# CUSTOMER BULLETIN

SUBJECT

NUMBER 121

FLIGHT CONTROLS (ATA 27)

INSPECTION - FLIGHT CONTROL SURFACES PAINT THICKNESS

MARCH 23, 2012Gulfstream G550 Customer Bulletin No. 121 “March 23, 2012”

Page 1 of 8 Flight Controls (ATA 27), Inspection – Flight Control Surfaces Paint Thickness

I. Planning Information:
A. Effectivity:

Aircraft serial numbers 5038, 5079, 5223, 5227, 5237, 5240, 5245, 5246, 5252, 5258, 5261, 5265, 5267, 5283, 5290, 5293, 5294, 5302, 5307, 5311, 5318 and 5320

B. Reason:
Gulfstream has determined through routine records review that, during application, the flight control surfaces paint thickness may not have been properly documented on a number of aircraft. Excessive paint thickness will affect the balance moment of the flight control surface and may result in reduced control surface flutter margin.
C. Description:
This customer bulletin is divided into two parts:
Part I of this customer bulletin is a one-time action to inspect the flight control surface paint thickness on identified aircraft and to incorporate Airplane Flight Manual Supplement (AFMS) G550-2012-01 or EASA- G550-2012-01, as applicable, imposing altitude restrictions for any aircraft found to have excessive paint.
Part II of this customer bulletin is a one-time action to correct any excessive paint thickness conditions identified by the Part I inspection. This part will also remove the AFMS altitude restrictions upon completion of corrective action.

Note: All references in this document are intended to be inclusive of any amendments or revisions unless otherwise stated.
D. Compliance:
Compliance with Part I of this customer bulletin is required within 90 days of the release date.
Compliance with Part II of this customer bulletin, if necessary, is required within 12 months from compliance with Part I of this customer bulletin.
This customer bulletin is a managed program and should be accomplished at a Gulfstream Aerospace Authorized Warranty Repair Facility. Compliance with this customer bulletin must be coordinated through Gulfstream Scheduling at 800-810-GULF (4853), or 912-965-4178. If not scheduled, down times could increase significantly.
E. Approval:
This customer bulletin has been FAA approved as this issue is the subject of FAA Airworthiness action. It does not contain any modification information nor revise the approved configuration and as such does not require any other regulatory approval.Gulfstream G550 Customer Bulletin No. 121 “March 23, 2012”

Page 2 of 8 F. Manpower: Inspection (Part I) - 4.5 man-hours

Note: Listed man-hours are for Part I inspection only. Due to the potential variation of work requirements to correct any deficiencies, labor coverage for Part II corrective action must be charged on a separate work order and submitted for warranty consideration.

G. Material:

None

H. References:

 G550 Aircraft Maintenance Manual (AMM), Chapters 20 and 27

 G550 Airplane Flight Manual (AFM)

 G550 Airplane Flight Manual Supplement (AFMS) G550-2012-01 (attached)

 G550 Airplane Flight Manual Supplement (AFMS) EASA-G550-2012-01 (attached)

 Gulfstream Aerospace Material Process Specification (GAMPS) 4000, revision F I. Tooling/Equipment: Ultrasonic Coating Thickness Gage, Positector 200 series or equivalent J. Opportunity for No-Charge Compliance: Labor and material will be provided at no charge if this customer bulletin is accomplished within the recommended compliance time, as stated in this document, at a Gulfstream G550 Authorized Warranty Repair Facility.

Note: Additional labor hours incurred due to aircraft configuration or mechanical difficulties must be charged on a separate work order and submitted for warranty consideration.

Note: Labor and materials for corrective action (Part II), if necessary, must be charged on a separate work order and submitted for warranty consideration. K. Weight and Balance:
N/A



### Part I
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 NECESSA RY TO VERIFY ABSENCE OF ANY DEBRIS PRIOR TO COMPLETION OF PROCEDURE. FAILURE TO COMPLY MAY RESULT IN DAMAGE TO COMPONENTS AND / OR SYSTEMS.Gulfstream G550 Customer Bulletin No. 121 “March 23, 2012”

Page 3 of 8 A. Prepare the aircraft for safe maintenance. Refer to AMM, Safe Ground Maintenance Procedure, Chapter 20

.
B. Gain access to all flight control su rfaces (aileron, rudder and elevator).

C. Using the paint thickness measurement maps (Tables 1, 2 and 3) mark the reading points on both sides of each flight control surface.

D. Using an ultrasonic coating thickness gage, Positector 200 series or equivalent, measure the paint thickness on the flight control surfaces at each reading point as shown on the paint thickness measurement map for each respective flight control surface. Record readings on the appropriate tables. See Tables 1, 2 and 3.

E. Calculate the average paint thickness for each surface by adding all of the readings for that surface and dividing by the number of readings. For example, in Table 1 the left aileron point readings for mid-chord and rear, upper and lower surfaces would be totaled and then divided by 24, which is the number of reading points.

F. Table 4 contains maximum allowable paint thickness averages for individual aircraft serial numbers. These thickness allowances have been determined using historical balance information for each individual flight control surface to determine maximum paint thickness that could be applied without negatively affecting the balance moment, and are not required paint thicknesses. Confirm part number and serial number of the respective flight control surface prior to using the values on this chart. If the part number and/or serial number do not match the chart information, default values of 5.0 mils must be used.

G. Compare average paint thickness recorded on Tables 1, 2 and 3 with the maximum allowable paint thickness average for each flight control surface shown in Table 4. For each flight control surface perform the following:
1. If average paint thickness is equal to or less than 5.0 mils – no further action is required, proceed to Step II.H. Report Part II of this customer bulletin as “Not Applicable – No action required from Part I.”
2. If average paint thickness is greater than 5.0 mils, but equal to or less than the serial number specific allowances provided in Table 4 - no further action is required, proceed to Step II.H. Report Part II of this customer bulletin as “Not Applicable – No action required from Part I.”
3. If average paint thickness is greater than the serial number specific allowances provided in Table 4, but less than 13 mils – incorporate AFMS G550-2012-01 or EASA-G550-2012-01, as applicable, into the Airplane Flight Manual for continued operation at or below 45,000 feet until condition is corrected. Compliance with Part II of this customer bulletin is required within 12 months from compliance with Part I.
4. If average paint thickness is greater than the serial number specific allowances provided in Table 4, and exceeds 13.0 mils – continued operation is not allowed, contact Gulfstream Customer Support for instructions on compliance with Part II of this customer bulletin.

H. Ensure work area is clean and clear of foreign objects (FOD).Gulfstream G550 Customer Bulletin No. 121 “March 23, 2012”

Page 4 of 8 I. Record compliance with Part I of this customer bulletin in the aircraft’s permanent maintenance records and return aircraft to flight status.

J. Report compliance with Part I of this customer bulletin to Gulfstream Computerized Maintenance Program (CMP) via electronic transmittal or fill out and fax the attached service reply card.



### Part II

III. 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 NECESSA RY TO VERIFY ABSENCE OF ANY DEBRIS PRIOR TO COMPLETION OF PROCEDURE. FAILURE TO COMPLY MAY RESULT IN DAMAGE TO COMPONENTS AND / OR SYSTEMS.

A. Prepare the aircraft for safe maintenance. Refer to AMM, Safe Ground Maintenance Procedure, Chapter 20

.
B. For affected surfaces having an overall average thickness greater than the values shown on Table 4 as described in Part I, Steps II.G.3. and II.G.4., one of the following corrective actions shall be required within the specified compliance time. Contact Gulfstream Customer Support for assistance in determining the appropriate corrective action.
1. Remove flight control surface and rebalance per AMM, Chapter 27.
2. Strip and repaint with average thickness less than 5.0 mils. Re-measure thickness. Refer to GAMPS 4000, revision F.

3. Sand/buff down to 5.0 mils or less and re-measure thicknesses (not recommended on surfaces with averages exceeding 7.0 mils). Refer to GAMPS 4000, revision F.

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

D. Remove Airplane Flight Manual Supplement G550-2012-01 or EASA-G550-2012-01, as applicable, from the Airplane Flight Manual.

E. Record compliance with Part II of this customer bulletin in the aircraft’s permanent maintenance records and return aircraft to flight status.

F. Report compliance with Part II of this customer bulletin to Gulfstream Computerized Maintenance Program (CMP) via electronic transmittal or fill out and fax the attached service reply card.
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 G550 Customer Bulletin No. 121 “March 23, 2012”

Page 5 of 8Gulfstream G550 Customer Bulletin No. 121 “March 23, 2012”

Page 6 of 8Gulfstream G550 Customer Bulletin No. 121 “March 23, 2012”

Page 7 of 8Gulfstream G550 Customer Bulletin No. 121 “March 23, 2012”

Page 8 of 8Gulfstream G550 Customer Bulletin No. 121 “March 23, 2012”

Customer Bulletin prepared by Gulfstream Aerospace, 500 Gulfstream Road, P.O. Box 2206, Savannah, Georgia 31402-2206, USA.
© 2012 Gulfstream Aerospace All rights reserved, including the right to reproduce this pub lication. No part may be reproduced, stored in any retrieval syst em, or transmitted in any part or form or by any means, electronic, photocopying, micr ofilm, microfiche, mechanical, or otherwise, without prior written permission of Gu lfstream Aerospace.

This technical data is controlled under the Ex port Administration Regulations by General License TSU. It may not be transferre d 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 fax this page to Gulfstream CMP at 800-944-1775 or 912-963-0265.
The following Customer Bulletin (CB) has been addressed:

CB Number A/C A/C Type Compliance Date

981210 G550

Aircraft Hours Aircraft Landings

This Customer Bulletin is not applicable because:

Serial Number not affected Appliance not installed ______Previously complied with (annotate method of compliance below)

Signature Title/Certificate Number Company

Comments / Suggestions:Gulfstream G550 Customer Bulletin No. 121 “March 23, 2012”

Customer Bulletin prepared by Gulfstream Aerospace, 500 Gulfstream Road, P.O. Box 2206, Savannah, Georgia 31402-2206, USA.
© 2012 Gulfstream Aerospace All rights reserved, including the right to reproduce this pub lication. No part may be reproduced, stored in any retrieval syst em, or transmitted in any part or form or by any means, electronic, photocopying, micr ofilm, microfiche, mechanical, or otherwise, without prior written permission of Gu lfstream Aerospace.

This technical data is controlled under the Ex port Administration Regulations by General License TSU. It may not be transferre d 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 fax this page to Gulfstream CMP at 800-944-1775 or 912-963-0265.
The following Customer Bulletin (CB) has been addressed:

CB Number A/C A/C Type Compliance Date

981211 G550

Aircraft Hours Aircraft Landings

This Customer Bulletin is not applicable because:

Serial Number not affected No action required from Part I ______Previously complied with (annotate method of compliance below)

Signature Title/Certificate Number Company

Comments / Suggestions:This page intentionally left blank.

### GULFSTREAM AEROSPACE G550 AIRPLANE FLIGHT MANUAL SUPPLEMENT NO. G550-2012-01

FAA APPROVED BASIC ISSUE 13 March 2012 Page 1 Introduction Gulfstream has determined that, durin g application, the flight control surfaces paint thickness was not properly documented on a number of aircraft. Excessive paint th ickness will affect the balance moment of the flight control surface and may result in reduced control surface flutter margin. The purpose of this Airplane Flight Manual Supplement is to allow temporary continued operation for non -conforming surfaces. It imposes a 6000 ft altitude ceiling reduction to allow for continued flight of aircraft with surfaces inspected and found having excess coatings.

Section 0: PREFACE No Change

Section 1: LIMITATIONS
Under 01-03-30: Maximum Operating Altitude, add CB limitation, note, and altitude envelope: Altitude Operating Restriction for Continued Flight of Aircraft with Non-Conforming Coatings:
Continued operation within CB compliance time and altitude restriction of 45,000 ft.

### GULFSTREAM AEROSPACE G550 AIRPLANE FLIGHT MANUAL SUPPLEMENT NO. G550-2012-01

BASIC ISSUE FAA APPROVED Page 2 13 March 2012 NOTE: Airplanes having flight control surfaces inspected and found to have excessive paint thickness will have a maximum operating altitude of 45,000 ft.

Figure 1. Altitude / Mach Flight Envelope

### GULFSTREAM AEROSPACE G550 AIRPLANE FLIGHT MANUAL SUPPLEMENT NO. G550-2012-01

FAA APPROVED BASIC ISSUE 13 March 2012 Page 3 Section 2: NORMAL PROCEDURES No Change

Section 3: ABNORMAL PROCEDURES No Change

Section 4: EMERGENCY PROCEDURES No Change

Section 5: PERFORMANCE No ChangeBASIC ISSUE FAA APPROVED Page 4 13 March 2012 This page intentionally left blank.This page intentionally left blank.

### GULFSTREAM AEROSPACE G550 EASA AIRPLANE FLIGHT MANUAL SUPPLEMENT NO. EASA-G550-2012-01

FAA APPROVED BASIC ISSUE 14 March 2012 Page 1 Introduction Gulfstream has determined that, durin g application, the flight control surfaces paint thickness was not properly documented on a number of aircraft. Excessive paint th ickness will affect the balance moment of the flight control surface and may result in reduced control surface flutter margin. The purpose of this Airplane Flight Manual Supplement is to allow temporary continued operation for non -conforming surfaces. It imposes a 6000 ft altitude ceiling reduction to allow for continued flight of aircraft with surfaces inspected and found having excess coatings.

Section 0: PREFACE No Change

Section 1: LIMITATIONS
Under 01-03-30: Maximum Operating Altitude, add CB limitation, note, and altitude envelope: Altitude Operating Restriction for Continued Flight of Aircraft with Non-Conforming Coatings:
Continued operation within CB compliance time and altitude restriction of 45,000 ft.

### GULFSTREAM AEROSPACE G550 EASA AIRPLANE FLIGHT MANUAL SUPPLEMENT NO. EASA-G550-2012-01

BASIC ISSUE FAA APPROVED Page 2 14 March 2012 NOTE: Airplanes having flight control surfaces inspected and found to have excessive paint thickness will have a maximum operating altitude of 45,000 ft.

Figure 1. Altitude / Mach Flight Envelope

### GULFSTREAM AEROSPACE G550 EASA AIRPLANE FLIGHT MANUAL SUPPLEMENT NO. EASA-G550-2012-01

FAA APPROVED BASIC ISSUE 14 March 2012 Page 3 Section 2: NORMAL PROCEDURES No Change

Section 3: ABNORMAL PROCEDURES No Change

Section 4: EMERGENCY PROCEDURES No Change

Section 5: PERFORMANCE No ChangeBASIC ISSUE FAA APPROVED Page 4 14 March 2012 This page intentionally left blank.