0 Pratt & Whibley 

A United Technologies Company 

SERVICE BULLETIN 

ENGINE - ROTOR ASSEMBLIES. HIGH PRESSURE COMPRESSOR (HPC) ROTOR NUTS -

REPLACEMENT OF, TO REDUCE RISK OF STRESS CORROSION AT TITANIUM ROTOR DISKS 

MODEL APPLICATION 

PW6122A, PW6124A 

BULLETIN ISSUE SEQUENCE 

PW6000 Series 72-46 

ATA NUMBER 

72-35-00 

UTC/P&W PROPRIETARY INFORMATION 

This document is the property of United Technologies Corporation- Pratt & Whitney (UTC/P&W). You may not possess. 

use. copy or disclose this document or any information in it. for any purpose, including without limitation to design. 

manufacture, or repair parts, or obtain FAA or other government approval to do so. without UTC/P&Ws express written 

permission. Neither receipt nor possession of thiS document alone, from any source. constitutes such permission. 

Possession, use, copying or disclosure by anyone without UTC/P&Ws express written permission is not authorized 

and may result in criminal and/or civil liability. 

Not subject to the EAR per 15 C. F. R. Chapter 1, Part 734.3(b)(3). 

Compliance Category 

6 

P&W Distribution Code 

2645 

March 5/15 

Published in United States of America 

PW6ENG 72-46 

Page 1 of 12 
Pratt & Whitney 

A United Technologies Company 

Summary 

The purpose of this Service Bulletin is to replace High Pressure Compressor (HPC) rotor nuts. 

The replacement of the silver plated rotor nuts with non-silver plated nuts is in order to prevent 

stress corrosion on titanium disks. During engine overhaul, cracks have been found on 7th stage 

compressor rotor disk rear wing initiating from the corrosion area. Stress corrosion was found to 

be caused by interaction between the titanium disk material and silver plating which is used as a 

lubricant on the rotor nut threads. Due to this recent shop finding, all silver plated rotor nuts inside 

the rotor drum will be replaced with non-silver plated nuts to prevent corrosion attack and cracking. 

Planning Information 

Effectivity Data 

Engine Models Applicable 

PW6122A, PW6124A 

Engine Serial Nos. P318104 thru P318140" 

" This estimate of engine serial numbers will be revised, if necessary, when parts are 

installed in engines at Pratt & Whitney. 

NOTE: The engine serial number effectivity data and its related engine model 

identification contained in this Service Bulletin are taken from the records of 

part(s) incorporation during initial manufacture. 

After initial engine manufacture. but before final delivery, P&W may change 

part(s) in the engine or change the model identification of the engine. Such 

action is recorded on FAA337 forms. 

To find Service Bulletin PW6ENG 72-46 models that are applicable, the 

owner/operator of the engine must compare the Service Bulletin List supplied 

with the engine as sent from P&W and the List of Changes incorporated at the 

Airframer from FAA337 forms to the Service Bulletin PW6ENG 72-46 Effectivity 

section. 

Concurrent Requirements 

There are no concurrent requirements. 

Reason 

1. Problem: During scheduled engine overhaul of the HPC rotor. cracking of 7th stage 

compressor rotor disk rear wing has been found in areas of bolt holes. 

2. Cause: Stress corrosion caused by a reaction of silver plating residue from the rotor 

nut threads with the titanium disk material in presence of sodium, sulfur and chloride 

at a specific temperature range. 

3. Solution: Silver plated rotor nuts of all HPC rotor stages to be replaced by new 

non-silver plated nuts during shop visit to eliminate the potential for stress corrosion. 

Description 

Replace the rotor nuts for the bolted joint between the HPC stages 6 to 7, 7 to 9 and 9 

to 11 drum assemblies. 

March 5/15 PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Subject to the restrictions on the cover or first page. 

Not Subject to the EAR per 15 C.F.R. Chapter 1, Part 734.3(b)(3). 

Page 2 
Pratt & Whimey 

A United Technologies Company 

The tightening procedure for the rotor nuts at the three joints is changed to a combined 

torquing and angle of turn procedure. 

NOTE: The new rotor nut standard is made of the same base material, but is not silver 

plated on the internal threads. The new rotor nuts have the same spline drive 

outer geometry. 

