[Federal Register Volume 60, Number 178 (Thursday, September 14, 1995)]
[Rules and Regulations]
[Pages 47689-47691]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-22715]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-149-AD; Amendment 39-9372; AD 95-19-10]


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 all Boeing Model 767 series airplanes. This action 
requires operators to perform visual inspections of the outer cylinder 
aft trunnion on the main landing gear to determine if the fillet seal 
is cracked or missing. This action also requires operators to inspect 
for evidence of corrosion in this location. Finally, this action 
prescribes the procedures that operators must follow if corrosion is 
found. This amendment is prompted by several reports of fractures of 
the outer cylinder aft trunnion due to stress corrosion cracking. The 
actions specified in this AD are intended to ensure that corrosion is 
not present in this location, thereby preventing future failures due to 
stress corrosion cracking.

DATES: Effective September 29, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 29, 1995.
    Comments for inclusion in the Rules Docket must be received on or 
before November 13, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-149-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, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-2783; 
fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: The FAA has received reports of fractures of 
the outer cylinder of the aft trunnion of the main landing gear (MLG) 
on three Boeing Model 767 series airplanes. One of the three airplanes 
was six years old and had accumulated 28,887 total flight hours; 
another was six years old and had accumulated 25,841 total flight 
hours; and the third was eight years old and had accumulated 27,177 
total flight hours. All of these airplanes were equipped with the 
original MLG, none of which had been overhauled at the time of the 
failure. Investigation revealed that in each case, moisture had entered 
the area between the outer cylinder of the MLG and a mating bushing. 
The effects of such moisture subsequently caused stress corrosion 
cracking. This condition, if not detected and corrected in a timely 
manner, could cause more fractures of the outer cylinder of the aft 
trunnion, which could result in the loss of the MLG.
    The FAA has reviewed and approved Boeing Service Letter 767-SL-32-
067, dated August 4, 1995, which describes the following procedures:
    1. Performing repetitive visual inspections to determine if the 
fillet seal of the outer cylinder aft trunnion is cracked or missing;
    2. Removing the fillet seal, solvent-cleaning the adjacent area, 
applying corrosion inhibiting compound (CIC), 

[[Page 47690]]
and visually inspecting to detect corrosion, if any fillet seal is 
found cracked or missing; and
    3. Re-applying CIC and greasing, if no corrosion is detected, or 
repairing the aft trunnion, if any corrosion is detected. 
Accomplishment of this repair eliminates the need for the repetitive 
inspections.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other Boeing Model 767 series airplanes of the same 
type design, this AD is being issued to prevent stress corrosion 
cracking, which could result in fractures of the outer cylinder aft 
trunnion and the subsequent loss of the MLG. This AD requires visual 
inspections to determine if the fillet seal of the outer cylinder aft 
trunnion is cracked or missing, and the correction of any discrepancy 
or follow-on actions, if necessary. Repairing the aft trunnion 
constitutes terminating action for the repetitive inspection 
requirements. The actions are required to be accomplished in accordance 
with the service letter described previously.
    Operators should note that this AD requires repetitive application 
of CIC and grease every 500 flight hours, rather than at the 2A check 
interval (1,000 flight hours), as recommended in the service letter. 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 susceptibility of the subject 
area to a high velocity of water spray (such as, landing on wet 
runways, high pressure washing, etc.), which could lead to the 
accumulation of water and subsequent stress corrosion cracking of the 
outer cylinder of the aft trunnion.
    The FAA considers this AD to be interim action. The manufacturer 
has advised that it is developing a modification that will prevent 
future occurrences of this unsafe condition. Once this modification is 
developed, approved, and available, the FAA may consider additional 
rulemaking.
    As a result of recent communications with the Air Transport 
Association (ATA) of America, the FAA has learned that, in general, 
some operators may misunderstand the legal effect of AD's on airplanes 
that are identified in the applicability provision of the AD, but that 
have been altered or repaired in the area addressed by the AD. The FAA 
points out that all airplanes identified in the applicability provision 
of an AD are legally subject to the AD. If an airplane has been altered 
or repaired in the affected area in such a way as to affect compliance 
with the AD, the owner or operator is required to obtain FAA approval 
for an alternative method of compliance with the AD, in accordance with 
the paragraph of each AD that provides for such approvals. A note has 
been included in this rule to clarify this long-standing requirement.
    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 
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 95-NM-149-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 U.S.C. 106(g), 40101, 40113, 44701.


Sec. 39.13  [Amended]

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

95-19-10  Boeing: Amendment 39-9372. Docket 95-NM-149-AD.

    Applicability: All Model 767 series airplanes, certificated in 
any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 (d) 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 

[[Page 47691]]
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 stress corrosion cracking, which could result in 
fractures of the outer cylinder aft trunnion and the subsequent loss 
of the main landing gear (MLG), accomplish the following:
    (a) Within 5-\1/2\ years since the last overhaul of the MLG or 
since the date of manufacture of the MLG (for MLG's that have not 
been overhauled), or within 60 days after the effective date of this 
AD, whichever occurs later: Perform a visual inspection to determine 
if the fillet seal of the outer cylinder aft trunnion is cracked or 
missing, in accordance with Boeing Service Letter 767-SL-32-067, 
dated August 4, 1995. For the purposes of this AD, fillet seals are 
not considered to be ``cracked'' if cracks are found in the fillet 
seal paint only (where the fillet seal itself is not cracked).
    (b) If no cracked fillet seal is found during the inspection 
required by paragraph (a) of this AD, repeat the inspection 
thereafter at intervals not to exceed 18 months.
    (c) If any fillet seal is found to be cracked or missing during 
the inspection required by paragraph (a) of this AD, prior to 
further flight, remove the fillet seal (if present), clean the 
adjacent area with a solvent, apply corrosion inhibiting compound 
(CIC), and perform a visual inspection to detect corrosion, in 
accordance with Boeing Service Letter 767-SL-32-067, dated August 4, 
1995.
    (1) If no corrosion is detected, prior to the accumulation of 
500 flight hours, reapply CIC and grease in accordance with the 
service letter. Thereafter, repeat the application of CIC and grease 
at intervals not to exceed 500 flight hours.
    (2) If any corrosion is detected, prior to further flight, 
repair the aft trunnion in accordance with the service letter. 
Accomplishment of this repair constitutes terminating action for the 
repetitive inspection requirements of this AD.
    (d) 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.

    (e) 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.
    (f) The actions shall be done in accordance with Boeing Service 
Letter 767-SL-32-067, dated August 4, 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.
    (g) This amendment becomes effective on September 29, 1995.

    Issued in Renton, Washington, on September 7, 1995.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-22715 Filed 9-13-95; 8:45 am]
BILLING CODE 4910-13-U