TRANSMITTAL SHEET 

November 13, 2015 Transmittal 

 Page 1 

This sheet transmits Revision A, dated November 13, 2015, to Gulfstream G650 Alert Customer 

Bulletin (ACB) 4, dated November 6, 2015, titled Landing Gear (ATA 32), Inspection – Brake Inlet 

Self-Sealing Couplings Torque. 

Reason for Revision: 

After regulatory review of ACB No. 4, the Federal Aviation Administration (FAA) has requested a 

revised coupling re-torque procedure to loosen the coupling and record the break-away torque 

prior to torquing the coupling. Procedures are clarified to more accurately explain the torquing 

procedure and conform to recent changes to the Aircraft Maintenance Manual (AMM). The FAA 

has agreed that operators who have previously complied with ACB No. 4 are not required to 

perform the re-torque again. In addition, a follow-on re-torque of the brake fittings is required after 

completion of 100 landing cycles following the initial re-torque. 

I. Planning Information: 

Step I.A. Effectivity: Effectivity has been revised. 

Step I.C. Safety Intent: Information has been added concerning cockpit indications and 

upcoming Gulfstream action. 

Step I.D. Description: This bulletin has been divided into two parts with a follow-on 

requirement to repeat the inspection after 100 landing cyles. 

Step I.E. Compliance: Compliance has been included for Part II of this bulletin. 

Step I.F. Approval: Approval statement rewording to reflect FAA pending action. 

Step I.G. Manpower: Labor hour added for compliance with Part II. 

Step I.J. Tooling: Dial indicating torque wrench has been added to facilitate 

measurement of break-away torque. 

II. Accomplishment Instructions: 

Moved “RC” compliance note to beginning of section 

Step II.C. Added step to measure and record break-away torque while loosening selfsealing coupling. Revised instructions on loosening procedure 

Step II.D. Revised instructions to conform to recent AMM revision 

III. Accomplishment Instructions: Added Part II 

Figure 1 Revised brake fitting nomenclature to conform to recent AMM revision. 

Effect of Revision on Prior Accomplishment:

This customer bulletin revision replaces ACB 4, dated November 6, 2015. Aircraft operators who 

have previously complied with ACB 4, dated November 6, 2015, are in compliance with Part I of 

this revision and should return the Part I service reply card marked “Previously complied with.” 

Part II must be performed following completion of 100 landing cycles after compliance with ACB 4, 

dated November 6, 2015, or Part I of this bulletin. 
TRANSMITTAL SHEET 

November 13, 2015 Transmittal 

 Page 2 

Note: This customer bulletin has been reproduced in its entirety. A black bar in the left margin 

indicates a change in that line of text or figure. 

List of Effective Pages: 

Page No. Date 

1 - 5 November 13, 2015 

 

Revision History: 

Original Issue: November 6, 2015 

Revision A: November 13, 2015
ALERT 

NUMBER 4A 

LANDING GEAR (ATA 32) 

INSPECTION – BRAKE INLET SELF-SEALING 

COUPLINGS TORQUE 

NOVEMBER 13, 2015 
Gulfstream G650 Alert Customer Bulletin No. 4A 

“November 13, 2015” 

Page 1 of 5 

Landing Gear (ATA 32), Inspection – Brake Inlet Self-Sealing Couplings Torque 

I. Planning Information: 

A. Effectivity: 

Aircraft serial numbers 6001, 6003 through 6163 

Affected aircraft that have previously complied with Alert Customer Bulletin No. 4, dated 

November 6, 2015, titled Landing Gear (ATA 32), Inspection – Brake Inlet Self-Sealing 

Couplings Torque, are only affected by Part II of this bulletin. 

B. Reason: 

Self-sealing couplings on the brake inlet fitting have been found backed out of the fully 

seated position. Due to the function of these couplings, this condition can allow the selfsealing mechanism to activate and cut off hydraulic pressure to the brake caliper, 

resulting in no braking on the affected wheel while brake pressure indications remain 

normal on cockpit indications. 

C. Safety Intent: 

Inadequate torque on the self-sealing coupling may allow it to back off over time, 

actuating the self-sealing function. This will result in loss of hydraulic pressure to the 

affected brake, disabling braking action and de-spin function. Multiple coupling failures 

may lead to loss of braking capability on more than one wheel creating potential for 

reduced aircraft braking effectiveness. Since cockpit brake pressure indications are 

normal, the crew will have no indications prior to take-off, followed by an amber wheel 

de-spin Crew Alerting System (CAS) message after gear retraction. Gulfstream will be 

issuing a Quick Reference Handbook (QRH) revision to provide flight crews with 

updated procedures intended to mitigate a wheel de-spin CAS message until a design 

change can be implemented. 

