[Federal Register Volume 64, Number 143 (Tuesday, July 27, 1999)]
[Rules and Regulations]
[Pages 40514-40516]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-18364]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 99-NM-155-AD; Amendment 39-11229; AD 99-15-09]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600 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), 
applicable to certain Boeing Model 737-600 series airplanes. This 
action requires revising the Airplane Flight Manual (AFM) to prohibit 
operation of the airplane under certain conditions; repetitive 
inspections of the tab mast fittings of the elevator tab assemblies to 
detect cracking; an elevator tab freeplay check; and corrective 
actions, if necessary. This AD also requires installing an additional 
fastener on the elevator tab mast fitting, which terminates the AFM 
revision and extends certain repetitive inspections. This AD also 
requires replacement of the elevator tab mast fitting with a new, 
improved fitting, which constitutes terminating action for the 
requirements of this AD. This amendment is prompted by a report of a 
severe vibration incident on a Boeing Model 737-800 series airplane; 
inspection revealed fracturing of the elevator tab mast fitting and 
excessive freeplay in the elevator tab. The actions specified in this 
AD are intended to prevent loss of controllability of the airplane due 
to excessive freeplay in the elevator tab or a free tab.

DATES: Effective August 11, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of August 11, 1999.
    Comments for inclusion in the Rules Docket must be received on or 
before September 27, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 99-NM-155-AD, 1601 Lind Avenue, SW., 
Renton, Washington 98055-4056.
    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: Gregory L. Schneider, Aerospace 
Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (425) 227-2028; fax (425) 
227-1181.

SUPPLEMENTARY INFORMATION: On June 2, 1999, the FAA received a report 
of a severe vibration incident on a Boeing Model 737-800 series 
airplane, which had accumulated 3,517 total flight hours and 1,284 
total flight cycles. The airplane was involved in a high-speed descent 
with speed brakes extended while operating at an airspeed of 320 knots. 
During the descent, severe vibration occurred at 250 knots. At 230 
knots, the speed brakes were retracted and the vibration stopped. The 
landing was uneventful.
    Inspection of the airplane revealed that the upper flange of the 
right elevator tab mast fitting, to which the elevator tab push rods 
are attached, was found fractured. The lower flange of the fitting was 
not damaged. In addition, excessive freeplay in the elevator tab also 
was observed and measured during the inspection.
    Further analysis confirmed that the damage to the fitting was 
aggravated by speed-brake-induced airframe vibration. Such vibration 
could lead to damage of the elevator tab mast fitting, excessive 
freeplay in the tab, and consequent separation of the tab mast fitting 
from the tab. Excessive freeplay in the tab could result in severe 
airframe vibration and consequent damage to the tab, elevator, and 
horizontal stabilizer. Separation of the elevator tab mast fitting will 
result in a free tab. These conditions, if not corrected, could result 
in loss of controllability of the airplane.
    In light of this information, on June 10, 1999, the FAA issued 
telegraphic AD T99-13-51, which is applicable to certain Boeing Model 
737-700 and -800 series airplanes. In addition, the FAA has received 
information indicating that Boeing Model 737-600 series airplanes also 
are subject to the unsafe condition identified in telegraphic AD T99-
13-51. Therefore, the FAA has determined that rulemaking action is 
necessary to address that unsafe condition on Model 737-600 series 
airplanes.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
737-55A1068, Revision 1, dated June 11, 1999, which describes 
procedures for repetitive high frequency eddy current (HFEC) and 
detailed visual inspections of the tab mast fittings of the left and 
right elevator tab assemblies to detect cracking, and a one-time 
elevator tab freeplay check to detect excessive freeplay of the 
elevator tabs; and corrective actions, if necessary. The alert service 
bulletin also describes procedures for installing an additional high-
strength fastener on the elevator tab mast fitting (time-limited 
modification).
    The FAA also has reviewed and approved Boeing Service Bulletin 737-
55-1063, dated July 1, 1999, which describes procedures for replacing a 
cracked elevator tab mast fitting with a new, improved fitting. Such 
replacement eliminates the need for repetitive inspections of the 
elevator tab mast fittings.

