[Federal Register Volume 61, Number 22 (Thursday, February 1, 1996)]
[Rules and Regulations]
[Pages 3552-3555]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-1568]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-NM-02-AD; Amendment 39-9497; AD 96-03-02]


Airworthiness Directives; Boeing Model 767 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to certain Boeing Model 767 series airplanes. This action 
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. This action provides for termination of the 
inspections by repairing the outer cylinder and installing new aft 
trunnion bushings. This amendment is prompted by a report of the 
collapse of the right MLG due to fracture of the aft trunnion outer 
cylinder. The actions specified in this AD are intended to prevent the 
collapse of the MLG due to stress corrosion cracking of the aft 
trunnion of the outer cylinder.

DATES: Effective February 16, 1996.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of February 16, 1996.
    Comments for inclusion in the Rules Docket must be received on or 
before April 1, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 96-NM-02-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056.
    The service information referenced in this AD 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; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: James G. Rehrl, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2783; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA recently received a report of the 
collapse of the right main landing gear (MLG) of a Boeing Model 767-
300ER airplane while the airplane was taxiing in a low speed right-hand 
turn. Investigation revealed that the cause of the collapse of the MLG 
was attributed to the fracture of the aft trunnion outer cylinder due 
to stress corrosion cracking. The cracking initiated at the crossbolt 
hole, which is approximately 

[[Page 3553]]
five inches from the aft trunnion bushing flange. This condition, if 
not corrected, could result in the collapse of the MLG due to ductile 
fracture of the aft trunnion of the outer cylinder.
    The FAA has reviewed and approved Boeing Alert Service Bulletin 
767-32A0151, dated November 30, 1995. The alert service bulletin places 
affected airplanes into three categories:
     Category 1 airplanes have outer cylinders of the MLG that 
have accumulated 2\1/2\ years or less since the cylinder was new or 
overhauled.
     Category 2 airplanes have outer cylinders of the MLG that 
have accumulated between 2\1/2\ years and 4 years since new or 
overhauled.
     Category 3 airplanes have outer cylinders of the MLG that 
have accumulated 4 years or more since new or overhauled.
    This categorization reflects the time-related phenomenon of 
corrosion; i.e., the risk of developing corrosion (or stress corrosion 
cracking) increases with the length of time that an outer cylinder has 
been in service. Therefore, Category 3 comprises airplanes that are 
generally at the greatest risk of experiencing stress corrosion 
cracking .
    The alert service bulletin describes the procedures necessary for 
performing various visual, eddy current, and ultrasonic inspections; 
and when appropriate, for performing chemical spot testing of the aft 
trunnion of the outer cylinder of the MLG (hereinafter referred to as 
the ``aft trunnion''). It also includes the following actions for all 
three categories of airplanes:
    1. replacement of the outer cylinder, if cracking is found;
    2. replacement of the aft trunnion bushing and crossbolt bushings; 
or repeat the visual, eddy current, and ultrasonic inspections of the 
immediate area in which corrosion is found in the aft trunnion;
    3. application of plating and finish to the outer cylinder, if the 
finish is found to be damaged or missing;
    4. functional testing of the lock link actuator;
    5. repetitive visual inspections, or termination of the inspections 
by repairing the outer cylinder and installing flangeless aft trunnion 
bushings and new crossbolt bushings;
    6. repetitive 360-degree close visual inspection of the aft 
trunnion, including the crossbolt area;
    7. application of corrosion inhibiting compound on the aft 
trunnion; and
    8. eventual repair of the outer cylinder and replacement of the 
existing aft trunnion and crossbolt bushings with new bushings, which 
terminates the inspections specified in the alert service bulletin.
    The alert service bulletin refers to 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. The FAA 
has also reviewed and approved this alert service bulletin.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Model 767 series airplanes of the same type 
design, this AD is being issued to prevent the collapse of the MLG due 
to stress corrosion cracking of the aft trunnion of the outer cylinder. 
This AD requires various inspections to detect cracking and corrosion 
of the aft trunnion and various follow-on actions. The actions are 
required to be accomplished in accordance with Boeing Alert Service 
Bulletin 767-32A0151, described previously.
    The compliance times for accomplishing these inspections are 
dependent upon the age of the outer cylinders of the MLG. Category 3 
airplanes, which have the oldest cylinders, are to be inspected within 
30 days (the alert service bulletin recommends inspecting these 
airplanes within 60 days). Category 2 airplanes are to be inspected 
within 90 days (the alert service bulletin recommends inspecting these 
airplanes within 120 days). Category 1 airplanes, which have the 
youngest cylinders, are to be inspected within 150 days (the alert 
service bulletin recommends inspecting these airplanes within 180 
days).
    In developing an appropriate compliance time for this action, the 
FAA considered not only the degree of urgency associated with 
addressing the subject unsafe condition, but the manufacturer's 
recommendation as to an appropriate compliance time, the availability 
of required parts, and the practical aspects of performing the 
inspections. The FAA points out that the varying compliance times allow 
the manufacturer sufficient time to produce all the eddy current 
probes, ultrasonic transducers, and non-destructive inspection (NDI) 
reference standards that operators need to accomplish the inspections. 
Further, the FAA took into account the compliance times recommended by 
the manufacturer, as well as the number of days required for the 
rulemaking process; in consideration of these factors, the FAA finds 
that the compliance times required by this AD will fall approximately 
at the same time as those recommended by the manufacturer.
    Operators should note that, although Boeing Alert Service Bulletin 
767-32A0151 specifies eventual repair of the outer cylinder and 
replacement of the existing bushings with new bushings, this AD does 
not require such replacement. The FAA is considering further rulemaking 
action to require eventual replacement of the bushings. However, the 
planned compliance time for the replacement is sufficiently long so 
that prior notice and time for public comment will be practicable.
    This AD does provide operators with the option of terminating the 
requirement for the repetitive inspections by replacing the bushings 
with new bushings in accordance with Boeing Alert Service Bulletin 767-
32A0148, dated December 21, 1995. Accomplishment of this bushing 
replacement also terminates 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.)]
    Operators should also 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 AD, however, does not require 
plugging this lube fitting to terminate the requirements of this AD, AD 
95-19-10, or AD 95-20-51.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 

