# Boeing Alert Service Bulletin 767-78A0088: No revision named

- Rights: © The Boeing Company. Filed by the FAA in regulations.gov docket FAA-2012-1318; AD 2014-05-16 incorporates this document by reference. Not covered by OpenAirDocs’ CC0 dedication.
- Document: [Boeing Alert Service Bulletin 767-78A0088](https://openairdocs.org/service-documents/boeing/767-78a0088.md)
- Title as filed: U.S. DOT/FAA - SB-767-78A0088-00
- Pages: 13
- PDF: https://openairdocs.org/files/sha256/99/93/9993c3fbb4811ce27b9a30c9c006e62a71d6655e3f19cee7e21b975a9de657c3
- Page: https://openairdocs.org/service-documents/boeing/767-78a0088/file/9993c3fbb481

## Text

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### Page 1

Commercial
Airplane
Group
767
Service Bulletin
ALERT
Number: 767-78A0088 SummaryDate: April 19, 2001
ATA System: 7800
SUBJECT: EXHAUST (CF6-80C2 Engines) - Thrust Reverser - Thrust Reverser Control System - Center
Drive Unit (CDU) Cone Brake and Electro-Mechanical Brake Integrity Tests
CONCURRENT REQUIREMENTS
None
BACKGROUND
This inspection will make sure that the center drive
unit (CDU) cone brake and the Thrust Reverser
Actuation System (TRAS) brake have the holding
torque required to prevent any uncommanded thrust
reverser sleeve movement.
The CDU cone brake and the TRAS brake are
primary safety devices required to prevent
inadvertent thrust reverser sleeve movement. To
meet the system reliability requirements, periodic
torque checks are required to ensure the integrity of
these locking devices. A failure of either of these
locks is not detected during normal operation. The
torque check intervals have been determined
through industry-wide accepted probability and
reliability methods.
The TRAS lock is a solenoid activated disk brake
this is connected to the upper angle gearbox by a
flexible drive shaft. The brake is released when 28
VDC is applied from the control circuit and is locked
at all other times. Low torque can be the result of a
brake or flexible shaft failure.
The CDU cone brake is a spring load, unidirectional
device that prevent rotation of the air motor in the
deploy direction. The cone brake always allows the
air motor to rotate in the stow direction. The brake
is disengaged when the directional control valve
actuator piston is commanded to the deploy position
from the control circuit.
ACTION
On each thrust reverser half, do a functional test of
the Electro-Mechanical brake and CDU cone brake
to verify the holding torque.
EFFECTIVITY
All 767-400ER airplanes powered by CF6-80C2
engines.
COMPLIANCE
Boeing recommends the operators do this service
bulletin within 650 flight hours after receipt of this
service bulletin.
Boeing recommends the operators repeat the
Electro-Mechanical brake and CDU cone brake tests
every 1,000 flight hours.
Federal Aviation Administration (FAA) Airworthiness
Directive (AD) 2000-09-04, Amendment 39-11712,
is related to this service bulletin.
INDUSTRY SUPPORT INFORMATION
Boeing warranty remedies are not available for the
inspection given in this service bulletin.
MANPOWER
Total Man-hours - 6 for each airplane
Elapsed Time - 3 Hours
MATERIAL INFORMATION
None
767-78A0088
Summary Page 1 of 2

### Page 2

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
ELECTRO−MECHANICAL BRAKE
DO A FUNCTIONAL TEST ON THE
FOR EACH THRUST REVERSER HALF:
DO A FUNCTIONAL TEST ON THE
FOR EACH THRUST REVERSER HALF:
CENTER DRIVE UNIT (CDU) CONE BRAKE
RIGHT SIDE OPPOSITE
LEFT SIDE SHOWN,
V41557
April 19, 2001 767-78A0088
Summary Page 2 of 2

