[Federal Register Volume 61, Number 94 (Tuesday, May 14, 1996)]
[Proposed Rules]
[Pages 24250-24253]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-12021]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 96-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 supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 767 
series airplanes, that currently requires inspections to detect 
cracking and corrosion of the aft trunnion of the outer cylinder of the 
main landing gear (MLG) and various follow-on actions. That action also 
provides for the optional termination of the inspections by repairing 
the outer cylinder and installing new aft trunnion bushings. That AD 
was prompted by reports of failure of several MLG due to fractures of 
the aft trunnion outer cylinders. The actions specified by that AD are 
intended to prevent the collapse of the MLG due to stress corrosion 
cracking of the aft trunnion of the outer cylinder. This proposed 
action would require operators to implement the previously optional 
terminating action.

DATES: Comments must be received by June 24, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-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, Seattle Aircraft Certification Office, FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2783; fax (206) 227-1181.

[[Page 24251]]

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 96-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. 96-NM-25-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On February 22, 1996, the FAA issued AD 96-03-02 R1, amendment 39-
9526 (61 FR 7694, February 29, 1996). [AD 96-03-02 R1 was issued as a 
correction to AD 96-03-02, amendment 39-9497 (61 FR 3652, February 1, 
1996)]. That AD is applicable to certain Boeing Model 767 series 
airplanes, which requires various inspections to detect cracking and 
corrosion of the aft trunnion and various follow-on actions. That 
action was prompted by reports of failure of several main landing gears 
(MLG) due to fracture of the aft trunnion outer cylinder. The 
requirements of that AD are intended to prevent the collapse of the MLG 
due to stress corrosion cracking of the aft trunnion of the outer 
cylinder.
    That AD also provided for an optional action which, if 
accomplished, would constitute terminating action for the required 
inspections. In the preamble of that AD, the FAA indicated that this 
optional action, consisting of repair of the outer cylinder and 
replacement of the existing bushings with new bushings, was considered 
``interim action'' and that further rulemaking action to mandate the 
repair and replacement was being considered. The FAA also indicated 
that the proposed compliance time for the replacement was sufficiently 
long so that notice and public comment were practicable. As a follow-on 
action from that determination, the FAA is now proposing to mandate the 
previously optional repair and replacement.

Explanation of Relevant Service Information

    The FAA has previously reviewed and approved Boeing Alert Service 
Bulletin 767-32A0148, dated December 21, 1995, which describes 
procedures for repair of the outer cylinder and replacement of the 
existing bushings of the aft trunnion and crossbolt of the MLG with new 
bushings. Accomplishment of this repair and replacement eliminates the 
need for certain follow-on actions that are described in Boeing Service 
Bulletin 767-32A0151, dated November 30, 1995, which was referenced in 
AD 96-03-02 R1 as the appropriate source of service information.

FAA's Conclusions

    The FAA has determined that accomplishment of the repair and 
replacement specified in Boeing Alert Service Bulletin 767-32A0148 will 
positively address the unsafe condition identified as the failure of 
the MLG due to stress corrosion cracking of the aft trunnion of the 
outer cylinder.

Explanation of the 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 supersede AD 96-03-02 R1. It would continue to 
require various inspections to detect cracking and corrosion of the aft 
trunnion of the outer cylinder of the MLG, and require various follow-
on actions. The proposed AD also would require repair of the outer 
cylinder and replacement of the bushings in the aft trunnion and 
crossbolt of the MLG with new bushings. Accomplishment of the repair 
and replacement would constitute terminating action for the 
requirements of the AD.
    Accomplishment of the repair and replacement also would terminate 
the requirements of the following AD's:
    <bullet> AD 95-19-10, amendment 39-9372 (60 FR 47689, September 14, 
1995), and
    <bullet> AD 95-20-51, amendment 39-9398 (60 FR 53109, October 12, 
1995). [The comment period for AD 95-20-51 was extended by an AD action 
that was issued on November 28, 1995 (60 FR 62321, December 6, 1995.)]

