[Federal Register Volume 62, Number 62 (Tuesday, April 1, 1997)]
[Proposed Rules]
[Pages 15435-15437]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-8128]


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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 97-NM-25-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 767 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 767 series 
airplanes. This proposal would require a one-time inspection of the 
main landing gear (MLG) retaining bolt to ensure that it is installed 
correctly, and adjustments or repairs, if necessary. This proposal is 
prompted by a report indicating that a disconnected retaining bolt was 
found in the MLG forward trunnion joint of a Model 767 series airplane. 
The actions specified by the proposed AD are intended to prevent aft-
acting trunnion loads from being transferred to the MLG beam, and 
consequent fracture and collapse of the MLG; this condition could 
result in the loss of control of the airplane on the ground.

DATES: Comments must be received by May 9, 1997.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 97-NM-25-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.
    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: James G. Rehrl, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-2783; 
fax (206) 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 
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 notice may be changed in 
light of the comments received.
    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 notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 97-NM-25-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-103, Attention: Rules 
Docket No. 97-NM-25-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

[[Page 15436]]

Discussion

    Boeing notified the FAA that an unsafe condition may exist on 
certain Model 767 series airplanes. Boeing advises that the FAA 
received a report indicating that a disconnected retaining bolt was 
found in the forward trunnion joint of the main landing gear (MLG) 
during the first ``2C'' check of a Model 767-300 series airplane. The 
inspection revealed these findings:
    1. The retaining bolt was found jammed between the H-fitting and 
wing rear spar.
    2. The aft trunnion joint and MLG beam did not show any damage.
    3. The tabs of the retaining ring were not engaged with the mating 
slots in the bearing housing before the retaining bolt was tightened 
into the outer cylinder of the MLG. This allowed the retaining bolt to 
turn and back out of the forward trunnion threads.
    The retaining bolt provides axial retention of the spherical 
bearing in the forward trunnion joint, which is the design load path 
for transferring aft-acting landing gear trunnion loads into the wing 
rear spar H-fitting. If the retaining bolt is disconnected, the aft-
acting trunnion loads are not transferred by the design load path to 
the H-fitting of the wing rear spar, but are instead transferred to the 
MLG beam at the aft trunnion joint. This condition, if not corrected, 
could cause the MLG to fracture and collapse, and could result in the 
loss of control of the airplane on the ground.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
767-32A0157, dated October 10, 1996, which describes procedures for a 
one-time inspection of the MLG retaining bolt to ensure that it is 
installed correctly, and adjustments or repairs, if necessary. 
Accomplishment of these procedures will preclude the aft-acting landing 
gear trunnion loads from being transferred to the MLG beam.

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 a one-time inspection of the MLG retaining 
bolt to ensure that it is installed correctly, and adjustments or 
repairs, if necessary. These actions would be required to be 
accomplished in accordance with the alert service bulletin described 
previously.

Cost Impact

    There are approximately 598 Boeing Model 767 series airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 151 
airplanes of U.S. registry would be affected by this proposed AD, that 
it would take approximately 5 work hours per airplane to accomplish the 
proposed actions, and that the average labor rate is $60 per work hour. 
Based on these figures, the cost impact of the proposed AD on U.S. 
operators is estimated to be $45,300, or $300 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 AD were not adopted.

Regulatory Impact

    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    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 97-NM-25-AD.

    Applicability: Model 767 series airplanes, line positions 1 
through 600 inclusive, except line positions 579 and 586; 
certificated in any category.

    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 (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 aft-acting landing gear trunnion loads from being 
transferred to the main landing gear (MLG) beam, and consequent 
fracture and collapse of the MLG and loss of control of the airplane 
on the ground, accomplish the following:
    (a) Within 500 flight hours or 300 flight cycles after the 
effective date of this AD, whichever occurs later, perform a one-
time inspection of the MLG retaining bolt to ensure that it is 
installed correctly, in accordance with Boeing Alert Service 
Bulletin 767-32A0157, dated October 10, 1996. If the retaining bolt 
is incorrectly installed, prior to further flight, make adjustments 
or repairs in accordance with the alert service bulletin.
    (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.

    (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.


[[Page 15437]]


    Issued in Renton, Washington, on March 25, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-8128 Filed 3-31-97; 8:45 am]
BILLING CODE 4910-13-U