AD 2001-21-51

[Federal Register Volume 66, Number 211 (Wednesday, October 31, 2001)]
[Rules and Regulations]
[Pages 54918-54920]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 01-27188]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-310-AD; Amendment 39-12474; AD 2001-21-51]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, and -800 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This document publishes in the Federal Register an amendment 
adopting airworthiness directive (AD) 2001-21-51 that was sent 
previously to all known U.S. owners and operators of certain Boeing 
Model 737-600, -700, and -800 series airplanes by individual notices. 
This AD requires a detailed visual inspection for damage of the aft 
pressure bulkhead at body station (BS) 1016 and the forward attachment 
of the vertical fin at body section 48, and corrective action, if 
necessary. This action is prompted by a report of damage to the web of 
the aft pressure bulkhead at BS 1016. The actions specified by this AD 
are intended to find and fix damage of the aft pressure bulkhead at BS 
1016 and the forward attachment of the vertical fin at body section 48, 
which could result in structural failure of the aft pressure bulkhead 
and consequent uncontrolled decompression, or loss of structural 
integrity of the forward support of the vertical fin, loss of the 
vertical fin, and consequent loss of control of the airplane.

DATES: Effective November 5, 2001, to all persons except those persons 
to whom it was made immediately effective by emergency AD 2001-21-51, 
issued October 12, 2001, which contained the requirements of this 
amendment.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of November 5, 2001.
    Comments for inclusion in the Rules Docket must be received on or 
before December 31, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-310-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except 
Federal holidays. Comments may be submitted via fax to (425) 227-1232. 
Comments may also be sent via the Internet using the following address: 
<a href="/cdn-cgi/l/email-protection#1c25317d727131757d6e7f7371717972685c7a7d7d327b736a"><span class="__cf_email__" data-cfemail="e2dbcf838c8fcf8b8390818d8f8f878c96a2848383cc858d94">[email&#160;protected]</span></a>. Comments sent via fax or the Internet must 
contain ``Docket No. 2001-NM-310-AD'' in the subject line and need not 
be submitted in triplicate. Comments sent via the Internet as attached 
electronic files must be formatted in Microsoft Word 97 for Windows or 
ASCII text.
    The applicable service information may be obtained from Boeing 
Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-
2207. This information may be examined at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
Office of the Federal Register, 800 North Capitol Street, NW., suite 
700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Scott Fung, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (425) 227-1221; 
fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: On October 12, 2001, the FAA issued 
emergency AD 2001-21-51, which is applicable to certain Boeing Model 
737-600, -700, and -800 series airplanes.
    The FAA recently received a report indicating that an operator 
found damage to the web of the aft pressure bulkhead at body station 
(BS) 1016 on a Boeing Model 737-700 series airplane. One section of the 
web had two large dents that crossed a radial tearstrap and a crease 
common to one edge. During replacement of the damaged web sections of 
the bulkhead, additional damage to the vertical shear beam web and to 
the skin adjacent to the attachment fittings of the vertical fin at BS 
1016 was found. The vertical shear beam webs are integral to the 
attachment fittings that attach the vertical fin to the fuselage. A 
shimmy event of the main landing gear (MLG) on that airplane also was 
reported, and was so severe that it damaged the MLG and resulted in 
replacement of the right MLG.
    Subsequent to the first report, three other operators reported 
similar damage to the aft pressure bulkhead on other Boeing Model 737-
700 series airplanes, following severe shimmy events which resulted in 
damage to the MLG. A 0.65-inch crack in the aft pressure bulkhead also 
was found on one of the damaged airplanes. Shimmy events are a possible 
cause of the aft pressure bulkhead damage; however, the actual cause is 
undetermined. Hard landings and tail strikes are other possible causes. 
Such damage, if not fixed, could result in structural failure of the 
aft pressure bulkhead and consequent uncontrolled decompression, or 
loss of structural integrity of the forward support of the vertical 
fin, loss of the vertical fin, and consequent loss of control of the 
airplane.
    Boeing Model 737-600 and -800 series airplanes have identical 
structure in the subject area and may also be subject to the same 
unsafe condition described above.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Telegraphic Alert Service 
Bulletin, 737-53A1238, dated October 11, 2001, which describes 
procedures for a detailed visual inspection for damage of the aft 
pressure bulkhead at body station (BS) 1016 and the forward attachment 
of the vertical fin at body section 48. For airplanes on which damage 
is found, the service bulletin describes procedures for doing an 
additional detailed visual inspection of the vertical beam web 
installation. The service bulletin also specifies contacting Boeing for 
repair of any damage found, and reporting inspection results to Boeing.

Explanation of Requirements of the Rule

    Since the unsafe condition described is likely to exist or develop 
on other airplanes of the same type design, the FAA issued emergency AD 
2001-21-51

[[Page 54919]]

to find and fix damage of the aft pressure bulkhead at BS 1016 and the 
forward attachment of the vertical fin at body section 48, which could 
result in structural failure of the aft pressure bulkhead and 
consequent uncontrolled decompression, or loss of structural integrity 
of the forward support of the vertical fin, loss of the vertical fin, 
and consequent loss of control of the airplane. The AD requires a 
detailed visual inspection for damage of the aft pressure bulkhead at 
body station 1016 and the forward attachment of the vertical fin at 
body section 48, and corrective action, if necessary. The actions are 
required to be accomplished in accordance with the service bulletin 
previously described, except as discussed below.

Differences Between This AD and the Telegraphic Service Bulletin

    Although the service bulletin specifies that the manufacturer may 
be contacted for disposition of certain repair conditions, this AD 
requires the repair of those conditions to be accomplished per a method 
approved by the FAA, or per data meeting the type certification basis 
of the airplane approved by a Boeing Company Designated Engineering 
Representative who has been authorized by the Manager, Seattle Aircraft 
Certification Office, to make such findings.
    The service bulletin also specifies doing a detailed visual 
inspection of the aft pressure bulkhead at body station 1016 and the 
forward attachment of the vertical fin at body section 48 for damage, 
within a compliance time that ranges between 5 and 30 days, depending 
upon airplane grouping. However, this AD also requires doing the 
detailed visual inspection before further flight if a severe shimmy 
event that damaged the main landing gear, a hard landing, or a tail 
strike occurs after the effective date of this AD.

Interim Action

    This is considered to be interim action. The inspection reports 
that are required by this AD will enable the FAA to complete its 
evaluation of the need for final action. Once final action is 
developed, approved, and made available, the FAA may consider further 
rulemaking.

Determination of Rule's Effective Date

    Since it was found that immediate corrective action was required, 
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 October 12, 2001, to all known U.S. owners and operators of 
Boeing Model 737-600, -700, and -800 series airplanes; line numbers 1 
through 405 inclusive, and line numbers 466, 585, 590, and 793. 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.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this rule by 
submitting such written data, views, or arguments as they may desire. 
Communications shall identify the Rules Docket number and be submitted 
in triplicate to the address specified under the caption ``ADDRESSES.'' 
All communications received on or before the closing date for comments 
will be considered, and this rule may be amended in light of the 
comments received. Factual information that supports the commenter's 
ideas and suggestions is extremely helpful in evaluating the 
effectiveness of the AD action and determining whether additional 
rulemaking action would be needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the rule. All comments submitted will be 
available, both before and after the closing date for comments, in the 
Rules Docket for examination by interested persons. A report that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2001-NM-310-AD.'' The postcard will be date stamped 
and returned to the commenter.

Regulatory Impact

    The regulations adopted herein 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. Therefore, it 
is determined that this final rule does not have federalism 
implications under Executive Order 13132.
    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 it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, may be obtained from the Rules Docket at the 
location provided under the caption ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (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. Section 39.13 is amended by adding the following new 
airworthiness directive:

2001-21-51  Boeing: Amendment 39-12474. Docket 2001-NM-310-AD.

    Applicability: Model 737-600, -700, and -800 series airplanes; 
line numbers 1 through 405 inclusive, and line numbers 466, 585, 
590, and 793; certificated in any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (f) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.


[[Page 54920]]


    Compliance: Required as indicated, unless accomplished 
previously.
    To find and fix damage of the aft pressure bulkhead at body 
station 1016 and the forward attachment of the vertical fin at body 
section 48, which could result in structural failure of the aft 
pressure bulkhead and consequent uncontrolled decompression, or loss 
of structural integrity of the forward support of the vertical fin, 
loss of the vertical fin, and consequent loss of control of the 
airplane; accomplish the following:

Inspection

    (a) Do a detailed visual inspection for damage of the aft 
pressure bulkhead at body station 1016 and the forward attachment of 
the vertical fin at body section 48, according to Boeing Telegraphic 
Alert Service Bulletin, 737-53A1238, dated October 11, 2001. Except 
as provided by paragraph (b) of this AD, do the inspections at the 
time specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as 
applicable.
    (1) For Group 1 airplanes as identified in paragraph 1.A., 
``Effectivity,'' of the service bulletin: Within 5 days after the 
effective date of this AD.
    (2) For Group 2 airplanes as identified in paragraph 1.A., 
``Effectivity,'' of the service bulletin: Within 10 days after the 
effective date of this AD.
    (3) For Group 3 airplanes as identified in paragraph 1.A., 
``Effectivity,'' of the service bulletin: Within 30 days after the 
effective date of this AD.

