[Federal Register Volume 61, Number 46 (Thursday, March 7, 1996)]
[Rules and Regulations]
[Pages 9091-9096]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-5253]
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[[Page 9092]]
DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-NM-28-AD; Amendment 39-9528; AD 95-13-12 R1]
Airworthiness Directives; Boeing Model 767 Series Airplanes
Equipped With General Electric CF6-80C2 Series Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; correction.
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SUMMARY: This amendment clarifies information in an existing
airworthiness directive (AD), applicable to certain Boeing Model 767
series airplanes, that currently requires tests, inspections, and
adjustments of the thrust reverser system. That AD also requires
installation of a terminating modification and repetitive follow-on
actions. The actions specified in that AD are intended to prevent
possible discrepancies that exist in the current thrust reverser
control system, which could result in inadvertent deployment of a
thrust reverser during flight. This amendment clarifies the
requirements of the current AD by specifying a revised number of pound-
inches of torque operators should use when performing the torque check
of the cone brake of the center drive unit (CDU). This amendment is
prompted by information from the manufacturer that a current
requirement of the AD requires clarification.
DATES: Effective August 18, 1995.
The incorporation by reference of certain publications listed in
the regulations was approved previously by the Director of the Federal
Register as of August 18, 1995 (60 FR 36976, July 19, 1995).
FOR FURTHER INFORMATION CONTACT: Nancy Hanowski, Aerospace Engineer,
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate,
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056; telephone (206) 227-2684; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION: On June 22, 1995, the FAA issued AD 95-13-
12, amendment 39-9292 (60 FR 36976, July 19, 1995), which is applicable
to certain Boeing Model 767 series airplanes. That AD requires tests,
inspections, and adjustments of the thrust reverser system. That AD
also requires installation of a terminating modification and repetitive
follow-on actions. That action was prompted by the identification of a
modification that ensures that the level of safety inherent in the
original type design of the thrust reverser system is further enhanced.
The actions required by that AD are intended to prevent possible
discrepancies that exist in the current thrust reverser control system,
which could result in inadvertent deployment of a thrust reverser
during flight.
Since the issuance of that AD, the manufacturer has advised the FAA
that a torque check value specified in Appendix 1 of the AD requires
clarification. The procedures originally provided to the FAA for
accomplishment of a torque check of the cone brake of the center drive
unit (CDU) indicate that operators should not use more than 130 pound-
inches of torque when performing the check. While using 130 pound-
inches of torque would not damage the CDU, the manufacturer has advised
the FAA that 100 pound-inches of torque is the appropriate value.
Accomplishing the torque check up to 100 pound-inches is intended to
identify a CDU having a decaying torque level due to a soft shaft
problem, while at the same time not exposing the brake to unnecessarily
high torque/stress levels.
Action is taken herein to clarify this requirement of AD 95-13-12
and to correctly add the AD as an amendment to section 39.13 of the
Federal Aviation Regulations (14 CFR 39.13).
The final rule is being reprinted in its entirety for the
convenience of affected operators. The effective date remains August
18, 1995.
Since this action only clarifies a current requirement, it has no
adverse economic impact and imposes no additional burden on any person.
Therefore, notice and public procedures hereon are unnecessary.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Correction
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 removing amendment 39-9292 (60 FR
36976, July 19, 1995), and by adding a new airworthiness directive
(AD), amendment 39-9528, to read as follows:
95-13-12 R1 Boeing: Amendment 39-9528. Docket 94-NM-28-AD.
Revises AD 95-13-12, Amendment 39-9292.
Applicability: Model 767 series airplanes equipped with General
Electric CF6-80C2 series engines, 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 (f) 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 ensure the integrity of the fail-safe features of the thrust
reverser system, accomplish the following:
(a) Within 30 days after October 15, 1991 (the effective date of
AD 91-22-02, amendment 39-8062), perform tests, inspections, and
adjustments of the thrust reverser system in accordance with Boeing
Service Bulletin 767-78-0047, dated August 22, 1991; Revision 1,
dated March 26, 1992; Revision 2, dated January 21, 1993; or
Revision 3, dated July 28, 1994. After the effective date of this
AD, those actions shall be accomplished only in accordance with
Revision 3 of the service bulletin.