D. Description: 

This customer bulletin is divided into two parts. Part 1 is a one-time action to perform a 

breakaway check and re-torque of the brake inlet self-sealing couplings on affected 

aircraft. Part II is a repetition of the Part I inspection to be performed 100 landing cycles 

after compliance with either the original issue of ACB No. 4, dated November 6, 2015, or 

Part I of this bulletin. 

E. Compliance: 

Compliance with Part I of this customer bulletin is required within 30 days from the 

original issue date of November 6, 2015, for aircraft that have not previously complied 

with Alert Customer Bulletin No. 4, issue date as stated. 

Compliance with Part II of this customer bulletin is required at the completion of 100 

landing cycles following compliance with either the original issue of ACB No. 4, dated 

November 6, 2015, or Part I of this bulletin. 

F. Approval: 

This customer bulletin has been reviewed and approved by the Federal Aviation 

Administration and is the subject of pending Airworthiness Directive regulatory action. 
Gulfstream G650 Alert Customer Bulletin No. 4A 

“November 13, 2015” 

Page 2 of 5 

G. Manpower: 

Part I Inspection - 2 labor hours 

Part II Inspection - 2 labor hours 

NOTE: Labor hours may vary due to aircraft configuration or mechanical difficulty. 

H. Material: 

None 

I. References: 

G650 Aircraft Maintenance Manual (AMM), Chapters 20 and 32 

NOTE: All references in this document are intended to be inclusive of any amendments 

or revisions unless otherwise stated. 

J. Tooling/Equipment: 

 Standard aircraft maintenance tools 

 Torque wrench, dial indicating, 0 – 300 inch-pounds GSE5101082 or equivalent. 

 Torque wrench, 200 – 1000 inch-pounds, GSE5100722 or equivalent 

K. Warranty Coverage – Component:

Labor and material will be at no charge if the aircraft is within the component warranty 

period as of the original issue date of this customer bulletin and work is accomplished 

within the recommended compliance time, as stated in this document, at a Gulfstream 

G650 Authorized Warranty Facility or Factory Authorized Service Center.* 

*Coverage is granted per the terms and conditions of the Gulfstream Aircraft Sales 

Agreement to the original purchaser or subsequent owner with appropriate Assignment 

of Warranties on file with Gulfstream. 

NOTE: Additional labor hours incurred due to aircraft configuration or mechanical 

difficulties must be charged as a separate discrepancy and submitted for 

warranty consideration. 

L. Weight and Balance: 

N/A 
Gulfstream G650 Alert Customer Bulletin No. 4A 

“November 13, 2015” 

Page 3 of 5 

II. Part I Accomplishment Instructions: 

CAUTION: PROTECT WIRE BUNDLES, CONNECTORS AND SURROUNDING 

STRUCTURE DURING ANY MAINTENANCE PROCEDURE FROM SHAVINGS, 

DEBRIS AND CONTAMINATION. MAINTAIN A PROPERLY CLEANED WORK 

AREA THROUGHOUT THE PROCEDURE TO ENSURE THE INTEGRITY OF 

THE AFFECTED COMPONENT / SYSTEM. VISUALLY INSPECT WORK AREA 

USING ADDITIONAL LIGHT AS NECESSARY TO VERIFY ABSENCE OF ANY 

DEBRIS PRIOR TO COMPLETION OF PROCEDURE. FAILURE TO COMPLY 

MAY RESULT IN DAMAGE TO COMPONENTS AND / OR SYSTEMS. 

NOTE: Some steps in the accomplishment instructions are identified as Required for 

Compliance (RC). If this CB is mandated by an airworthiness directive (AD), the 

steps identified as RC must be done to comply with the AD. Steps not identified 

with RC are recommended and may be deviated from, done as part of other 

actions, or done with accepted methods different from those given in the CB, if the 

RC steps can be done and the aircraft can be put back in service in a serviceable 

condition. 

A. Prepare the aircraft for safe maintenance. Refer to AMM, Safe Ground Maintenance 

Procedure, Chapter 20. 