### Page 3

Commercial
Airplane
Group
767
Service Bulletin
ALERT
Number: 767-78A0088
Date: April 19, 2001
ATA System: 7800
SUBJECT: EXHAUST (CF6-80C2 Engines) - Thrust Reverser - Thrust Reverser Control System - Center
Drive Unit (CDU) Cone Brake and Electro-Mechanical Brake Integrity Tests
1. PLANNING INFORMATION
A. Effectivity
NOTE: * THIS EFFECTIVITY INCLUDES ALL FUTURE 767-400ER AIRPLANES WITH CF6-80C2
ENGINES, EVEN IF THEY ARE NOT LISTED IN THIS SECTION.
1. Airplanes
Refer to Service Bulletin Index Document D624T001, Part 3 for Airplane Variable Number, Line
Number, and Serial Number data.
This service bulletin is for the airplanes shown below.
Airplane Models:
767-400ER
IDENTIFICATION BY CUSTOMER, CUSTOMER CODE, GROUP AND VARIABLE NUMBER *
CONTINENTAL AIRLINES (CAL)
VQ071-VQ075
DELTA AIR LINES (DAL)
VQ001-VQ016
IDENTIFICATION BY VARIABLE NUMBER
VQ001-VQ016 VQ071-VQ075
2. Spares Affected
None
April 19, 2001 767-78A0088
Page 1 of 10

### Page 4

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
B. Concurrent Requirements
None
C. Reason
This inspection will make sure that the center drive unit (CDU) cone brake and the Thrust Reverser
Actuation System (TRAS) brake have the holding torque required to prevent any uncommanded
thrust reverser sleeve movement.
The CDU cone brake and the TRAS brake are primary safety devices required to prevent inadvertent
thrust reverser sleeve movement. To meet the system reliability requirements, periodic torque
checks are required to ensure the integrity of these locking devices. A failure of either of these locks
is not detected during normal operation. The torque check intervals have been determined through
industry-wide accepted probability and reliability methods.
The TRAS lock is a solenoid activated disk brake this is connected to the upper angle gearbox by a
flexible drive shaft. The brake is released when 28 VDC is applied from the control circuit and is
locked at all other times. Low torque can be the result of a brake or flexible shaft failure.
The CDU cone brake is a spring load, unidirectional device that prevent rotation of the air motor in the
deploy direction. The cone brake always allows the air motor to rotate in the stow direction. The
brake is disengaged when the directional control valve actuator piston is commanded to the deploy
position from the control circuit.
D. Description
On each thrust reverser half, do a functional test of the Electro-Mechanical brake and CDU cone
brake to verify the holding torque.
An evaluation form is attached to this service bulletin. Please use this form to tell us what you think
of the quality of this service bulletin.
E. Compliance
Boeing recommends the operators do this service bulletin within 650 flight hours after receipt of this
service bulletin.
Boeing recommends the operators repeat the Electro-Mechanical brake and CDU cone brake tests
every 1,000 flight hours.
Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2000-09-04, Amendment
39-11712, is related to this service bulletin.
F. Approval
NOTE: Joint Airworthiness Requirements (JAR) compliance status may be found in the Service
Bulletin Index, Part 1.
This service bulletin was examined by the Federal Aviation Administration (FAA). The changes
specified in this service bulletin comply with the applicable Federal Aviation Regulations (FAR) and
are FAA approved. This service bulletin and the FAA approval were based on the airplane in its
original Boeing delivery configuration or as modified by other FAA approved Boeing changes.
If an airplane has a non-Boeing modification or repair that affects a component or system also
affected by this service bulletin, the operator is responsible for obtaining appropriate regulatory
agency approval before incorporating this service bulletin.
April 19, 2001 767-78A0088
2