Compliance 

Category 6 

Do when the subassembly (i.e. modules, accessories, components, build groups) is 

disassembled sufficiently to give access to the changed part and to all changed spare parts. 

Approval Data 

The part number changes and/or part changes specified in the Material Information section 

and Accomplishment Instructions of this Service Bulletin agree with the applicable Federal 

Aviation Regulations and are FAA-Approved for the engine model(s) given. 

The aircraft Type Certificate (TC) holder has been informed of this change. 

Weight Data 

No Change. 

Electrical Load Data 

Not Applicable. 

Software Accomplishment Summary 

Not Applicable. 

References 

1. Turbojet Engine Standard Practices Manual, Part No. 585005. 

2. PW6122A and PW6124A Turbofan Engines, Illustrated Parts Catalog, Part No. 5407766. 

3. PW6122A and PW6124A Turbofan Engines, Engine Manual, Part No. 5407764. 

Publications Changed 

PW6122A and PW6124A Turbofan Engines, Illustrated Parts Catalog, Part No. 5407766. 

72-35-00, Figure 1, 2, and 4 

PW6122A and PW6124A Turbofan Engines, Engine Manual, Part No. 5407764. 

Interchangeability 

Old and new parts are interchangeable only in sets. 

Information in the Appendix 

Alternate Accomplishment Instructions (No) 

Progression Charts (Yes) 

Added Data (Yes) 

Revision to Table of Limits (No) 

Inspection Procedures (No) 

March 5/15 PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Subject to the restrictions on the cover or first page. 

Not subject to the EAR per 15 C.F.R Chapter 1, Part 734.3(b)(3). 

Page 3 
Pratt & Whitney 

A United Technologies Company 

Material Information 

Material - Cost and Availability 

1. Part prices were not available at the time of SeNice Bulletin publication. Contact Pratt & 

Whitney Spares Management & Logistics for firm quotations. 

2. Part availability information is provided in material data Instructions- Disposition. 

Industry Support Program 

Not Applicable. 

The material data that follows is for each engine. 

NOTE: It is possible to use the Chapter/Section and Figure/Item reference number 

shown below the old part number to find the part in the Illustrated Parts Catalog. 

CAUTION: THE FOLLOWING MATERIAL DATA TABLE(S) ARE ORGANIZED BY 

ILLUSTRATED PARTS CATALOG. ALL PARTS IN THE TABLE(S) MAY OR 

MAY NOT BE APPLICABLE TO ALL THE ENGINE MODELS SHOWN 

IN THE TABLE HEADING. YOU MUST REFER TO THE APPROPRIATE 

ILLUSTRATED PARTS CATALOG FOR ENGINE MODEL APPLICABILITY 

USING THE OLD PART NUMBER (PN) AND CATALOG SEQUENCE 

NUMBER. FAILURE TO INSTALL THE PART(S) IN THE CORRECT 

ENGINE MODEL MAY RESULT IN A CONFIGURATION THAT IS NOT FAA 

APPROVED. 

The material data that follows is for each engine. 

For PW61 22A, PW6124A Engines: 

New PN Qty Estimate of Unit Keyword Old PN Instructions -

Price($) Disposition 

1 B2647 24 .. NUT- OPTION 4301682 (2)(A)(C1 )(01) 

(72-35-70-01-030) 

182647 18 .. NUT- OPTION 4301682 (2)(A)(C1 )(0 1) 

(72-35-70-01 -21 0) 

1B2647 18 * NUT- OPTION 4301682 (2)(A)(C1 )(0 1) 

(72-35-70-02-170) 

1 B2647 18 * NUT- OPTION 4301682 (2)(A)(C 1 )(0 1) 

(72-35-70-04-180) 

Modification and Spares Information 

Estimated part prices are provided when they are available at time of publication. The 

Estimate of Unit Price is only for planning purposes and does not constitute a firm 

quotation. An asterisk(*) is shown where part pricing information was unavailable. In either 

case. contact Pratt & Whitney Spares Management & Logistics for firm quotations. 

Parts Modification Conditions 

(2) The new part is a replacement part only, and cannot be obtained by modification 

of the old part. 