WARNING: FAILURE TO INSTALL ALL LANDING GEAR AND LANDING GEAR DOOR 

SAFETY DEVICES BEFORE WORKING IN ANY WHEEL WELL MAY RESULT 

IN SERIOUS INJURY OR DEATH. 

B. Gain access to the brake assemblies located on the main landing gear. See Figure 1. 

C. RC – Using torque wrench, GSE5101082 or equivalent, loosen the self-sealing coupling 

from each brake caliper reducer fitting. Measure the breakaway torque and record it on 

the service reply card.

NOTE: Backup wrench is required to prevent loosening of the reducer fitting. 

NOTE: Do not loosen the coupling enough to allow the fitting to leak, this will allow air 

into the system, requiring bleeding of the affected brake caliper. Loosen only 

until the torque wrench reads a stable value at or near 0 inch-pounds. 

D. RC - Using torque wrench, GSE5100722 or equivalent, torque the self-sealing couplings 

on the brake caliper fitting to 215 – 285 inch-pounds at all four brake calipers. See 

Figure 1, Detail A. Torque the coupling flat closest to the caliper fitting. Backup wrench is 

required to prevent overtorquing of the reducer fitting during torque application. 

E. Ensure work area is clean and clear of foreign objects (FOD). 

F. Record compliance with this customer bulletin in the aircraft’s permanent maintenance 

records and return aircraft to flight status. 

G. Report compliance with this customer bulletin to Gulfstream Computerized Maintenance 

Program (CMP) by uploading the attached service reply card, along with the CMP task 

card(s) sign-off using MyGulfstream, MyCMP Document Upload or e-mail to 

cmp.docproc@gulfstream.com or fax to Gulfstream CMP at 800-944-1775 or 912-963-0265. 

If technical assistance is required, contact your area Gulfstream Field Service Representative or call 

Gulfstream Customer Support at 800-810-GULF (4853) or 912-965-4178 (fax 912-965-4184). 
Gulfstream G650 Alert Customer Bulletin No. 4A 

“November 13, 2015” 

Page 4 of 5 

III. Part II Accomplishment Instructions: 

CAUTION: PROTECT WIRE BUNDLES, CONNECTORS AND SURROUNDING 

STRUCTURE DURING ANY MAINTENANCE PROCEDURE FROM SHAVINGS, 

DEBRIS AND CONTAMINATION. MAINTAIN A PROPERLY CLEANED WORK 

AREA THROUGHOUT THE PROCEDURE TO ENSURE THE INTEGRITY OF 

THE AFFECTED COMPONENT / SYSTEM. VISUALLY INSPECT WORK AREA 

USING ADDITIONAL LIGHT AS NECESSARY TO VERIFY ABSENCE OF ANY 

DEBRIS PRIOR TO COMPLETION OF PROCEDURE. FAILURE TO COMPLY 

MAY RESULT IN DAMAGE TO COMPONENTS AND / OR SYSTEMS. 

NOTE: Some steps in the accomplishment instructions are identified as Required for 

Compliance (RC). If this CB is mandated by an airworthiness directive (AD), the 

steps identified as RC must be done to comply with the AD. Steps not identified 

with RC are recommended and may be deviated from, done as part of other 

actions, or done with accepted methods different from those given in the CB, if the 

RC steps can be done and the aircraft can be put back in service in a serviceable 

condition. 

A. Prepare the aircraft for safe maintenance. Refer to AMM, Safe Ground Maintenance 

Procedure, Chapter 20. 

WARNING: FAILURE TO INSTALL ALL LANDING GEAR AND LANDING GEAR DOOR 

SAFETY DEVICES BEFORE WORKING IN ANY WHEEL WELL MAY RESULT 

IN SERIOUS INJURY OR DEATH. 

B. Gain access to the brake assemblies located on the main landing gear. See Figure 1. 

C. RC – Using torque wrench, GSE5101082 or equivalent, loosen the self-sealing coupling 

from each brake caliper reducer fitting. Measure the breakaway torque and record it on 

the service reply card.

NOTE: Backup wrench is required to prevent loosening of the reducer fitting. 

NOTE: Do not loosen the coupling enough to allow the fitting to leak, this will allow air 

into the system, requiring bleeding of the affected brake caliper. Loosen only 

until the torque wrench reads a stable value at or near 0 inch-pounds. 

