Part of GE’s Aviat ion Business

 SERVICE BULLETIN .

SERVICE BULLETIN

SERVICE BULLETIN 61-1043

TRANSMITTAL LETTER FOR REVISION NO. 5

Dated Oct 15/10

1. REASON

A. Update the service bulletin classification to ALERT.

B. Provide new compliance instructions.

C. Amend references and contact details.

D. Add new Appendix B Status Report.

E. Reformat the service bulletin and appendices.

2. ACTION

A. Remove and destroy existing pages 1 to 5 of the service bulletin and insert revised pages 1 to 4 dated 

Oct 15/10.

B. Remove and destroy existing pages 1 to 3 of Appendix A and insert revised pages 1 to 3 dated Oct 15/10.

C. Insert new Appendix B page 1 dated Oct 15/10.

Dowty Propellers

Anson Business Park, Cheltenham Road East, Gloucester, GL2 9QN ENGLAND

Telephone: 01452 716000 Facsimile: 01452 716001

Page 1 of 4

CAGE CODE: U7387

For Europe, Africa, India and

Middle East contact:

Dowty Propellers

Anson Business Park

Cheltenham Road East,

Gloucester, GL2 9QN, United Kingdom

T: + 44 (0)1452 716000

F: + 44 (0)1452 716001

For Asia, Australasia and the Pacific

contact:

Dowty Propellers

Anson Business Park

Cheltenham Road East,

Gloucester, GL2 9QN, United Kingdom

T: + 44 (0)1452 716000

F: + 44 (0)1452 716001

For the Americas

contact:

Dowty Propellers

114 Powers Court

Sterling, VA 20166

United States of America

T: + 1 (703) 421 4434

F: + 1 (703) 450 0087

Copyright (2010), GE Aviation Systems Ltd., U.K

The information contained in this document is GE Aviation Systems Ltd proprietary information and is disclosed in confidence. It is the

property of GE Aviation Systems Ltd and shall not be used, disclosed to others or reproduced without the express written consent of GE

Aviation Systems Ltd, including, but without limitation, it is not to be used in the creation, manufacture, development, or derivation of any

repairs, modifications, spare parts, designs, or configuration changes or to obtain FAA, CAA, EASA, or any other government or 

regulatory approval to do so. If consent is given for reproduction in whole or in part, this notice and the notice set forth on each page of

this document shall appear in any such reproduction in whole or in part.

All technical documentation and information contained herein, with respect to assembly and disassembly, cleaning, inspection methods

and limits, repair methods and limits, operational limits, life limits and the like, have been developed and approved for use with this

equipment and parts that have been manufactured and/or approved by GE and that have been maintained in accordance with GE 

technical documentation and recommendations. GE has no contractual or legal obligation for, nor knowlege of, non-GE-approved parts

and repairs. Accordingly, this document is not intended to apply to non-GE-approved parts and repairs.

ALERT

Manual Ref: See para H.

SERVICE BULLETIN

PROPELLER - PROPELLER HUBS - INSPECTION OF THE BUTTRESS THREADS IN HUB PORTS FOR 

CRACKS

1. Planning Information

WARNING: FAILURE TO IMPLEMENT ANY INSTRUCTION GIVEN HERE, AS AMENDED FROM TIME TO

TIME BY DOWTY PROPELLERS, MAY ENDANGER HEALTH AND SAFETY.

A. Effectivity

Aircraft affected : HS748 Aircraft

Units affected : Propeller

(1) HS748, R212/4-30-4/22:

(a) Hub and Driving Centre Assembly, Part No. RA64883

(2) HS748, R251/4-30-4/49:

(a) Hub and Driving Centre Assembly, Part No. 601022105 and 601022211

B. Reason

(1) A small number of hubs which have accumulated in excess of 6000 flying hours and from a a small

number of operators, have been found to be cracked in the hub port buttress threads.

Non Mod

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C. Description

(1) This service bulletin is applicable to all operators. An NDT inspection of hubs for cracks in the area

of the buttress threads in accordance with Dowty Popellers NDT technique NDT 175U. Refer to

Appendix A to this service bulletin.

NOTE : Hub buttress threads are currently examined for cracks in accordance with Dowty

Popellers NDT technique NDT 21/M (Reference Dowty Propellers Standard Practices

Manual 60-00-00) at every overhaul.