Spare Parts Availability 

March 5/15 PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Subject to the restrictions on the cover or first page. 

Not Subject to the EAR per 15 C.F.R. Chapter 1, Part 734.3(b)(3). 

Page 4 
0 A United Technologies Company 

Pratt & Whibley 

(A) The new part is available. 

(C1) The old part will continue to be supplied for use at other locations. 

(01) Nut Option, PN 182647, consists of a Insert, PN 182643, or PN 182644. or 

182645, or PN 182646. 

Vendor Services or Special Components/Materials 

Not Applicable. 

Material Data for Each Spare Engine 

The material for each spare engine is as stated in the preceding material information 

section. 

Reidentified Parts 

Not Applicable. 

Necessary Tools 

Tool No. 

8059093000 

New Support Equipment that is necessary 

Name Manufacturer 

ST Wrench Atlas Copco 

or 

Wrench with comparable specifications 

Other Material Information Data 

Not Applicable. 

March 5/15 PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Page 5 

Subject to the restrictions on the cover or first page. 

Not subject to the EAR per 15 C.F.R Chapter 1, Part 734.3(b)(3). 
Pratt & Whitney 

A United Technologies Company 

Accomplishment Instructions 

1. Replace the 6th. 9th. and 10th stage Nut-Options, PN 4301682, with PN 182647. At 

engine assembly make the following changes to the engine manual procedures. 

2. In Reference 3, Engine Manual, Chapter/Section 72-35-70, Assembly-07: 

Replace the following step: 

(3)(b) Apply Anti-Seize Paste Compound P06-054 (PWA36246-2) to the threads of the 

18 pins [3]. 

With: 

(3)(b) Apply Anti-Seize Paste Compound P06-054 (PWA36246-2) to threads of the nuts [1] 

and the surface of the nuts [1] which will be in contact with the rotor flange. 

Replace the following step: 

(3)(g) Torque the nuts [1] with the Fixture detail torque adapter and a torque wrench by 

two steps that follow: 

(3)(g)(1) Torque the nuts [1] in by the torque sequence to 57- 631bf-in (6.440- 7.118 N.m). 

NOTE: Do not use a click-stop torque wrench. Use only a torque wrench with drag 

indicator. 

(3)(g)(2) Torque the nuts [1] by the torque sequence to 71- 78 1bf-in (8.022- 8.813 N.m). 

(3)(g)(3) Check the torque of all the nuts [1] in clockwise direction. 

With: 

(3)(g) Torque the nuts [1] with the Fixture detail torque adapter and the tool 8059093000 

ST Wrench by the steps that follow: 

(3)(g)(1) Torque the nuts [1] in by torque sequence to 71.7 -771bf-in (8. 1 - 8.7 Nm). 

(3)(g)(2) Check the torque of all the nuts [1] in clockwise direction. 

3. In Reference 3, Engine Manual, Chapter/Section 72-35-70, Assembly-19: 

Delete the following step: 

(6)(d) Apply Anti-Seize Paste Compound P06-054 (PWA36246-2) to the threads of the 18 

pins on the front of the 9th stage rotor assembly. 

Replace the following step: 

(8) Install the 18 nuts [41] to the HPC rotor assembly as follows. See Figure 1005 (Sheet 

1) and Figure 1005 (Sheet 2). 

(8)(a) Install the PWA 104871 Guide Fixture to the 9th stage rotor assembly [21]. 

(8)(b) Install the 18 nuts [41] with the PWA 104819 Nut Starter to the HPC rotor assembly. 

(8)(c) Torque the 18 nuts (41 ] with the PWA 104820 Torque Adapter and the PWA 104873 

Guide Pin to 60 lb-in (6.8 N.m) by the torque sequence. 

(8)(d) Torque the 18 nuts [41] again by the step above to 260.2 lb-in (29.4 N.m) by the 

torque sequence. 

(8)(e) Check the torque of all of the 18 nuts [41]. 

(8)(f) Remove the Torque Adapter, the Pin, and the Fixture. 

March 5/15 PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Subject to the restrictions on the cover or first page. 

Not Subject to the EAR per 15 C.F.R. Chapter 1, Part 734.3(b)(3). 