### Page 5

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
This service bulletin has been approved by the FAA. In addition, the Manager of the FAA Seattle
Aircraft Certification Office approves the inspection and tests defined in this service bulletin as an
alternative method of compliance to the requirements of paragraphs (d)(2), (f) and (g) of AD
2000-09-04. All provisions of AD 2000-09-04 that are not specifically referenced in the above
sentence remain fully applicable and must be complied with.
G. Manpower
The table below shows an estimate of the man-hours necessary to do this change for each airplane.
This estimate is for direct labor only, done by an experienced crew. Adjust the estimate with operator
man-hour data if necessary. The estimate does not include lost time. These are some examples of
lost time:
- Time to adjust to the workplace
- Time to schedule the work
- Time to examine the work
- Time to cure the materials
- Time to make the parts
- Time to find the tools.
Task Number of Persons Man-Hours Elapsed Time (Hours)
Test 2 6 3
TOTAL FOR EACH AIRPLANE 6 3
H. Weight and Balance Changes
None
I. Electrical Load Data
Not changed
J. References
1. Existing Data:
a. 767 Maintenance Manual (AMM) Subject 71-11-04, 78-31-21
2. Data supplied with this service bulletin:
None
3. Installation Drawings Used in the Preparation of This Service Bulletin:
None
April 19, 2001 767-78A0088
3

### Page 6

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
K. Publications Changed
None
L. Interchangeability and Intermixability of Parts
Refer to Paragraph 2.E., Existing Parts Accountability, for interchangeability and intermixability
information.
April 19, 2001 767-78A0088
4

### Page 7

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
2. MATERIAL INFORMATION
A. Material - Price and Availability
None
B. Industry Support Information
Boeing warranty remedies are not available for the inspection given in this service bulletin.
C. Parts Necessary For Each Airplane
Parts and Materials Supplied by the Operator:
QTY Part Number Name
4 126784-() Center Drive Unit (a)
(a) Replace this part when the holding torque is less than 15 pound inches.
D. Parts Necessary to Change Spares
None
E. Existing Parts Accountability
None
F. Special Tooling - Price and Availability
None
G. Special Tooling Necessary to do this Service Bulletin
No special tools or equipment are necessary to do the change in this service bulletin. But,
maintenance and overhaul tools in the manuals given in Paragraph 1.J., References, can be
necessary. Examine operator tool supply to make sure all necessary tools are available.
April 19, 2001 767-78A0088
5

### Page 8

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
BLANK PAGE
April 19, 2001 767-78A0088
6

### Page 9

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
3. ACCOMPLISHMENT INSTRUCTIONS
GENERAL NOTES
1. The lettered paragraphs contain the tests to be accomplished at the specifies interval.
2. Obey all of the warnings and cautions given in the specified manual sections.
3. Repeat the Electro-Mechanical brake and CDU cone brake tests every 1,000 flight hours.
WORK INSTRUCTIONS
A. Do the functional test on both thrust reverser for the Electro-Mechanical brakes of both engines as
follows:
1. Open the engine fan cowl panels as shown in 767 Maintenance Manual Subject 71-11-04 or
your own equivalent procedure.
2. 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. Make sure
the torque is less than 10 pound-inches.
3. 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 (1-1/4 turns) 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, inspect the short flexshaft between the
upper angle gearbox and the electro-mechanical brake. If the flexshaft is twisted, broken
or otherwise damaged, replace the flexshaft and repeat (e). If you still 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 position direction until you read zero
pound-inches.
April 19, 2001 767-78A0088
7