(1) Except as provided by paragraph (a)(2) of this AD, repeat
all tests and inspections thereafter at intervals not to exceed
3,000 flight hours until the modification required by paragraph (c)
of this AD is accomplished.
(2) Repeat the check of the grounding wire for the Directional
Pilot Valve (DPV) of the thrust reverser in accordance with the
service bulletin at intervals not to exceed 1,500 flight hours, and
whenever maintenance action is taken that would disturb the DPV
grounding circuit, until the modification required by paragraph (c)
of this AD is accomplished.
(b) If any of the tests and/or inspections required by paragraph
(a) of this AD cannot be successfully performed, or if those tests
and/or inspections result in findings that are unacceptable in
accordance with Boeing Service Bulletin 767-78-0047, dated August
22, 1991; Revision 1, dated March 26, 1992; Revision 2, dated
January 21, 1993; or Revision 3, dated July 28, 1994; accomplish
paragraphs (b)(1) and (b)(2) of this AD. After the effective date of
this AD, the actions required by paragraphs (b)(1) and (b)(2) shall
be accomplished only in accordance with Revision 3 of the service
bulletin.
(1) Prior to further flight, deactivate the associated thrust
reverser in accordance with Section 78-31-1 of Boeing Document
D630T002, ``Boeing 767 Dispatch Deviation
[[Page 9093]]
Guide,'' Revision 9, dated May 1, 1991; or Revision 10, dated
September 1, 1992. After the effective date of this AD, this action
shall be accomplished only in accordance with Revision 10 of the
Boeing document. No more than one reverser on any airplane may be
deactivated under the provisions of this paragraph.
(2) Within 10 days after deactivation of any thrust reverser in
accordance with this paragraph, the thrust reverser must be repaired
in accordance with Boeing Service Bulletin 767-78-0047, dated August
22, 1991; Revision 1, dated March 26, 1992; Revision 2, dated
January 21, 1993; or Revision 3, dated July 28, 1994. After the
effective date of this AD, the repair shall be accomplished only in
accordance with Revision 3 of the service bulletin. Additionally,
the tests and/or inspections required by paragraph (a) of this AD
must be successfully accomplished; once this is accomplished, the
thrust reverser must then be reactivated.
(c) Within 3 years after the effective date of this AD, install
a third locking system on the left- and right-hand engine thrust
reversers in accordance with Boeing Service Bulletin 767-78-0063,
Revision 2, dated April 28, 1994.
Note 2: The Boeing service bulletin references General Electric
Service Bulletin 78-135 as an additional source of service
information for accomplishment of the third locking system on the
thrust reversers. However, the Boeing service bulletin does not
specify the appropriate revision level for the General Electric
service bulletin. The appropriate revision level for the General
Electric service bulletin to be used in conjunction with the Boeing
service bulletin is Revision 3, dated August 2, 1994.
(d) Within 4,000 flight hours after accomplishing the
modification required by paragraph (c) of this AD, or within 4,000
flight hours after the effective date of this AD, whichever occurs
later; and thereafter at intervals not to exceed 4,000 flight hours;
perform operational checks of the electro-mechanical brake and the
cone brake of the center drive unit in accordance with Appendix 1
(including Figure 1) of this AD.
(e) Accomplishment of the modification and periodic operational
checks required by paragraphs (c) and (d) of this AD constitutes
terminating action for the tests, inspections, and adjustments
required by paragraph (a) of this AD.
(f) 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 3: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Seattle ACO.
(g) 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.
(h) Certain actions shall be done in accordance with the
following Boeing service bulletins, which contain the specified
effective pages:
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Service bulletin referenced Revision level
and date Page No. shown on page Date shown on page
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767-78-0047, Revision 1, 1-33................................ 1.............. March 26, 1992.
March 26, 1992.
767-78-0047, Revision 2, 1-2, 4, 12-13, 20-32................ 2-............. January 21, 1993.