D. RC - Using torque wrench, GSE5100722 or equivalent, torque the self-sealing couplings 

on the brake caliper fitting to 215 – 285 inch-pounds at all four brake calipers. See 

Figure 1, Detail A. Torque the coupling flat closest to the caliper fitting. Backup wrench is 

required to prevent overtorquing of the reducer fitting during torque application. 

E. Ensure work area is clean and clear of foreign objects (FOD). 

F. Record compliance with this customer bulletin in the aircraft’s permanent maintenance 

records and return aircraft to flight status. 

G. Report compliance with this customer bulletin to Gulfstream Computerized Maintenance 

Program (CMP) by uploading the attached service reply card, along with the CMP task 

card(s) sign-off using MyGulfstream, MyCMP Document Upload or e-mail to 

cmp.docproc@gulfstream.com or fax to Gulfstream CMP at 800-944-1775 or 912-963-0265. 

If technical assistance is required, contact your area Gulfstream Field Service Representative or call 

Gulfstream Customer Support at 800-810-GULF (4853) or 912-965-4178 (fax 912-965-4184). 
Gulfstream G650 Alert Customer Bulletin No. 4A 

“November 13, 2015” 

Page 5 of 5 

Brake Assembly (Typical) 

Figure 1
Gulfstream G650 Alert Customer Bulletin No. 4A 

“November 13, 2015” 

Customer Bulletin prepared by Gulfstream Aerospace, 500 Gulfstream Road, P.O. Box 2206, Savannah, Georgia 31402-2206, USA. 

© 2015 Gulfstream Aerospace 

All rights reserved, including the right to reproduce this publication. No part may be reproduced, stored in any retrieval system, or transmitted in any part or form or 

by any means, electronic, photocopying, microfilm, microfiche, mechanical, or otherwise, without prior written permission of Gulfstream Aerospace. 

This technical data is controlled under the Export Administration Regulations by General License TSU. It may not be transferred to a third party 

without the prior written approval of the U.S. Department of Commerce.

GA 611A 2/97 

Part I 

Service Reply Card 

Please upload this page, along with the CMP task card(s) sign-off using MyGulfstream, MyCMP 

Document Upload, or e-mail to cmp.docproc@gulfstream.com or fax to Gulfstream CMP at 800-

944-1775 or 912-963-0265. 

The following Alert Customer Bulletin (ACB) has been addressed: 

CB Number A/C A/C Type Compliance Date 

990041 G650 

Aircraft Hours 

Aircraft Landings 

This Customer Bulletin is not applicable because: 

 Serial Number not affected 

 Equipment not installed 

______Previously complied with (annotate method of compliance below) 

______Other (explain reason below) 

Record Breakaway Torque: 

Left Outboard (#1) Left Inboard (#2) Right Inboard (#3) Right Outboard (#4) 

 

 

 

Signature Title/Certificate Number Company 

Comments / Suggestions: 
Gulfstream G650 Alert Customer Bulletin No. 4A 

“November 13, 2015” 

Customer Bulletin prepared by Gulfstream Aerospace, 500 Gulfstream Road, P.O. Box 2206, Savannah, Georgia 31402-2206, USA. 

© 2015 Gulfstream Aerospace 

All rights reserved, including the right to reproduce this publication. No part may be reproduced, stored in any retrieval system, or transmitted in any part or form or 

by any means, electronic, photocopying, microfilm, microfiche, mechanical, or otherwise, without prior written permission of Gulfstream Aerospace. 

This technical data is controlled under the Export Administration Regulations by General License TSU. It may not be transferred to a third party 

without the prior written approval of the U.S. Department of Commerce.

GA 611A 2/97 

Part II 

Service Reply Card 

Please upload this page, along with the CMP task card(s) sign-off using MyGulfstream, MyCMP 

Document Upload, or e-mail to cmp.docproc@gulfstream.com or fax to Gulfstream CMP at 800-

944-1775 or 912-963-0265. 

The following Alert Customer Bulletin (ACB) has been addressed: 

CB Number A/C A/C Type Compliance Date 

990042 G650 

Aircraft Hours 

Aircraft Landings 

This Customer Bulletin is not applicable because: 

 Serial Number not affected 

 Equipment not installed 

______Previously complied with (annotate method of compliance below) 

______Other (explain reason below) 

Record Breakaway Torque: 

Left Outboard (#1) Left Inboard (#2) Right Inboard (#3) Right Outboard (#4) 

 

 

 

Signature Title/Certificate Number Company 

Comments / Suggestions: