[Federal Register Volume 60, Number 4 (Friday, January 6, 1995)]
[Proposed Rules]
[Pages 2036-2041]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-306]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 94-NM-28-AD]
Airworthiness Directives; Boeing Model 767 Series Airplanes
Equipped With General Electric CF6-80C2 Series Engines
AGENCY: Federal Aviation Administration, DOT.
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: This document proposes the supersedure of 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. This action would add
requirements for installation of a terminating modification on
airplanes equipped with General Electric CF6-80C2 series engines, and
repetitive operational checks of the electro-mechanical brake and the
cone brake of the center drive unit following accomplishment of the
modification. This action also would remove airplanes equipped with
Rolls-Royce RB211-524 series engines from the applicability of the
existing AD. This proposal is 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 specified by the proposed AD are intended to prevent
possible discrepancies that exist in the current thrust reverser
control system, which could result in an inadvertent deployment of a
thrust reverser during flight.
DATES: Comments must be received by March 3, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation
Administration (FAA), Transport Airplane Directorate, ANM-103,
Attention: Rules Docket No. 94-NM-28-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056. Comments may be inspected at this location
between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal
holidays.
The service information referenced in the proposed rule 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.
FOR FURTHER INFORMATION CONTACT: Lanny Pinkstaff, 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:
Comments Invited
Interested persons are invited to participate in the making of the
proposed 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 above. All
communications received on or before the closing date for comments,
specified above, will be considered before taking action on the
proposed rule. The proposals contained in this notice may be changed in
light of the comments received.
Comments are specifically invited on the overall regulatory,
economic, environmental, and energy aspects of the proposed 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 summarizing each FAA-public contact concerned with
the substance of this proposal will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments
submitted in response to this notice must submit a self-addressed,
stamped postcard on which the following statement is made: ``Comments
to Docket Number 94-NM-28-AD.'' The postcard will be date stamped and
returned to the commenter.
Availability of NPRMs
Any person may obtain a copy of this NPRM by submitting a request
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules
Docket No. 94-NM-28-AD, 1601 Lind Avenue, SW., Renton, Washington
98055-4056.
Discussion
On October 7, 1991, the FAA issued AD 91-22-02, amendment 39-8062
(56 FR 51638, October 15, 1991), applicable to Boeing Model 767 series
airplanes equipped with Rolls-Royce RB211-524 series engines or General
Electric CF6-80C2 series engines, to require tests, inspections, and
adjustments of the thrust reverser system. That action was prompted by
an ongoing design review, resulting from an accident investigation from
which it had been determined that, prior to the accident, the airplane
apparently experienced an uncommanded in-flight deployment of a thrust
reverser. Deployment of a thrust reverser in flight could result in
reduced controllability of the airplane. The requirements of that AD
are intended to ensure the integrity of the fail-safe features of the
thrust reverser system by preventing possible discrepancies in the
thrust reverser control system that can result in the inadvertent
deployment of a thrust reverser during flight.
Since the issuance of AD 91-22-02, the FAA issued AD 94-17-03,
amendment 39-8998 (59 FR 41647, August 15, 1994). AD 94-17-03 was
issued to require inspections, adjustments, and functional checks of
the thrust reverser system; installation of a terminating modification;
and repetitive operational checks of the gearbox locks and the air
motor brake following accomplishment of the terminating modification on
Model 767 series airplanes equipped with Rolls-Royce RB211-524 series
engines. In the preamble to AD 94-17-03, the FAA stated it would
consider superseding AD 91-22-02 to remove the requirements for Model
767 series airplanes equipped with Rolls-Royce RB211-524 series engines
from that AD, to specify that those requirements are contained in AD
94-17-03, and to require accomplishment of a terminating modification
for Model 767 series airplanes equipped with General Electric CF6-80C2
series engines. This action proposes such requirements.
Explanation of Relevant Service Information
Since the issuance of AD 91-22-02, the FAA has reviewed and
approved Boeing Service Bulletin 767-78-0047, Revision 3, dated July
28, 1994. The original issue of the service bulletin was cited in AD
91-22-02 as the appropriate source of service information for
performing various tests, inspections, and adjustments required by that
AD. Revision 3 of the service bulletin revises certain procedures
specified in the Accomplishment Instructions of earlier revisions of
the service bulletin. (The FAA has referenced this latest revision of
the service bulletin as the appropriate source of service information
for accomplishment of those actions after the effective date of this
proposed AD.)
The FAA also has reviewed and approved Boeing Service Bulletin 767-
78-0063, Revision 2, dated April 28, [[Page 2037]] 1994, which
describes procedures for installation of a third locking system on the
thrust reversers on Model 767 series airplanes equipped with General
Electric CF6-80C2 series engines to minimize the possibility of an
uncommanded in-flight deployment of the thrust reversers. This
modification involves the following:
1. installing fuselage-to-wing pressure seal doublers;
2. routing and installing new ships wiring;
3. installing the tray assembly and thrust reverser relay module on
the E1-4 or E2-6 shelf;
4. installing circuit breakers, filler patches, bus bars, and a
relay in the P11 panel;
5. removing, reworking, and installing the M966 autothrottle
microswitch pack;
6. Installing the left and right thrust reverser locks with
associated wire bundles on both engines; and
7. Performing a functional test of the thrust reverser system.
The FAA has determined that accomplishing this modification in
accordance with the service bulletin will positively address the
identified unsafe condition with regard to those airplanes equipped
with General Electric CF6-80C2 series engines.