D. Compliance

(1) ALERT

(a) The buttress threads of all propeller hubs must be inspected for cracks at overhaul, using

NDT technique NDT 175U.

(b) For operators who have discovered a crack in the buttress thread of any propeller hub within

their fleet:

1 Do an inspection to NDT 175U (Appendix A) within 500 flying hours of the issue of

Revision 5 of this service bulletin. 

2 Following the satisfactory completion of these inspections, hubs must be inspected after

every 500 flying hours.

3 NDT 175U (Appendix A) applies to in-service inspections. NTD 21-M applies to

inspections at overhaul.

(c) For operators who have no history of cracks in the buttress thread of any propeller hub within

their fleet:

1 Do an inspection of all hubs that have exceeded 8000 flying hours to NDT 175U

(Appendix A) within 1200 of the issue of Revision 5 of this service bulletin.

2 Following the satisfactory completion of these inspections, hubs must be inspected after

every 1200 flying hours.

E. Approval

(1) This service bulletin was approved and classified as ALERT. The technical content of this service

bulletin, which affects airworthiness, is approved under Design Organisation Approval No.

EASA.21J.008. This service bulletin is expected to be the subject of an EASA Airworthiness

Directive.

F. Manpower

(1) This inspection will take approximately 1 manhour, plus time to gain access.

G. Material

(1) New parts may be required dependant on the result of the crack test. For part numbers refer to

Overhaul Manual 61-10-1.

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H. Tooling

(1) Crack testing equipment as detailed in NDT Technique No. NDT 175U (Appendix A to this bulletin).

I. Weight and Balance

(1) None.

J. References

(1) Dowty Propellers Maintenance Manual, Publication No. 905.

(2) Dowty Propellers Overhaul Manual, 61-10-1.

(3) Dowty Propellers Standard Practices Manual 60-00-00.

(4) Aircraft Maintenance Manual.

K. Other Publications Affected

(1) None.

2. Accomplishment Instructions

For all candidate propellers and propeller equipment Dowty Propellers, or an approved maintenance

organisation working in consultation with Dowty Propellers, must do the following:

A. Procedure

(1) Remove the propeller spinner in accordance with the instructions in the aircraft maintenance

manual.

(2) Function the propeller to fully feather the propeller blades.

(3) Crack test the propeller hub buttress threads in accordance with Dowty Propellers NDT technique

NDT 175U as detailed in Appendix A to this service bulletin.

(4) If no cracks are found: 

(a) Refit the propeller spinner and return the aircraft to service.

(b) Write the details of the satisfactory propeller hub inspection on a copy of the status report. 

Refer to Appendix B. Send the status report to the the Product Support Manager at the

address given in para. (5) (e).

(5) If the hub is found to be cracked:

(a) Show the position of the crack in the buttress thread and the extent of the crack around the

hub blade port on a copy of the status report. Refer to Appendix B.

(b) Remove the propeller from the aircraft in accordance with the maintenance manual.

(c) Disassemble the propeller and, using a serviceable hub and driving centre assembly,

completely reassemble in accordance with the overhaul manual requirements, including

testing, re-balancing and re-setting angles.

(d) Re-install the propeller on the aircraft in accordance with the maintenance manual.

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(e) Send the details on the status report (Appendix B) immediately to:

The Product Support Manager,

Dowty Propellers,

Anson Business Park,

Cheltenham Road,

Gloucester,

Gl2 9QN

United Kingdom.

Email: Kerry.Garfield@ge.com

Tel: +44 (0) 1452 716000, Fax +44 (0) 1452 716001

(f) Return the cracked hub and driving centre assembly to Dowty Propellers marked for the

attention of the Product Support Manager at the address given above. Attach a label to the

hub and driving centre assembly giving the following information:

1 Propeller serial number and time since new (TSN).

2 Hub part number and serial number where different from propeller serial number.

3 Position and extent of cracks.

4 Hub time since overhaul (TSO).

5 Other data relating to impact damage, reworking, salvage, etc.

B. Recording Instructions

(1) Record compliance with this inspection as SB 61-1043 in the hub assembly history card and the

propeller log book.