    Note 2: For the purposes of this AD, a detailed visual 
inspection is defined as: ``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.''

    (b) For airplanes identified in paragraphs (b)(1) and (b)(2) of 
this AD: Do the inspection at the time specified in those 
paragraphs, as applicable.
    (1) For Group 2 or Group 3 airplanes on which a severe shimmy 
event that damaged the main landing gear before the effective date 
of this AD, or on which a hard landing or a tail strike occurred 
before the effective date of this AD: Do the inspection required by 
paragraph (a) of this AD at the time specified in paragraph (a)(1) 
of this AD.
    (2) For Group 3 airplanes on which a shimmy event that damaged 
the aircraft interior or the flaps occurred before the effective 
date of this AD: Do the inspection required by paragraph (a) of this 
AD at the time specified in paragraph (a)(2) of this AD.
    (c) Do the inspection required by paragraph (a) of this AD 
before further flight after any of the following events occurring 
after the effective date of this AD: A severe shimmy event that 
damaged the main landing gear, a hard landing, or a tail strike.

Corrective Action

    (d) If any damage is found during the inspection required by 
this AD, before further flight, do a detailed visual inspection of 
the vertical beam web installation for damage, according to Boeing 
Telegraphic Alert Service Bulletin, 737-53A1238, dated October 11, 
2001. If any damage is found, before further flight, repair all 
damage per a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA; or per data meeting the type 
certification basis of the airplane approved by a Boeing Company 
Designated Engineering Representative who has been authorized by the 
Manager, Seattle ACO, to make such findings. For a repair method to 
be approved by the Manager, Seattle ACO, as required by this 
paragraph, the approval letter must specifically reference this AD.

Reporting Requirement

    (e) Submit a report of inspection findings (both positive and 
negative) to the Manager, Seattle ACO, FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; 
fax (425) 227-1181; at the applicable time specified in paragraph 
(e)(1) or (e)(2) of this AD. The report must include the following: 
The approximate date of inspection; whether the shimmy dampers were 
installed subsequent to aircraft delivery; a description of any 
structural damage found and its location, as well as the extent and 
depth of the damage, or whether structural damage was NOT found; 
whether any shimmy event, hard landing, engine-out, or tail strike 
has occurred; the airplane serial number; and the number of landings 
and flight hours on the airplane. Information collection 
requirements contained in this regulation have been approved by the 
Office of Management and Budget (OMB) under the provisions of the 
Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et seq.) and have 
been assigned OMB Control Number 2120-0056.
    (1) For airplanes on which the inspection is accomplished after 
the effective date of this AD: Submit the report within 5 days after 
performing the inspection required by paragraph (a) of this AD.
    (2) For airplanes on which the inspection has been accomplished 
prior to the effective date of this AD: Submit the report within 5 
days after the effective date of this AD.

Alternative Methods of Compliance

    (f) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Seattle ACO, FAA. Operators shall 
submit their requests through an appropriate FAA Principal 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Special Flight Permits

    (g) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.

Incorporation by Reference

    (h) Except as provided by paragraph (d) of this AD, the actions 
shall be done in accordance with Boeing Telegraphic Alert Service 
Bulletin, 737-53A1238, dated October 11, 2001. This incorporation by 
reference was approved by the Director of the Federal Register in 
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, 
Seattle, Washington 98124-2207. Copies may be inspected at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the Office of the Federal Register, 800 North 
Capitol Street, NW., suite 700, Washington, DC.
    (i) This amendment becomes effective on November 5, 2001, to all 
persons except those persons to whom it was made immediately 
effective by emergency AD 2001-21-51, issued on October 12, 2001, 
which contained the requirements of this amendment.

    Issued in Renton, Washington, on October 22, 2001.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-27188 Filed 10-30-01; 8:45 am]
BILLING CODE 4910-13-P