Page 6 
0 A United Technologies Company 

Pratt & Whibley 

With: 

(8) Install the 18 nuts [41] to the HPC rotor assembly as follows. See Figure 1005 (Sheet 

1) and Figure 1005 (Sheet 2). 

(8)(a) Install the PWA 104871 Guide Fixture to the 9th stage rotor assembly [21]. 

(8)(b) Apply Anti-Seize Paste Compound P06-054 (PWA36246-2) to threads of the nuts 

[41] and the surface of the nuts [41 ] which will be in contact with the rotor flange. 

(8)(c) Install the 18 nuts [41] with the PWA 104819 Nut Starter to the HPC Rotor Assembly. 

(8)(d) Torque the nuts (41] with the PWA 104820 Torque Adapter and the PWA 104873 

Guide Pin and the tool 8059093000 Wrench to 84.1 - 92.9 lbf-in (9.5 - 10.5 Nm) by the 

torque sequence. 

(8)(e) Torque the 18 nuts [41 ] again by the step above to 246.9-272.6 lbf-in (27.9- 30.8 

Nm) by the torque sequence. 

NOTE: After the pre-torque steps (d) and (e) do not loose all nuts at the same time. 

Loose and tighten finally only one nut at the same time. 

(8)(f) Tighten each nut [41] finally with the tool 8059093000 ST Wrench by the steps that 

follow: 

(8)(f)(1) Loose one nut [41] at a time in torque sequence while maintaining all others tight 

and ensure that nut is separated from flange. 

(8)(f)(2) Torque subsequently nut [41] and measure run-on torque (torque required to 

turn nut due to self-locking feature of nut). 

(8)(f)(3) Record run-on torque of each nut [41]. Minimum allowable run-on torque is 6.5 

lbf-in (0.735 Nm). Otherwise replace nut [41]. 

(8)(f)(4) Torque nut [41] to 26.55- 44.251bf-in (3- 5 Nm) plus the run-on torque noted for 

each nut. Ensure that nut is in contact with flange. 

(8)(f)(5) Then, apply with the PWA 104820 Torque Adapter and the tool 8059093000 

Wrench angle of turn of 53 - 57 degrees. 

(8)(f)(6) Measure and record achieved tightening torque against angle of turn. 

(8)(f)(7) After angle of turn is applied, make sure that final torque is between 221 - 292 

lbf-in (25 - 33 Nm). Otherwise change nut and repeat steps (8)(f)(1) - (8)(f)(7) to reach 

the required torque range. 

(8)(f)(8) Move to next bolt in torque sequence until all nuts are tightened. 

(8)(g) Remove the Torque Adapter, the Pin, and the Fixture. 

Delete the following step: 

(14)(c) Apply Anti-Seize Paste Compound P06-054 (PWA 36246-2) to the threads of 

the bolts [71]. 

Replace the following step: 

(15) Install the 18 nuts [81] between the 7th stage rotor assembly [61] and 8th stage rotor 

assembly [5 1] as follows. See Figure 1010. 

(1 5)(a) Install the PWA 104871 Guide Fixture to the 7th stage rotor assembly [61]. 

March 5/15 PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Subject to the restrictions on the cover or first page. 

Not subject to the EAR per 15 C.F.R Chapter 1, Part 734.3(b)(3). 

Page 7 
Pratt & Whitney 

A United Technologies Company 

(15)(b) Install the 18 nuts [81] with the PWA 104825 Torque Adapter and the PWA 104873 

Guide Pin. 

(15)(c) Torque the 18 nuts [81] with the PWA 104820 Torque Adapter and the Pin to 60 

!b-in (6.8 N.m) by the torque sequence. 

(15)(d) Torque the nuts [81] again with the PWA 104820 Torque Adapter and the Pin to 

260.2 lb-in (29.4 N.m) by the torque sequence. 

(1 5)(e) Check the torque of all of the 18 nuts [81 ]. 

(15)(f) Remove the Fixture. 

With: 

(15) Install the 18 nuts [81] between the 7th stage rotor [61] and the 8th stage rotor 

assembly [51] as follows. See Figure 1010. 

(1 5)(a) Install the PWA 104871 Guide Fixture to the 7th stage rotor assembly [61]. 