(2) Record in the appropriate aircraft documentation the aircraft flying hours at which the inspection is

to be repeated.

3. Material Information

A. Not applicable.

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ALERT

APPENDIX A

NDT TECHNIQUE N0. NDT 175U

THE ULTRASONIC INSPECTION OF THE HS748 PROPELLER HUB PORT BUTTRESS THREADS

1. Introduction

A. This technique is designed for the detection of fatigue cracking originating from the root of the buttress 

thread in blade ports.

2. Equipment Required

A. Ultrasonic flaw detector operating in the 1 to 10 Mhz range.

B. A suitable 10Mhz compressional wave probe. The following are recommended as suitable:

(1) Harrisonic GR1004, fitted with a 0.50 in. (12,7 mm) delay line.

(2) Krautkramer Aerotech DFR 126-660, fitted with a 0.50 in. (12,7 mm) delay line.

(3) Nortec Probe No. 14878 (Y-M-1/8-10).

C. Grease to be used on couplant.

D. Calibration block Dowty Propellers no. SE.8372 obtainable from Dowty Propellers.

E. Forceps approximately 7.88 in. (200 mm) in length.

NOTE : The above are required to hold the wave probe when inspecting to the rear of the hub ports.

3. Calibration Procedure.

A. Place the probe on the calibration block no. SE.8372 above an area of full thread.

B. Tilt the probe outwards away from the thread and identify the thread form signals. Adjust the timebase to 

place the inner last thread signal at 8 on the timebase.

C. Place the probe on the calibration block above the centre of the calibration slot.

D. Tilt the probe slowly outwards and inwards, the signal from the slot will rise as the thread form signal 

disappears.

E. Move the probe to maximise signal from the slot. Set the signal to 80% full screen.

F. Fill the blade bearing nut castellations with grease.

G. Position the probe on hub port abutting inner face of castellation. See Figure 1.

H. Tilt the probe slowly outwards until the thread form signals are displayed on the screen. Note the number 

of threads. There should be a minimum of 6 threads displayed, see para. (M) below.

I. Tilt the probe slowly back to vertical until the thread form signals disappear.

J. The crack signal will rise as the thread form signal disappears.

K. To confirm a crack slowly tilt the probe in and out, the crack signal will increase as the thread form signal 

decreases and vice versa.

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ALERT

L. Repeat paras. F to J for each castellation.

NOTE : Hold the probe with the forceps (reference para. 2. E) if difficulty is experienced in locating the 

probe when inspecting castellations to the rear of the hub arms.

M. If the inner (LAST) thread does not show on the screen, the hub may be cracked at an angle to the probe 

and should be rejected for further crack examination. See paragraph 4. A. below.

4. Inspection Standard

A. Any crack indication is cause for rejection of the hub. Defect indications may be confirmed, and 

assessment of size made by inspecting magnetically using NDT technique NDT 21M. Refer to Dowty 

Propellers Standard Practices Manual 60-00-00.

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ALERT

Propeller Hub Inspection - Probe Position

Figure 1

61-1043-1

HUB

PROBE

POSITION

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ALERT

APPENDIX B

STATUS REPORT

THE ULTRASONIC INSPECTION OF THE HS748 PROPELLER HUB PORT BUTTRESS THREADS

1. Operator .............................................................

2. Aircraft Serial No. ..............................................

3. Propeller Installation (delete whichever is not applicable)

4. Propeller Serial No. .........................................

5. Hub Serial No. ..................................................

6. Hub total flying hours since new (TSN) ..................... Flying Hours

7. Hub total flying hours since overhaul (TSO) ..................... Flying Hours

8. Crack indications and details if any (illustrate above) ...........................................................................................

..............................................................................................................................................................................

Report ‘Satisfactory’ if no cracks are found.

9. Inspectors stamp or signature ..............................................................................................................................

SECTION A-A

THROUGH HUB PORTS

SHOWING BUTTRESS THREAD

VIEW SHOWING HUB PORTS

MARK WHERE CRACK

OCCURS IN BUTTRESS THREAD

MARK EXTENT OF CRACK IN 

THE BUTTRESS THREAD AROUND

THE HUB BLADE PORT

A

A

61-1031-2 61-1043-2

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Appendix B

Left Right