### Commercial Airplane Group 

# 767 Service Bulletin
ALERT
Number: 767-78A0088 

## Summary 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
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

## 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

### 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

## 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

## 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

## 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

## 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

## ALERT BOEING SERVICE BULLETIN 767-78A0088 

## ALERT

BLANK PAGE

April 19, 2001 767-78A0088 6

## 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

## 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

## 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 . .. . . . . . . . . . . 10

April 19, 2001 767-78A0088 9

## 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 UNITV41558

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

### Commercial Airplane Group 

# 767 Service Bulletin

Number: 767-78A0088 

## Evaluation Form Date: 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