[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:
AD 95-19-10, amendment 39-9372 (60 FR 47689, September 14,
1995), and
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,
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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