AD Amdt-39-11486

[Federal Register Volume 65, Number 2 (Tuesday, January 4, 2000)]
[Rules and Regulations]
[Pages 205-207]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 00-11]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-241-AD; Amendment 39-11486; AD 99-27-05]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 767-200, -300, and -300F 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 767-200, -300, and -300F series 
airplanes, that requires replacement of the hydraulic reducer fitting 
in the return port of the alternate brake selector valve with a new 
restrictor fitting. This amendment is prompted by a report indicating 
that a brake housing had fractured due to high loads associated with 
brake vibration during landing gear retraction, which allowed the 
torque rod to swing free. The actions specified by this AD are intended 
to prevent failure of the brake housing in the torque rod region, which 
could reduce the braking capability of the airplane and/or prevent the 
extension of a main landing gear by any method.

DATES: Effective February 8, 2000.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 8, 2000.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane

[[Page 206]]

Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information 
may be examined at the Federal Aviation Administration (FAA), Transport 
Airplane Directorate, Rules Docket, 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: David Herron, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (425) 227-2672; fax (425) 
227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 767-200, -
300, and -300F series airplanes was published in the Federal Register 
on August 4, 1998 (63 FR 41481). That action proposed to require 
replacement of the hydraulic reducer fitting in the return port of the 
alternate brake selector valve with a new restrictor fitting.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the comments received.

Support for the Proposal

    One commenter concurs with the requirements of the proposed AD. The 
Air Transport Association (ATA) of America states that one of its 
members does not currently operate any airplanes affected by the 
proposed rule, and another member has no objection to the proposed 
rule.

Request To Revise the Discussion Section

    One commenter states that it does not agree that the brake 
vibration is caused by excessive flow of hydraulic fluid into the 
alternate system metering valves during gear retract braking, as 
described in the Discussion section of the proposed AD. The commenter 
contends that the gear retract braking system, common to Model 757, 
747-400, and 777 series airplanes, and to Model 767 series airplanes 
equipped with steel brakes, has demonstrated trouble-free service 
experience in all of those airplane models without brake vibration. The 
brake vibration that has occurred during gear retract braking on Model 
767 series airplanes equipped with Boeing part number (P/N) S160T300-
series carbon brakes is attributed to the friction-material 
characteristics of the carbon brakes. Reducing the brake-pressure onset 
rate consistently reduces peak brake-torque amplitudes and brake 
vibration levels, when present.
    The new carbon brake, Boeing P/N S160T4000-210, for Model 767 
series airplanes, uses a new carbon heatsink that has demonstrated 
extremely stable dynamic characteristics during laboratory and flight 
tests. Therefore, replacement of the existing carbon brakes, P/N 
S160T300-series, with the new carbon brake will, in itself, alleviate 
the high loads associated with brake vibration, without replacing the 
hydraulic restrictor fitting. The commenter recommends revising the 
Discussion section to read ``Brake vibration during gear retract 
braking can be reduced on the existing carbon brakes by reducing the 
hydraulic flow to the brakes.''
    The FAA does not concur that the cause of the brake vibration on 
Model 767-200, -300, and -300F series airplanes is due to the brake 
material and not the gear retract braking system. In addition, it is 
not necessary to revise the Discussion section, as that section does 
not appear in the final rule.
    Because the brake system comprises a group of components that 
include the brake friction material and gear retract brakes, which are 
subsets of the brake system, the FAA considers each component to be a 
contributor to the unsafe condition. Additionally, Boeing Service 
Bulletin 767-32-0152, dated June 6, 1996, and Revisions 1 and 2 of that 
service bulletin, do not specify that the cause of the vibration is the 
brake material, but only that the vibration occurs in airplanes 
equipped with carbon brakes. In fact, the third paragraph of the 
Summary section of Revision 1 of the service bulletin states that 
``Installation of the restrictor fitting will reduce the flow into the 
alternate-system metering valves during gear retract braking. This will 
reduce peak torque levels and vibration of the landing gear during 
retract braking.''