Explanation of 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 prevent loss of controllability of the airplane due to 
excessive freeplay in the elevator tab or a free tab. This AD requires 
revising the Limitations Section of the FAA-approved Airplane Flight 
Manual (AFM) to prohibit operation of the airplane at certain airspeeds 
with the speed brakes extended, and at certain altitudes.
    This AD also requires repetitive HFEC and detailed visual 
inspections of the tab mast fittings of the left and right elevator tab 
assemblies to detect cracking, and a one-time elevator tab freeplay 
check to detect excessive freeplay of the elevator tab; and corrective 
actions, if necessary.
    Additionally, this AD requires installing an additional high-
strength fastener on the elevator tab mast fitting (time-limited 
modification). Such installation terminates the AFM revision and allows 
extension of the repetitive interval for accomplishment of the HFEC and 
detailed visual inspections.
    This AD also requires replacement of the elevator tab mast fittings 
with new, improved fittings, which constitutes

[[Page 40515]]

terminating action for the requirements of this AD.
    Certain inspections and checks are required to be accomplished in 
accordance with Boeing Alert Service Bulletin 737-55A1068, Revision 1. 
Replacement actions are required to be accomplished in accordance with 
Boeing Service Bulletin 737-55-1063, dated July 1, 1999.
    It should be noted that, except as otherwise provided for in the 
AFM emergency procedures, this AD prohibits the deployment of the 
spoilers at speeds in excess of 310 knots indicated airspeed (IAS) with 
speed brakes extended. This AD also prohibits operation of the airplane 
above FL 390. The FAA recognizes that under emergency circumstances, as 
specified in the AFM, it might become necessary to deploy spoilers in 
excess of 310 knots IAS. In that event, this AD requires accomplishment 
of the HFEC and detailed visual inspections of the elevator tab mast 
fittings and of the check of the tabs for freeplay, prior to further 
flight after landing.

Cost Impact

    None of the Model 737-600 series airplanes affected by this action 
are on the U.S. Register. All airplanes included in the applicability 
of this rule currently are operated by non-U.S. operators under foreign 
registry; therefore, they are not directly affected by this AD action. 
However, the FAA considers that this rule is necessary to ensure that 
the unsafe condition is addressed in the event that any of these 
subject airplanes are imported and placed on the U.S. Register in the 
future.
    Should an affected airplane be imported and placed on the U.S. 
Register in the future:
    It would require approximately 2 work hours to accomplish the 
inspection and check, at an average labor rate of $60 per work hour. 
Based on this figure, the cost impact of the inspection and check 
required by this AD would be $120 per airplane.
    It would require approximately 3 work hours to accomplish the time-
limited modification, at an average labor rate of $60 per work hour. 
Based on this figure, the cost impact of the time-limited modification 
required by this AD would be $180 per airplane.
    It would require approximately 8 work hours to accomplish the 
replacement action, at an average labor rate of $60 per work hour. 
Required parts would cost approximately $5,149 per airplane. Based on 
these figures, the cost impact of the replacement required by this AD 
would be $5,629 per airplane.

Determination of Rule's Effective Date

    Since this AD action does not affect any airplane that is currently 
on the U.S. register, it has no adverse economic impact and imposes no 
additional burden on any person. Therefore, prior notice and public 
procedures hereon are unnecessary and the amendment may be made 
effective in less than 30 days after publication in the Federal 
Register.

Comments Invited

    Although this action is in the form of a final rule and was not 
preceded by notice and 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 99-NM-155-AD.'' The postcard will be date stamped and 
returned to the commenter.

Regulatory Impact

    The regulations adopted herein will not have substantial direct 
effects 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, in accordance with Executive Order 12612, it is 
determined that this final rule does not have sufficient federalism 
implications to warrant the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under 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. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it 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:

99-15-09  Boeing: Amendment 39-11229. Docket 99-NM-155-AD.

    Applicability: Model 737-600 series airplanes having line 
numbers 1 through 190, 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 (g) 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 prevent loss of controllability of the airplane due to 
excessive freeplay in the elevator tab or a free tab, accomplish the 
following:

[[Page 40516]]

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 
AFM.
    Except as otherwise provided for in the AFM emergency 
procedures, do not operate the airplane at speeds in excess of 310 
knots indicated airspeed (IAS) with speed brakes extended. Do not 
operate the airplane above FL 390.
    (b) In the event of deployment of the speed brakes at speeds in 
excess of 310 knots indicated airspeed (IAS), prior to further 
flight after landing, accomplish the requirements of paragraph (c) 
of this AD.