Differences Between the Proposed AD and Relevant Service 
Information

    Operators should note that Boeing Alert Service Bulletin 767-
32A0148 refers to Component Maintenance Manual (CMM) 32-11-40, which, 
in turn, provides instructions for plugging the aft trunnion 
lubrication fitting with a rivet. This proposed AD, however, does not 
require plugging that fitting to terminate the requirements of this 
proposed AD, AD 95-19-10, or AD 95-20-51.

Cost Impact

    There are approximately 609 Boeing Model 767 series airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 204 
airplanes of U.S. registry would be affected by this proposed AD.
    The actions that are currently required by AD 96-03-02 R1, and 
retained in this AD, take approximately 34 work hours per airplane to 
accomplish, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact on U.S. operators of the actions 
currently required is estimated to be $416,160, or $2,040 per airplane.
    The new actions that are proposed in this AD action would take 
approximately 218 work hours per airplane to accomplish, at an average 
labor rate of $60 per work hour. Required parts would cost 
approximately $9,510 per airplane. Based on these figures, the cost 
impact on U.S. operators of the proposed requirements of this AD is 
estimated to be $4,608,360 or $22,590 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or 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

[[Page 24252]]

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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-9526 (61 FR 
7694, February 29, 1996), and by adding a new airworthiness directive 
(AD), to read as follows:

    Boeing: Docket 96-NM-25-AD. Supersedes AD 96-03-02 R1, Amendment 
39-9526.

    Applicability: Model 767 series airplanes having line numbers 
001 through 609, on which the terminating action described in 
paragraph (e) of this AD has not been accomplished; 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 (h) 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 the collapse of the main landing gear (MLG) due to 
stress corrosion cracking of the aft trunnion of the outer cylinder, 
accomplish the following:
    (a) Perform the inspections described in paragraph III, 
Accomplishment Instructions, of Boeing Alert Service Bulletin 767-
32A0151, dated November 30, 1995, to detect cracking and corrosion 
of the aft trunnion of the outer cylinder of the MLG at the time 
specified in paragraph (a)(1), (a)(2), or (a)(3) of this AD, as 
applicable. These inspections are to be accomplished in accordance 
with Figure 1 of that alert service bulletin. Repeat these 
inspections thereafter at the intervals specified in that alert 
service bulletin. To determine the category in which an airplane 
falls, the age of the outer cylinder of the MLG is to be calculated 
as of February 16, 1996, (the effective date of AD 96-03-02 R1, 
amendment 39-9526). For airplanes on which the age of the right MLG 
differs from the age of the left MLG, an operator may place the 
airplane into a category that is the higher (numerically) of the two 
categories to ease its administrative burden, and to simplify the 
recordkeeping requirements imposed by this AD. Once the category 
into which an airplane falls is determined, operators must obtain 
approval from the Manager, Seattle Aircraft Certification Office 
(ACO), FAA, Transport Airplane Directorate, to move that airplane 
into another category.

    Note 2: The broken (dash) lines used in Figure 1 of Boeing Alert 
Service Bulletin 767-32A0151, dated November 30, 1995, denote ``go 
to'' actions for findings of discrepancies detected during any of 
the inspections required by this AD.
    Note 3: Boeing Alert Service Bulletin 767-32A0151, dated 
November 30, 1995, refers to Boeing Alert Service Bulletin 767-
32A0148, dated December 21, 1995, for procedures to repair the outer 
cylinder and replace the bushings in the outer cylinder of the MLG 
with new bushings.

