[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]
BILLING CODE 4910-13-P