Request To Change the Applicability of the Proposal

    The commenter states that since the brake vibration is associated 
only with P/N S160T300-series carbon brakes, the applicability of the 
AD should be revised to read ``Model 767-200, -300, and 300F series 
airplanes equipped with P/N S160T300-series carbon brakes; certified in 
any category.'' The FAA infers that the commenter considers that it is 
a combination of carbon brake material and the excessive onset of 
hydraulic pressure that results in the unsafe condition; and that 
brakes manufactured with a ceram-metallic composite, while benefiting 
from the change, do not exhibit the unsafe condition the FAA seeks to 
correct through the issuance of this AD.
    The FAA concurs that the brake vibration is associated only with 
airplanes equipped with Boeing P/N S160T300-series carbon brakes. The 
FAA also agrees with the manufacturer that including the specified part 
number in the applicability of the final rule correctly identifies 
those airplanes with the unsafe condition, and has revised the final 
rule accordingly. (The applicability of this AD continues to include 
the same airplanes ``1 through 607 inclusive;'' however, the term 
``line positions,'' which was used in the proposed AD, has been changed 
to ``line numbers'' in this AD.)

Request To Revise Certain Terminology

    One commenter states that, with reference to an alternative means 
(method) of compliance (AMOC), an ``equivalent'' level of safety rather 
than an ``acceptable'' level of safety should be considered. The 
commenter provides no justification for its request.
    The FAA does not concur that the level of safety should be 
specified as ``equivalent'' rather than ``acceptable.'' When 
considering any AMOC request, the Manager of the Seattle Aircraft 
Certification Office evaluates the request and determines whether the 
proposed AMOC request is acceptable (i.e., whether the proposed AMOC 
adequately addresses the unsafe condition). If so, the manager approves 
the request, even if it is not technically ``equivalent'' to the method 
of compliance required by the AD. No change to the final rule is 
necessary.

Conclusion

    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule with the change previously 
described. The FAA has determined that this change will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 373 Model 767-200, -300, and -300F series 
airplanes of the affected design in the worldwide fleet. The FAA 
estimates that 86 airplanes of U.S. registry will be affected by this 
AD, that it will take approximately 4 work hours per airplane to 
accomplish the required actions, and that the average labor rate

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is $60 per work hour. Required parts will cost approximately $104 per 
airplane. Based on these figures, the cost impact of the AD on U.S. 
operators is estimated to be $29,584, or $344 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the requirements of this AD 
action, and that no operator would accomplish those actions in the 
future if this AD were not adopted.

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:

99-27-05  Boeing: Amendment 39-11486. Docket 97-NM-241-AD.

    Applicability: Model 767-200, -300, and -300F series airplanes, 
line numbers 1 through 607 inclusive; equipped with part number 
S160T300-series carbon brakes; 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 (b) 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 failure of the brake housing in the torque rod 
region, which could reduce the braking capability of the airplane 
and/or prevent the extension of a main landing gear, accomplish the 
following:

Replacement

    (a) Within 360 days after the effective date of this AD, replace 
the hydraulic reducer fitting in the return port of the alternate 
brake selector valve with a new restrictor fitting, in accordance 
with Boeing Service Bulletin 767-32-0152, dated June 6, 1996; 
Revision 1, dated June 27, 1996; or Revision 2, dated July 10, 1997.

Alternative Methods of Compliance

    (b) 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 2: 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

    (c) 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

    (d) The replacement shall be done in accordance with Boeing 
Service Bulletin 767-32-0152, dated June 6, 1996; Boeing Service 
Bulletin 767-32-0152, Revision 1, dated June 27, 1996; or Boeing 
Service Bulletin 767-32-0152, Revision 2, dated July 10, 1997. 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.
    (e) This amendment becomes effective on February 8, 2000.

    Issued in Renton, Washington, on December 22, 1999.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-11 Filed 1-3-00; 8:45 am]
BILLING CODE 4910-13-U