### Page 10

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
1) If the wrench does not turn to within 30 degrees of initial starting point, you must replace
the long flexshaft between the CDU and upper angle gearbox.
4. Fully retract the thrust reverser.
5. Repeat this procedure on other reverser half and on the remaining engines.
6. End the Electro-Mechanical brake check.
B. Repeat the Electro-Mechanical brake test at 1,000 flight hours intervals
C. Do the functional test on both thrust reverser for the Center Drive Unit (CDU) cone brakes of both
engines as follows:
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. Refer to Figure 1
for location.
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. Refer
to Figure 1 for location.
4. Remove the two bolts that hold the lockout plate to the CDU and remove the lockout plate.
Refer to Figure 1 for location.
5. Install a 1/4-inch drive and a dial-type torque wrench into the CDU drive pad.
WARNING: Do not use more than 100 pound-inches of torque when carrying out 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 of torque.
NOTE: The cone brake prevents movement in the extend direction only. If you try to measure
the torque in the retract direction, you will get a false reading.
7. If the sleeve translates to deploy with a torque less than 15 pound inches you must replace the
CDU. Refer to 767 Maintenance Manual Subject 78-31-21.
8. Reinstall the lockout plate.
9. Fully retract the thrust reverser.
10. 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.
11. Repeat this procedure on other reverser half and on the remaining engines.
12. Close the engine fan cowl panels as shown in 767 Maintenance Manual Subject 71-11-04 or
your own equivalent procedure.
13. End the CDU cone brake check.
D. Repeat CDU cone brake test every 1,000 flight hours.
April 19, 2001 767-78A0088
8

### Page 11

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
FIGURE TABLE OF CONTENTS
Title Page
FIGURE 1. ELECTRO-MECHANICAL BRAKE, CDU MANUAL BRAKE RELEASE
LEVER, LOCKOUT PLATE AND DRIVE PAD LOCATIONS . . ........... 1 0
April 19, 2001 767-78A0088
9

### Page 12

ALERT BOEING SERVICE BULLETIN 767-78A0088 ALERT
UPPER ANGLE GEARBOX
ELECTRO−MECHANICAL BRAKE
(LEFT SIDE SHOWN,
RIGHT SIDE TURNED 180 DEGREES)
CENTER
(CDU)
DRIVE UNIT
DRIVE PAD
PLATE AND
LOCKOUT
BRAKE RELEASE
CDU MANUAL
LEVER
CENTER DRIVE UNIT
V41558
FIGURE 1. ELECTRO-MECHANICAL BRAKE, CDU MANUAL BRAKE RELEASE LEVER, LOCKOUT
PLATE AND DRIVE PAD LOCATIONS
April 19, 2001 SHEET 1 OF 1 767-78A0088
10

### Page 13

Commercial
Airplane
Group
767
Service Bulletin
Number: 767-78A0088 Evaluation FormDate: April 19, 2001
ATA System: 7800
Prepared By: Phuoc Tran
SUBJECT: EXHAUST (CF6-80C2 Engines) - Thrust Reverser - Thrust Reverser Control System - Center
Drive Unit (CDU) Cone Brake and Electro-Mechanical Brake Integrity Tests
Use this evaluation form to tell us what you think of the quality of this service bulletin. We will use the data
that you give us to improve the quality of our service bulletins.
NOTE: Please do not use this evaluation form to tell us to make changes to your manuals. To make these
changes, please use a Publication Change Request (PCR) form.
Please give us this data:
(If necessary, please use the other side. Thank you for the time you used to give us your comments.)
OPERATOR: TODAY'S DATE:
PREPARED BY: TITLE:
ORGANIZATION: TELEX CODE:
TELEPHONE NUMBER: BASE:
Please rate the quality of this service bulletin: (good) 4321 (poor)
Please rate the quality of the illustrations: (good) 4321 (poor)
Will you do the change given by this service bulletin? Yes No If not, please explain:
Is this service bulletin easy to understand? Yes No If not, please explain:
Is this service bulletin easy to use? Yes No If not, please explain:
Are the Planning Information, Material Information, and
Accomplishment Instructions accurate? Yes No If not, please explain:
Is the Manpower estimate accurate? Yes No If not, please explain:
Give the completed evaluation form to your Boeing Field Service Representative or send the evaluation form
directly to this address:
Manager
Service Bulletin Engineering
Boeing Commercial Airplane Group
P.O. Box 3707, Mail Stop 2H-37
Seattle, WA 98124-2207

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