[Federal Register Volume 65, Number 153 (Tuesday, August 8, 2000)]
[Rules and Regulations]
[Pages 48358-48360]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-19672]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-183-AD; Amendment 39-11844; AD 2000-15-12]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Boeing Model 737-100, -200, and -200C series 
airplanes. This action requires inspections of a certain component, and 
corrective action, if necessary. This action is necessary to detect and 
correct stress corrosion cracking in the front spar of the center 
section of the horizontal stabilizer, which could result in structural 
failure of the horizontal stabilizer and loss of control of the 
airplane. This action is intended to address the identified unsafe 
condition.

DATES: Effective August 23, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 23, 2000.
    Comments for inclusion in the Rules Docket must be received on or 
before October 10, 2000.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-183-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056. Comments may be inspected at this 
location between 9 a.m. and 3 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: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-183-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 service information referenced in this AD 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: Nenita Odesa, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (425) 227-2557; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received reports indicating 
that, during regular maintenance, operators found stress corrosion 
cracks in the front spar of the center section of the horizontal 
stabilizer on two Boeing Model 737-100 and -200 series airplanes. The 
subject airplanes had 42,700 and 67,100 flight cycles. The front spar 
is made from 7079-T6 aluminum, a material that was used for this 
component until the manufacturer determined that the material is 
susceptible to stress corrosion cracking. Cracks in the front spar will 
decrease the structural strength of the center section of the 
horizontal stabilizer. This condition, if not corrected, could result 
in structural failure of the horizontal stabilizer and loss of control 
of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
737-55A1071, dated February 24, 2000, which describes procedures for 
repetitive detailed visual inspections to detect cracking in the front 
spar of the center section of the horizontal stabilizer, and corrective 
actions, if necessary. If cracking is within certain limits, corrective 
actions involve rework of the front spar fitting that includes removing 
damaged material, performing a high frequency eddy current inspection 
to detect cracking, and shot

[[Page 48359]]

peening the damaged area. If cracking is outside the limits, the alert 
service bulletin specifies to contact the manufacturer for repair 
instructions. Accomplishment of the actions specified in the service 
bulletin is intended to adequately address the identified unsafe 
condition.

Explanation of the Requirements of the Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other airplanes of the same type design, this AD is 
being issued to detect and correct stress corrosion cracking in the 
front spar of the center section of the horizontal stabilizer, which 
could result in structural failure of the horizontal stabilizer and 
loss of control of the airplane. This AD requires accomplishment of the 
actions specified in the alert service bulletin described previously, 
except as discussed below.

Differences Between Alert Service Bulletin and This AD

    Operators should note that, although the alert 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 in accordance with a method approved by 
the FAA, or in accordance with data meeting the type certification 
basis of the airplane approved by a Boeing Company Designated 
Engineering Representative who has been authorized by the FAA to make 
such findings.
    The service bulletin also provides for a terminating action by 
replacing the front spar with a spar made from a 7050 or 7075 aluminum 
forging. However, this AD does not authorize the terminating action 
proposed in the service bulletin.

Determination of Rule's Effective Date

    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

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.
    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the AD is 
being requested.
     Include justification (e.g., reasons or data) for each 
request.
    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 2000-NM-183-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:

2000-15-12  Boeing: Amendment 39-11844. Docket 2000-NM-183-AD.

    Applicability: Model 737-100, -200, and -200C series airplanes; 
line numbers 1 through 315 inclusive, 323, and 324; 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 (d) 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.

    Compliance: Required as indicated, unless accomplished 
previously.
    To detect and correct stress corrosion cracking in the front 
spar of the center section of the horizontal stabilizer, which could 
result in structural failure of the horizontal stabilizer and loss 
of control of the airplane, accomplish the following:

Repetitive Detailed Visual Inspections

    (a) Within 90 days after the effective date of this AD, perform 
a detailed visual inspection to detect cracks in the front spar of 
the center section of the horizontal stabilizer, in accordance with 
Boeing Alert Service Bulletin 737-55A1071, dated

[[Page 48360]]

    February 24, 2000. Thereafter, repeat the inspection twice more 
at intervals not to exceed 200 days, and thereafter at intervals not 
to exceed 24 months or 4,000 flight cycles, whichever occurs first.

    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.''

Rework

    (b) Except as required by paragraph (c) of this AD, if any crack 
is detected during any inspection required by paragraph (a) of this 
AD, prior to further flight, accomplish rework of the front spar of 
the center section of the horizontal stabilizer (including removing 
damaged material, accomplishing a high frequency eddy current 
inspection to detect cracking, and shot peening the damaged area), 
in accordance with Boeing Alert Service Bulletin 737-55A1071, dated 
February 24, 2000.

Cracking Outside the Limits Specified in the Alert Service Bulletin

    (c) If any crack that is outside the limits specified in the 
alert service bulletin is detected during any inspection required by 
paragraph (a) of this AD, prior to further flight, repair in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate; or 
in accordance with 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.

Alternative Methods of Compliance

    (d) 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. 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

    (e) 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

    (f) Except as provided by paragraph (c) of this AD, the actions 
shall be done in accordance with Boeing Alert Service Bulletin 737-
55A1071, dated February 24, 2000. 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.

Effective Date

    (g) This amendment becomes effective on August 23, 2000.

    Issued in Renton, Washington, on July 28, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-19672 Filed 8-7-00; 8:45 am]
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