[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
