[Federal Register Volume 65, Number 251 (Friday, December 29, 2000)]
[Proposed Rules]
[Pages 82959-82961]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-33343]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-147-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 777-200 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 777-200 
series airplanes. This proposal would require replacement of certain 
existing bushings of the aft trunnion of the outer cylinder of the main 
landing gear (MLG) with new bushings, and replacement of grease in an 
undercut on the aft trunnion, if necessary. This action is necessary to 
prevent stress corrosion cracking and consequent fracture of the aft 
trunnion of the outer cylinder of the MLG, which could result in 
collapse of the MLG. This action is intended to address the identified 
unsafe condition.

DATES: Comments must be received by February 12, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-147-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: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-147-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 the proposed rule 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.

FOR FURTHER INFORMATION CONTACT: Stan Wood, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
227-2772; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as

[[Page 82960]]

they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this action may be changed in 
light of the comments received.
    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 proposed 
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 proposed 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 summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-147-AD.'' The postcard will be date stamped 
and returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules 
Docket No. 2000-NM-147-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received several reports of cracking of the aft 
trunnion of the outer cylinder of the main landing gear (MLG) on 
certain Boeing Model 767 series airplanes. The aft trunnion is attached 
to the MLG beam by the aft trunnion pin. Bushings are installed in the 
aft trunnion at the place where a cross bolt retains the aft trunnion 
pin. Moisture can enter the aft trunnion in the area of these bushings. 
There is also an undercut on the aft trunnion in the area of the cross 
bolt, which is filled with grease during assembly of the MLG. This 
grease in the undercut can dry out over time, which may allow moisture 
to enter the aft trunnion and undercut areas. The accumulation of 
moisture can result in the formation of corrosion pits on the aft 
trunnion, which can lead to stress corrosion cracking and consequent 
fracture of the aft trunnion. This condition, if not corrected, could 
result in collapse of the MLG.
    The design of the aft trunnion of the outer cylinder of the MLG on 
certain Boeing Model 777-200 series airplanes is similar to that on the 
affected Model 767 series airplanes. Therefore, those Model 777-200 
series airplanes are subject to the same unsafe condition found on the 
Model 767 series airplanes.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
777-32A0025, dated April 6, 2000, which describes procedures for 
replacement of certain existing bushings of the aft trunnion of the 
outer cylinder of the MLG with new bushings installed with corrosion-
inhibiting compound. The procedures include removing the existing 
bushings, performing a detailed visual inspection of the aft trunnion 
area for corrosion or other damage, removing corrosion, if necessary, 
and installing new bushings with corrosion-inhibiting compound. For 
airplanes listed under Group 1 in the service bulletin, the service 
bulletin also includes instructions for replacing grease in the 
undercut of the aft trunnion with corrosion-inhibiting compound. These 
actions will prevent moisture from entering the aft trunnion and 
undercut areas, where such moisture can lead to the formation of 
corrosion pits. (Airplanes listed under Group 2 do not have an undercut 
area.) Accomplishment of the actions specified in the service bulletin 
is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require accomplishment of the actions specified in 
the service bulletin described previously, except as discussed below.

Differences Between Service Bulletin and This AD

    Operators should note that, although the effectivity listing of the 
service bulletin includes airplanes having line numbers (L/N) 2 through 
29 inclusive; except L/N's 10, 14, and 18; this proposed AD would apply 
to airplanes having L/N's 1 through 29 inclusive, except L/N's 10, 14, 
and 18. The FAA has determined that the subject area on the airplane 
with L/N 1 is identical to the subject areas on the Model 777-200 
series airplanes listed in the service bulletin; therefore, the 
airplane with L/N 1 is also subject to the identified unsafe condition. 
Also, Note 3 has been included in this proposed AD to clarify that L/N 
1 has the configuration of a Group 1 airplane.
    Operators also should note that, although the service bulletin 
specifies that the manufacturer may be contacted for instructions on 
repair of certain 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.

Cost Impact

    There are approximately 26 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 12 airplanes of U.S. registry 
would be affected by this proposed AD, that it would take approximately 
36 work hours per airplane to accomplish the proposed actions, and that 
the average labor rate is $60 per work hour. Required parts would cost 
approximately $13,228 per airplane. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be 
$184,656, or $15,388 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed requirements of 
this AD action, and that no operator would accomplish those actions in 
the future if this proposed AD were not adopted. The cost impact 
figures discussed in AD rulemaking actions represent only the time 
necessary to perform the specific actions actually required by the AD. 
These figures typically do not include incidental costs, such as the 
time required to gain access and close up, planning time, or time 
necessitated by other administrative actions.

Regulatory Impact

    The regulations proposed herein would 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,

[[Page 82961]]

it is determined that this proposal would not have federalism 
implications under Executive Order 13132.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 
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:

Boeing: Docket 2000-NM-147-AD.

    Applicability: Model 777-200 series airplanes; line numbers (L/
N) 1 through 29 inclusive, except L/N's 10, 14, and 18; certificated 
in any category; except those on which the outer cylinder of the 
main landing gear (MLG) has been replaced in accordance with Boeing 
Service Bulletin 777-32-0003, dated October 9, 1997.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 prevent stress corrosion cracking and consequent fracture of 
the aft trunnion of the outer cylinder of the MLG, which could 
result in collapse of the MLG, accomplish the following:

Replacement of Bushings

    (a) Within 5 years and 300 days since date of manufacture of the 
airplane, or within 1 year after the effective date of this AD, 
whichever occurs later, replace bushings in the aft trunnion of the 
outer cylinder with new bushings by doing paragraphs (a)(1), (a)(2), 
(a)(3), and (a)(4) of this AD; as applicable; in accordance with 
Boeing Alert Service Bulletin 777-32A0025, dated April 6, 2000.
    (1) Remove bushings in the aft trunnion of the outer cylinder of 
the MLG.
    (2) Perform a one-time detailed visual inspection of the aft 
trunnion area for corrosion or other damage.
    (3) For airplanes listed in Group 1 of the service bulletin and 
the airplane having L/N 1: Replace grease in the undercut of the aft 
trunnion with corrosion-inhibiting compound.
    (4) Install new bushings with corrosion-inhibiting compound.

    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.''


    Note 3: For the purposes of this AD, the airplane having L/N 1 
is considered to have the configuration of a Group 1 airplane.

Corrective Action

    (b) If any corrosion or other damage is found during the 
inspection required by paragraph (a)(2) of this AD: Prior to further 
flight, repair in accordance with Boeing Alert Service Bulletin 777-
32A0025, dated April 6, 2000; except, where the service bulletin 
specifies to contact Boeing for instructions, prior to further 
flight, repair in accordance with a method approved by the Manager, 
Seattle Aircraft Certification Office (ACO), FAA; or in accordance 
with data meeting the type certification basis of the airplane 
approved by a Boeing Company Designated Engineering Representative 
(DER) 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

    (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, 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 4: 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

    (d) Special flight permits may be issued in accordance with 
Secs. 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.

    Issued in Renton, Washington, on December 22, 2000.
John J. Hickey,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-33343 Filed 12-28-00; 8:45 am]
BILLING CODE 4910-13-P