[Federal Register Volume 67, Number 81 (Friday, April 26, 2002)]
[Rules and Regulations]
[Pages 20626-20627]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-10249]



[[Page 20626]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2002-NM-109-AD; Amendment 39-12727; AD 2002-08-52]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, and -700C 
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) 2002-08-52, that was sent 
previously to all known U.S. owners and operators of all Boeing Model 
737-600, -700, and -700C series airplanes by individual notices. This 
AD requires revising the Airplane Flight Manual (AFM) to prohibit 
operating the airplane at speeds in excess of 300 knots indicated 
airspeed (KIAS) with speedbrakes extended. This AD also provides for 
optional terminating action for the AFM revision. This action is 
prompted by a report indicating that severe vibration of the horizontal 
stabilizer occurred on a Boeing Model 737-700 series airplane. The 
actions specified by this AD are intended to prevent severe vibration 
of the elevator and elevator tab assembly following deployment of the 
speedbrakes, which, if not corrected, could result in severe damage to 
the horizontal stabilizer, followed by possible loss of controllability 
of the airplane.

DATES: Effective May 1, 2002, to all persons except those persons to 
whom it was made immediately effective by emergency AD 2002-08-52, 
issued April 11, 2002, which contained the requirements of this 
amendment.
    Comments for inclusion in the Rules Docket must be received on or 
before June 25, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2002-NM-109-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. 2002-NM-109-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.
    Information pertaining to this amendment may be examined at the 
FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Nancy H. Marsh, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2028; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: On April 11, 2002, the FAA issued emergency 
AD 2002-08-52, which is applicable to all Boeing Model 737-600, -700, 
and -700C series airplanes.

Background

    The FAA received a report indicating that severe vibration of the 
horizontal stabilizer occurred on a Boeing Model 737-700 series 
airplane. The airplane was operating at an altitude of 19,500 feet and 
an airspeed of 315 knots indicated airspeed (KIAS). The high frequency 
vibration was initiated by deployment of the speedbrakes during descent 
of the airplane. The vibration continued until the airspeed was reduced 
to 285 KIAS, even though the speedbrakes were retracted. The airplane 
landed without further incident. The FAA and the manufacturer have 
determined that the vibration was due to a ``limit cycle oscillation'' 
of the elevator and elevator tab assembly attached to the horizontal 
stabilizer. Such oscillation was caused by a buffeting flow over the 
surface of the horizontal stabilizer, which occurred following 
deployment of the speedbrakes.
    Results of post-event analysis and investigation indicate that 
severe vibration of the elevator and elevator tab assembly following 
deployment of the speedbrakes, if not corrected, could result in severe 
damage to the horizontal stabilizer, followed by possible loss of 
controllability of the airplane.

Other Similar Models

    The elevator tabs on Model 737-600 and -700C series airplanes are 
identical to those on Model 737-700 series airplanes. Therefore, those 
Model 737-600 and -700C series airplanes may be subject to the same 
unsafe condition revealed on Model 737-700 series airplanes.
    In addition, operators should note that modified elevator tabs have 
already been installed on Model 737-900 series airplanes.

Other Relevant Rulemaking

    The FAA previously issued AD 2001-12-51, amendment 39-12294 (66 FR 
34094, June 27, 2001), applicable to all Boeing Model 737-800 series 
airplanes. That AD was issued to ensure that the flight crew is advised 
of the potential hazard associated with extending the speedbrakes at 
speeds in excess of 300 KIAS. That AD requires revising the Airplane 
Flight Manual to prohibit operating the airplane at speeds in excess of 
300 KIAS with speedbrakes extended. That AD also provides for optional 
terminating action for the AFM revision.

FAA's Conclusions

    In light of this information, the FAA finds that certain new 
limitations should be included in the FAA-approved Airplane Flight 
Manual (AFM) for Model 737-600, -700, and -700C series airplanes to 
prohibit operating the airplane at speeds in excess of 300 KIAS with 
speedbrakes extended. The FAA has determined that an airspeed of 300 
KIAS provides an acceptable safety margin compared to the 315-KIAS 
airspeed at which the severe vibration occurred.

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 this same type design, this 
airworthiness directive is issued to require revising the AFM to 
prohibit operating the airplane at speeds in excess of 300 KIAS with 
speedbrakes extended. This AD also provides for optional terminating 
action for the AFM revision.

Interim Action

    This AD is considered to be interim action. The specific details of 
the modification discussed previously are being developed, but are not 
yet available for dissemination to affected operators. Once the 
modification of the elevator tab assembly discussed previously is 
developed, approved, and available, the FAA may consider further 
rulemaking.
    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

[[Page 20627]]

effective immediately by individual notices issued on April 11, 2002, 
to all known U.S. owners and operators of Boeing Model 737-600, -700, 
and -700C series airplanes. 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 2002-NM-109-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, 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:

2002-08-52  Boeing: Amendment 39-12727. Docket 2002-NM-109-AD.

    Applicability: All Model 737-600, -700, -700C series airplanes, 
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 (c) 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 ensure that the flight crew is advised of the potential 
hazard associated with extending the speedbrakes at speeds in excess 
of 300 knots indicated airspeed (KIAS), accomplish the following:

Airplane Flight Manual (AFM) Revision

    (a) Within 24 clock hours after the effective date of this AD, 
revise the Limitations Section of the FAA-approved AFM to include 
the following information. This may be accomplished by inserting a 
copy of this AD into the Limitations Section of the AFM.
    ``Do not operate the airplane at speeds in excess of 300 KIAS 
with speedbrakes extended.
    Warning: Use of speedbrakes at speeds in excess of 320 KIAS 
could result in a severe vibration, which, in turn, could cause 
extreme damage to the horizontal stabilizer.''

Optional Terminating Action

    (b) Modification or retrofit of the elevator tab assembly in 
accordance with a method approved by the Manager, Seattle Aircraft 
Certification Office (ACO), FAA, constitutes terminating action for 
the AFM revision required by paragraph (a) of this AD. Following 
such modification or retrofit, that AFM revision may be removed from 
the AFM.

Alternative Methods of Compliance

    (c) 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 Operations or 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Seattle ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

Effective Date

    (d) This amendment becomes effective on May 1, 2002, to all 
persons except those persons to whom it was made immediately 
effective by emergency 2002-08-52, issued on April 11, 2002, which 
contained the requirements of this amendment.

    Issued in Renton, Washington, on April 19, 2002.
Lirio Liu-Nelson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-10249 Filed 4-25-02; 8:45 am]
BILLING CODE 4910-13-P