[Federal Register Volume 70, Number 88 (Monday, May 9, 2005)]
[Proposed Rules]
[Pages 24335-24338]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-9187]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2005-21138; Directorate Identifier 2004-NM-131-AD]
RIN 2120-AA64


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

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

ACTION: Notice of proposed rulemaking (NPRM).

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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.

[[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.

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.

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
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                                                                                                                 Number of U.S.-
               Action                   Work    Average labor         Parts cost           Cost per airplane       registered           Fleet cost
                                       hours    rate per hour                                                       airplanes
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Detailed inspection.................        1             $65  None...................  $65....................             522  $33,930

[[Page 24337]]

 
HFEC Inspection.....................        4              65  None...................  230, per inspection                 522  120,060, per inspection
                                                                                         cycle..                                  cycle.
Replace fitting.....................        2              65  $1,674.................  1,804..................             522  941,688
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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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, 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.


Sec.  39.13  [Amended]

    2. The FAA amends Sec.  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

[[Page 24338]]

support 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.

    Issued in Renton, Washington, on April 29, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-9187 Filed 5-6-05; 8:45 am]
BILLING CODE 4910-13-P