Explanation of the Proposed Requirements
Since an unsafe condition has been identified that is likely to
exist or develop on other products of this same type design, the
proposed AD would supersede AD 91-22-02 to continue to require tests,
inspections, and adjustments of the thrust reverser system on Model 767
series airplanes equipped with General Electric CF6-80C2 series
engines. This proposed AD would add a requirement to install the
terminating modification, described above. The tests, inspections,
adjustments, and terminating modification would be required to be
accomplished in accordance with the Boeing service bulletins described
previously.
In addition, the FAA has determined that operational checks of the
electro-mechanical brake and the cone brake of the center drive unit
are necessary to provide an adequate level of safety and to ensure the
effectiveness of the terminating modification following its
installation in addressing the unsafe condition identified in this
proposed AD. Procedures for accomplishment of the proposed operational
checks are specified in Appendix 1 (including Figure 1) of this
proposed AD.
Accomplishment of the terminating modification and operational
checks would constitute terminating action for the tests, inspections,
and adjustments currently required by AD 91-22-02.
This proposed AD also would remove airplanes equipped with Rolls-
Royce RB211-524 series engines from the applicability of AD 91-22-02.
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 notice to clarify this requirement.
Cost Impact
There are approximately 135 Boeing Model 767 series airplanes
equipped with General Electric CF6-80C2 series engines in the worldwide
fleet. The FAA estimates that 39 airplanes of U.S. registry would be
affected by this proposed AD.
The tests, inspections, and adjustments that were previously
required by AD 91-22-02, and retained in this AD, take approximately 30
work hours per airplane to accomplish, at an average labor rate of $60
per work hour. Based on these figures, the total cost impact on U.S.
operators of the currently required tests, inspections, and adjustments
that would be retained in AD is estimated to be $70,200, or $1,800 per
airplane, per inspection cycle.
The terminating modification proposed by this AD would take
approximately 786 work hours per airplane to accomplish, at an average
labor rate of $60 per work hour. Required parts would be provided by
the manufacturer at no cost to the operator. The repetitive operational
checks proposed by this AD would take approximately 2 work hours per
airplane to accomplish at an average labor rate of $60 per work hour.
Based on these figures, the total cost impact of the terminating
modification and repetitive operational checks proposed in this AD on
U.S. operators is estimated to be $1,843,920, or $47,280 per airplane.
The number of required work hours for each requirement of this
proposed AD, as indicated above, is presented as if the accomplishment
of the actions were to be conducted as ``stand alone'' actions.
However, in actual practice, these actions for the most part would be
accomplished coincidentally or in combination with normally scheduled
airplane inspections and other maintenance program tasks. Therefore,
the actual number of necessary additional work hours will be minimal in
many instances. Additionally, any costs associated with special
airplane scheduling will be minimal.
The FAA recognizes the large number of work hours required to
accomplish the proposed modification. However, the 3-year compliance
time proposed in paragraph (c) of this AD should allow the modification
to be accomplished coincidentally with scheduled major airplane
inspection and maintenance activities, thereby minimizing the costs
associated with special airplane scheduling.
Regulatory Impact
The regulations proposed herein would 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
proposal would not have sufficient federalism implications to warrant
the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this proposed
regulation (1) is not a ``significant regulatory action'' under
Executive Order 12866; (2) is not a ``significant rule'' under the DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);
and (3) if promulgated, will not have a significant economic impact,
positive or negative, on a substantial number of small entities under
the criteria of the Regulatory Flexibility Act. A copy of the draft
regulatory evaluation prepared for this action is contained in the
Rules Docket. A copy of it may be obtained by contacting the Rules
Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
The Proposed Amendment
Accordingly, pursuant to the authority delegated to me by the
[[Page 2038]] Administrator, the Federal Aviation Administration
proposes to amend 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. App. 1354(a), 1421 and 1423; 49 U.S.C.
106(g); and 14 CFR 11.89.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by removing amendment 39-8062 (56 FR
51638, October 15, 1991), and by adding a new airworthiness directive
(AD), to read as follows:
Boeing: Docket 94-NM-28-AD. Supersedes AD 91-22-02, Amendment 39-
8062.
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) 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 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.
Appendix--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. Electro-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 pounds-inches.
(2) Do a check of the elctro-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. [[Page 2039]]
(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.
CAUTION: DO NOT USE MORE THAN 130 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 2040]]
[GRAPHIC][TIFF OMITTED]TP06JA95.000
BILLING CODE 4910-13-C [[Page 2041]]
Issued in Renton, Washington, on December 30, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-306 Filed 1-5-95; 8:45 am]
BILLING CODE 4910-13-U
