[Federal Register Volume 61, Number 56 (Thursday, March 21, 1996)]
[Rules and Regulations]
[Pages 11541-11543]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-6540]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 96-NM-50-AD; Amendment 39-9546; AD 96-06-09]
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 three Boeing Model 767 series airplanes, serial
numbers 26847, 27048, and 27049. This action requires a functional
check of the trailing edge flap drive bypass valve, and eventual
replacement of the control valve module for the trailing edge flaps
with an improved module. This amendment is prompted by reports of
failure of the bypass valve motor in the control valve module of the
trailing edge flaps due to hydraulic fluid contamination. The actions
specified in this AD are intended to prevent such failure, which could
result in loss of shutdown protection for the trailing edge flap drive;
this condition could result in reduced controllability of the airplane
in the event of uncommanded or asymmetrical flap motion.
DATES: Effective April 5, 1996.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of April 5, 1996.
Comments for inclusion in the Rules Docket must be received on or
before May 20, 1996.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 96-NM-50-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.
[[Page 11542]]
FOR FURTHER INFORMATION CONTACT: Susan Letcher, Aerospace Engineer,
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft
Certification Office, 1601 Lind Avenue SW., Renton, Washington;
telephone (206) 227-2670; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION: On September 27, 1993, the FAA issued AD 93-
19-05, amendment 39-8703 (58 FR 54940, October 25, 1993), which is
applicable to Boeing Model 767 series airplanes, line positions 001
through 402 inclusive. That AD requires (initially) various functional
checks of:
1. the leading edge slat shutoff valve,
2. the trailing edge flap drive bypass valve,
3. the leading edge slat long term shutoff control, and
4. the leading edge slat drive mechanical rigging.
In addition, that AD requires installation of terminating
modifications for the required functional checks. One of these
modifications involves replacing the bypass valve motor of the control
valve module for the trailing edge flaps.
AD 93-19-05 was prompted by a report of an uncommanded slat
extension during cruise, and several instances of an inoperative
trailing edge flap bypass valve motor. These instances were attributed
to hydraulic fluid in the bypass valve motor. The requirements of that
AD are intended to prevent uncommanded deployment of leading edge
slats, which could result in structural damage to the wing and
consequent degradation of flight control. Additionally, the
requirements of that AD are intended to ensure shutdown protection for
the trailing edge flap drive in the event of uncommanded or
asymmetrical flap motion.
Since the issuance of AD 93-19-05, the manufacturer has advised the
FAA that three airplanes (those having serial numbers 26847, 27048, and
27049) were delivered on which the replacement of the bypass valve
motor in the control valve module for the trailing edge flaps had not
been accomplished during production. Those three airplanes were not
included in the applicability of AD 93-19-05; however, they are subject
to the same unsafe condition addressed by that AD. The FAA has
determined that loss of shutdown protection for the trailing edge flap
drive due to hydraulic fluid contamination of the bypass valve motor
could occur on these three airplanes.
The FAA has reviewed and approved Boeing Service Bulletin 767-
27A0094, Revision 5, dated June 9, 1994, which describes (among other
actions) procedures to perform a one-time functional check of the
bypass valve of the trailing edge flap drive.
The FAA has also reviewed and approved Boeing Service Bulletin 767-
27-0138, dated August 17, 1995, which describes procedures for
replacement of the control valve module for the trailing edge flaps
with an improved module on the three airplanes having serial numbers
26847, 27048, and 27049. The bypass valve motor in the improved module
was redesigned to ensure that the motor is hermetically sealed.
Accomplishment of this replacement will prevent hydraulic fluid
contamination.
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 loss of shutdown
protection for the trailing edge flap drive, which could result in
reduced controllability of the airplane in the event of uncommanded or
asymmetrical flap motion. This AD requires a one-time functional check
of the trailing edge flap drive bypass valve, and eventual replacement
of the control valve module for the trailing edge flaps with an
improved module. The actions are required to be accomplished in
accordance with the service bulletins described previously. This AD
applies only to airplanes having serial numbers 26847, 27048, and
27049.
[Note: The FAA's normal policy is that when an AD requires a
substantive change, such as a change (expansion) in its
applicability, the ``old'' AD is superseded by removing it from the
system and a new AD is added. In the case of this AD action, the FAA
normally would have proposed superseding AD 93-19-05 to expand its
applicability to include the three additional affected airplanes.
However, in reconsideration of the entire fleet size that would be
affected by a supersedure action, and the consequent workload
associated with revising maintenance record entries, the FAA has
determined that a less burdensome approach is to issue a separate AD
applicable only to the three additional airplanes. This AD does not
supersede AD 93-19-05; airplanes listed in the applicability of AD
93-19-05 are required to continue to comply with the requirements of
that AD. This AD is a separate AD action, and is applicable only to
airplanes having serial numbers 26847, 27048, and 27049.]
Operators should note that the manufacturer's recommended
compliance time for accomplishment of the functional check is within
400 flight hours after receipt of the service bulletin. While the FAA
agrees that 400 flight hours would normally be an appropriate
compliance time, this AD specifies a compliance time of 25 days after
the effective date of this AD. This compliance time was developed by
taking into account the date that the initial service bulletin
recommended (September 28, 1989) for accomplishment of the actions and
the time that has elapsed since that date. The FAA considered not only
the manufacturer's recommendation, but the degree of urgency associated
with addressing the subject unsafe condition, as well as the time
necessary to perform the functional check (1 work hour). In light of
these factors, the FAA finds 25 days to be an appropriate compliance
time for initiating the required functional check.
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 96-NM-50-AD.'' The
[[Page 11543]]
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:
96-06-09 Boeing: Amendment 39-9546. Docket 96-NM-50-AD.
Applicability: Model 767 series airplanes, having serial number
26847, 27048, or 27049, 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 (d) 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 loss of shutdown protection for the trailing
edge flap drive, which could result in reduced controllability of
the airplane in the event of uncommanded or asymmetrical flap
motion, accomplish the following:
(a) Within 25 days after the effective date of this AD, perform
a one-time functional check to ensure that the bypass valve motor in
the control valve module for the trailing edge flaps is operational,
in accordance with Part II of the Accomplishment Instructions of
Boeing Service Bulletin 767-27A0094, Revision 5, dated June 9, 1994.
If a failed bypass valve motor is found, prior to further flight,
accomplish the replacement required by paragraph (b) of this AD.
(b) Within 60 days after the effective date of this AD, replace
the control valve module for the trailing edge flaps with an
improved module having a redesigned bypass valve motor that is
hermetically sealed, in accordance with Boeing Service Bulletin 767-
27-0138, dated August 17, 1995.
(c) As of the effective date of this AD, no person shall install
either a control valve module, part number S256T005-7, or a bypass
valve, part number S256T005-4, on any airplane.
(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 functional check shall be done in accordance with Boeing
Service Bulletin 767-27A0094, Revision 5, dated June 9, 1994. The
replacement shall be done in accordance with Boeing Service Bulletin
767-27-0138, dated August 17, 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 April 5, 1996.
Issued in Renton, Washington, on March 13, 1996.
James V. Devany,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-6540 Filed 3-20-96; 8:45 am]
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