is found, replace the cracked inboard attach fitting in accordance with paragraph (h) of this AD.

(2) If no crack or damage is found, within 4,500 flight cycles or 18 months after the detailed inspection required by paragraph (g) of this AD, whichever occurs first, perform a high-frequency eddy current (HFEC) inspection for cracking of the lugs of the inboard attach fittings in accordance with the Accomplishment Instructions of the service bulletin. If no crack is found, repeat the HFEC inspection at intervals not to exceed 4,500 flight cycles.

Replacement of Fittings

(h) Replace the aluminum inboard attach fittings with new, improved steel fittings at the applicable compliance time in paragraph (h)(1) or (h)(2) of this AD in accordance with the Accomplishment Instructions of the service bulletin. Replacement of any aluminum fitting with a new, improved steel fitting terminates the one-time detailed inspection and the repetitive HFEC inspections required by paragraph (g) of this AD for that fitting.

(1) If any crack or damage is found during any inspection required by paragraphs (g) or (i) of this AD, before further flight.

(2) If no crack or damage is found during any inspection required by paragraph (g) or (i) of this AD, within 30,000 flight cycles or within 120 months after the effective date of this AD, whichever occurs first.

Concurrent Service Bulletin

(i) For airplanes listed in Group 2 of Boeing Special Attention Service Bulletin 737-57-1273, Revision 2: Prior to or during the one-time detailed inspection for cracking or damage required by paragraph (g) of this AD or during replacement of the fitting required by paragraph (h) of this AD, whichever occurs first, perform a detailed inspection on slats 2 and 5 for interference of the slat tab Start Printed Page 24338support clips with the slat track attach fittings and trim the support clips to eliminate any interference with the attach fittings as applicable; in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-57-1080, Revision 3, Figure 3, dated September 24, 1992; and replace any cracked or damaged aluminum attach fitting with a new, improved steel fitting in accordance with paragraph (h) of this AD.

Actions Accomplished Per Previous Issue of Service Bulletin

(j) Actions accomplished before the effective date of this AD in accordance with Boeing Service Bulletin 737-57-1080, dated September 10, 1973; Boeing Service Bulletin 737-57-1080, Revision 1, dated February 25, 1983; and Boeing Service Bulletin 737-57-1080, Revision 2, dated August 24, 1989; are considered acceptable for compliance with the corresponding actions specified in paragraph (i) of this AD.

Alternative Methods of Compliance (AMOCs)

(k)(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) 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 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.

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Issued in Renton, Washington, on April 29, 2005.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 05-9187 Filed 5-6-05; 8:45 am]

BILLING CODE 4910-13-P