January 21, 1993.
3, 5, 10-11, 14-15, 17-19........... 1.............. March 26, 1992.
6-9, 16............................. Original....... August 22, 1991.
767-78-0047, Revision 3, July 1-32................................ 3.............. July 28, 1994.
28, 1994.
767-78-0063, Revision 2, 1-292............................... 2.............. April 28, 1994.
April 28, 1994.
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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, as of August 18, 1995 (60 FR 36976, July 19, 1995). 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.
(i) This amendment is effective on August 18, 1995.
Appendix 1
Thrust Reverser Electro-Mechanical Brake and CDU Cone Brake Test
1. General
A. This procedure contains steps to do two checks:
(1) A check of the holding torque of the electro-mechanical
brake
(2) A check of the holding torque of the CDU cone brake.
2. Electroc-Mechanical Brake and CDU Cone Brake Torque Check (Fig. 1)
A. Prepare to do the checks:
(1) Open the fan cowl panels.
B. Do a check of the torque of the electro-mechanical brake:
(1) Do a check of the running torque of the thrust reverser
system:
(a) Manually extend the thrust reverser six inches and measure
the running torque.
(1) Make sure the torque is less than 10 pound-inches.
(2) Do a check of the electro-mechanical brake holding torque:
(a) Make sure the thrust reverser translating cowl is extended
at least one inch.
(b) Make sure the CDU lock handle is released.
(c) Pull down on the manual release handle on the electro-
mechanical brake until the handle fully engages the retaining clip.
Note: This will lock the electro-mechanical brake.
(d) With the manual drive lockout cover removed from the CDU,
install a \1/4\-inch extension tool and dial-type torque wrench into
the drive pad.
Note: You will need a 24-inch extension to provide adequate
clearance for the torque wrench.
(e) Apply 90 pound-inches of torque to the system.
(1) The electro-mechanical brake system is working correctly if
the torque is reached before you turn the wrench 450 degrees (1\1/4\
turns).
(2) If the flexshaft turns more than 450 degrees before you
reach the specified torque, you must replace the long flexshaft
between the CDU and the upper angle gearbox.
(3) If you do not get 90 pound-inches of torque, you must
replace the electro-mechanical brake.
(f) Release the torque by turning the wrench in the opposite
direction until you read zero pound-inches.
(1) If the wrench does not return to within 30 degrees of
initial starting point, you must replace the long flexshaft between
the CDU and upper angle gearbox.
(3) Fully retract the thrust reverser.
C. Do a check of the torque of the CDU cone brake:
(1) Pull up on the manual release handle to unlock the electro-
mechanical brake.
(2) Pull the manual brake release lever on the CDU to release
the cone brake.
Note: This will release the pre-load tension that may occur
during a stow cycle.
(3) Return the manual brake release lever to the locked position
to engage the cone brake.
(4) Remove the two bolts that hold the lockout plate to the CDU
and remove the lockout plate.
(5) Install a \1/4\-inch drive and a dial-type torque wrench
into the CDU drive pad.
[[Page 9094]]
Caution: Do not use more than 100 pound-inches of torque when
you do this check. Excessive torque will damage the CDU.
(6) Turn the torque wrench to try to manually extend the
translating cowl until you get at least 15 pound-inches.
Note: The cone brake prevents movement in the extend direction
only. If you try to measure the holding torque in the retract
direction, you will get a false reading.
(a) If the torque is less than 15 pound-inches, you must replace
the CDU.
D. Return the airplane to its usual condition:
(1) Fully retract the thrust reverser.
(2) Pull down on the manual release handle on the electro-
mechanical brake until the handle fully engages the retaining clip.
Note: This will lock the electro-mechanical brake.
(3) Close the fan cowl panels.
BILLING CODE 4910-13-U
[[Page 9095]]
[GRAPHIC] [TIFF OMITTED] TR07MR96.038
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BILLING CODE 4910-13-C
Issued in Renton, Washington, on February 27, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 96-5253 Filed 3-6-96; 8:45 am]
BILLING CODE 4910-13-U