[[Page 3554]]
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 that 
summarizes each FAA-public contact concerned with the substance of this 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 96-NM-02-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

96-03-02  Boeing: Amendment 39-9497. Docket 96-NM-02-AD.

    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 use the authority 
provided in paragraph (g) of this AD to request approval from the 
FAA. This approval may address either no action, if the current 
configuration eliminates the unsafe condition; or different actions 
necessary to address the unsafe condition described in this AD. Such 
a request should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    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 Part 3 of the 
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 the effective date of this AD. 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 the effective 
date of this AD.
    (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 the effective 
date of this AD.
    (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 overhauled, or within 
150 days after the effective date of this AD, 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 of the outer cylinder and replacement of 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, constitutes terminating action for the inspection 
requirements of this AD, and for the requirements of AD 95-19-10, 
amendment 39-9372, and AD 95-20-51, amendment 39-9398. Boeing Alert 
Service Bulletin 767-32A0148, dated December 21, 1995, refers to 
Component Maintenance Manual (CMM) 32-11-40. Operators should note 
that, although the CMM specifies plugging the aft trunnion 
lubrication fitting with a rivet, this AD does not require plugging 
the lube fitting to terminate the requirement of this AD, AD 95-19-
10, or AD 95-20-51.
    (f) Accomplishment of the requirements of this AD is considered 
acceptable for compliance with AD 95-19-10, amendment 

[[Page 3555]]
39-9372, and AD 95-20-51, amendment 39-9398.
    (g) 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 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (h) 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.
    (i) The inspections and follow-on actions shall be done in 
accordance with Boeing Alert Service Bulletin 767-32A0151, dated 
November 30, 1995. Certain replacements and repairs shall be done in 
accordance with Boeing Alert Service Bulletin 767-32A0148, dated 
December 21, 1995. 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.
    (j) This amendment becomes effective on February 16, 1996.

    Issued in Renton, Washington, on January 22, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-1568 Filed 1-31-96; 8:45 am]
BILLING CODE 4910-13-U