    (1) For airplanes identified as Category 3 in paragraph I.C. of 
Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995: 
Perform the initial inspections within 30 days after February 16, 
1996 (the effective date of AD 96-03-02 R1, amendment 39-9526).
    (2) For airplanes identified as Category 2 in paragraph I.C. of 
Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995: 
Perform the initial inspections within 90 days after February 16, 
1996, (the effective date of AD 96-03-02 R1, amendment 39-9526).
    (3) For airplanes identified as Category 1 in paragraph I.C. of 
Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995: 
Perform the initial inspections prior to the accumulation of 2\1/2\ 
years since the MLG outer cylinder was new or last overhauled, or 
within 150 days after February 16, 1996, (the effective date of AD 
96-03-02 R1, amendment 39-9526), whichever occurs later.
    (b) If no cracking or corrosion is detected, accomplish the 
follow-on actions described in the Boeing Alert Service Bulletin 
767-32A0151, November 30, 1995, at the time specified in the alert 
service bulletin. These follow-on actions are to be accomplished in 
accordance with that alert service bulletin.
    (c) If any cracking is detected, prior to further flight, 
replace the outer cylinder with a new or serviceable outer cylinder 
in accordance with Boeing Alert Service Bulletin 767-32A0151, dated 
November 30, 1995.
    (d) If any corrosion is detected, accomplish the follow-on 
actions at the time specified in the ``Corrosion Flowchart,'' in 
Figure 1 of Boeing Alert Service Bulletin 767-32A0151, dated 
November 30, 1995. The follow-on actions are to be accomplished in 
accordance with that alert service bulletin.
    (e) Repair the outer cylinder and replace the bushings in the 
aft trunnion and crossbolt of the MLG with new bushings, in 
accordance with Boeing Alert Service Bulletin 767-32A0148, dated 
December 21, 1995, at the time specified in either paragraph (e)(1) 
or (e)(2), as applicable. Accomplishment of this repair and 
replacement constitutes terminating action for this AD, and for the 
requirements of AD 95-19-10, amendment 39-9372; and AD 95-20-51, 
amendment 39-9398.

    Note 4: Boeing Alert Service Bulletin 767-32A0148 refers to 
Component Maintenance Manual (CMM) 32-11-40 for certain procedures. 
Operators should note that, although the CMM specifies plugging the 
aft trunnion lubrication fitting with a rivet, this AD does not 
require this action to be accomplished in order to terminate the 
requirements of this AD, AD 95-19-10, or AD 95-20-51. Plugging the 
aft trunnion lubrication fitting with a rivet is the operator's 
prerogative.

    (1) For airplanes identified as Category 3 in paragraph I.C. of 
Boeing Alert Service Bulletin 767-32A0151, dated November 30, 1995: 
Accomplish the repair and replacement prior to the accumulation of 5 
and years since the MLG outer cylinders were new or last overhauled, 
or within 18 months after the effective date of this AD, whichever 
occurs later.
    (2) For airplanes identified as either Category 1 or Category 2 
in paragraph I.C. of Boeing Alert Service Bulletin 767-32A0151, 
dated November 30, 1995, accomplish the repair and replacement at 
the time specified in either paragraph (e)(2)(i) or (e)(2)(ii) of 
this AD:
    (i) Prior to the accumulation of 5 and 1/2 years since the MLG 
outer cylinders were new or last overhauled, or within 18 months 
after the effective date of this AD, whichever occurs later. Or,
    (ii) Prior to the accumulation of 7 years since the MLG outer 
cylinders were new or last overhauled, provided that accomplishment 
of visual and non-destructive testing (NDT) inspections at the times 
specified in Figure 1 of the Accomplishment Instructions of Boeing 
Alert Service Bulletin 767-32A0151, dated November 30, 1995, are 
repeated until the repair and replacement are accomplished.
    (g) Accomplishment of the inspection requirements of this AD [in 
accordance with Boeing Alert Service Bulletin 767-32A0151,

[[Page 24253]]

dated November 30, 1995] is considered acceptable for compliance 
with AD 95-19-10, amendment 39-9372; and AD 95-20-51, amendment 39-
9398.
    (h)(1) 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 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.

    (2) Alternative methods of compliance, approved in accordance 
with AD 96-03-02, amendment 39-9497; or AD 93-03-02 R1, amendment 
39-9526; are approved as alternative methods of compliance with this 
AD.
    (i) 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.

    Issued in Renton, Washington, on May 8, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-12021 Filed 5-13-96; 8:45 am]
BILLING CODE 4910-13-U