Inspections and Check

    Note 2: Accomplishment of the inspections and check required by 
this AD, prior to the effective date of this AD, in accordance with 
Boeing Alert Service Bulletin 737-55A1068, dated June 9, 1999, is 
considered acceptable for compliance with the repetitive inspections 
and checks required by paragraphs (c) and (d) of this AD.

    (c) Within 10 days after the effective date of this AD, perform 
a high frequency eddy current (HFEC) inspection, and a detailed 
visual inspection of the elevator tab mast fittings of the left and 
right elevator tab assemblies to detect cracking, and a one-time 
elevator tab freeplay check to detect freeplay of the elevator tabs, 
in accordance with Boeing Alert Service Bulletin 737-55A1068, 
Revision 1, dated June 11, 1999.

    Note 3: For the purposes of this AD, a detailed 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.''

    (1) If no cracking is found in any elevator tab mast fitting, 
repeat the HFEC and detailed visual inspections thereafter at 
intervals not to exceed 15 days, until accomplishment of the actions 
required by paragraph (d) of this AD.
    (2) If any cracking is found in any elevator tab mast fitting, 
prior to further flight, accomplish the requirements of paragraph 
(e) of this AD.
    (3) If any freeplay is found in any elevator tab, which is 
outside the limits specified in the alert service bulletin, prior to 
further flight, perform corrective actions in accordance with the 
alert service bulletin.

    Note 4: Boeing Alert Service Bulletin 737-55A1068, Revision 1, 
dated June 11, 1999, references Boeing Model 737-600/-700/-800 
Maintenance Manual (AMM), Subjects 27-09-91, 27-31-00, and 51-21-99; 
737 Nondestructive Test (NDT) Manual D6-37239, Part 6, Subject 55-
00-00; 737 Structural Repair Manual (SRM) Subject 51-20-81; and 
Operations Manual Service Bulletin D6-27370-TBC (``Elevator Tab 
Operational Limitations''), dated June 10, 1999; as additional 
sources of service information to accomplish certain requirements of 
this AD.

Time-Limited Modification

    (d) Within 90 days after the effective date of this AD, install 
an additional high-strength fastener on the elevator tab mast 
fitting in accordance with Boeing Alert Service Bulletin 737-
55A1068, Revision 1, dated June 11, 1999. Accomplishment of this 
modification constitutes terminating action for the requirements of 
paragraph (b) of this AD. Following accomplishment of the 
installation, the AFM revision required by paragraph (a) of this AD 
may be removed from the AFM. Following accomplishment of the 
installation, repeat the HFEC and detailed visual inspections 
required by paragraph (c) of this AD thereafter at intervals not to 
exceed 90 days until accomplishment of paragraph (e) of this AD.

Terminating Action

    (e) Within 4,000 flight cycles or 18 months after the effective 
date of this AD, whichever occurs earlier, replace the elevator tab 
mast fittings with new, improved tab mast fittings, in accordance 
with Boeing Service Bulletin 737-55-1063, dated July 1, 1999. 
Accomplishment of this replacement action constitutes terminating 
action for the requirements of this AD.

Spares

    (f) As of the effective date of this AD, no elevator tab mast 
fitting, part number (P/N) 183A8400-1 or 183A8400-2, shall be 
installed on any airplane.

Alternative Methods of Compliance

    (g) 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 Aircraft Certification 
Office (ACO), FAA, Transport Airplane Directorate. 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 5: 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

    (h) 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

    (i) Except as provided by paragraphs (a) and (b) of this AD, the 
actions shall be done in accordance with Boeing Alert Service 
Bulletin 737-55A1068, Revision 1, dated June 11, 1999, and Boeing 
Service Bulletin 737-55-1063, dated July 1, 1999. 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.
    (j) This amendment becomes effective on August 11, 1999.

    Issued in Renton, Washington, on July 13, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-18364 Filed 7-26-99; 8:45 am]
BILLING CODE 4910-13-P