(1 5)(b) Apply Anti-Seize Paste Compound P06-054 (PWA36246-2) to threads of the nuts 

[81 ] and the surface of the nuts [81] which will be in contact with the rotor flange. 

(1 5)(c) Install the 18 nuts [81] with the PWA104825 Torque Adapter and the PWA 104873 

Guide Pin. 

(15}(d) Torque the 18 nuts [81] with the PWA 104820 Torque Adapter and the Pin and the 

8059093000 ST Wrench to 84.1 - 92.9 lbf-in (9.5 - 10.5 Nm) by the torque sequence. 

(15)(e) Torque the 18 nuts [81] again by the step above to 246.9- 272.6 lbf-in (27.9-

30.8 Nm) by the torque sequence. 

NOTE: After the pre-torque steps (d) and (e) do not loose all nuts at the same time. 

Loose and tighten finally only one nut at the same time. 

(15)(f) Tighten each nut [81 ] finally with tool8059093000 ST Wrench by the steps that 

follow: 

(15)(f)( 1) Loose one nut [81] at a time in torque sequence while maintaining all others tight 

and ensure that nut is separated from flange. 

(15)(f)(2) Torque subsequently nut [81] and measure run-on torque (torque required to 

turn nut due to self-locking feature of nut). 

(15)(f)(3) Record run-on torque of each nut [81). Minimum run-on torque is 6.5 lbf-in (0. 735 

Nm). Otherwise replace nut [81 ). 

(15)(f)(4) Torque nut [81] to 26.55- 44.251bf-in (3 - 5 Nm) plus the run-on torque noted for 

each nut. Ensure that nut is in contact with flange. 

(15)(f)(5) Then, apply with the PWA 104820 Torque Adapter and the tool 8059093000 

Wrench angle of turn of 53 - 57 degrees. 

(15)(f)(6) Measure and record achieved tightening torque against angle of turn. 

(15)(f)(7) After angle of turn is applied, make sure that final torque is between 221.0 -

301.0 lbf-in (25- 34 Nm). Otherwise change nut and repeat steps (15)(f)(1)- (15)(f)(7) to 

reach the required torque range. 

(1 5)(f)(8) Move to next bolt in torque sequence until all nuts are tightened. 

(15)(g) Remove the Fixture. 

March 5/1 5 PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Subject to the restrictions on the cover or first page. 

Not Subject to the EAR per 15 C.F.R. Chapter 1, Part 734.3(b)(3). 

Page 8 
0 A United Technologies Company 

Pratt & Whitney 

Replace the following Step: 

(19)(d) Install the 24 nuts [101] to the 6th rotor assembly as follows. 

(19)(d)(1) Install the 24 nuts [101] to the rotor assembly (101]. 

(19)(d)(2) Torque the 24 nuts [101] to 57- 631bf-in (6.440- 7.118 N.m) by the torque 

sequence. 

NOTE: Use a torque wrench with drag indicator. 

(19)(d)(3) Torque the nuts [101] to 247- 273 lbf-in (27.907- 30.845 N.m) by the torque 

sequence. 

NOTE: Use a torque wrench with drag indicator. 

(19)(d)(4) Check the torque of the 24 nuts [101]. 

With: 

(19)(d) Apply Anti-Seize Paste Compound P06-054 (PWA36246-2) to threads of the nuts 

[101] and the surface of the nuts [101] which will be in contact with the rotor flange. 

(19)(e) Install the 24 nuts [101] to the 6th rotor assembly [91]. 

(19)(f) Torque the 24 nuts [1 01] with tool 8059093000 Wrench to 84.1 - 92.9 lbf-in (9.5-

10.5 Nm) by the torque sequence. 

(19)(g) Torque the 24 nuts [101] with tool8059093000 Wrench again by the step above to 

246.9 - 272.6 lbf-in (27.9- 30.8 Nm) by the torque sequence. 

NOTE: After the pre-torque steps (f) and (g) do not loose all nuts at the same time. 

Loose and tighten finally only one nut at the same time. 

(1 9)(h) Tighten each nut [1 01] finally with tool 8059093000 ST Wrench by the steps that 

follow: 

(19)(h)(1) Loose one nut [101] at a time in torque sequence while maintaining all others 

tight and ensure that nut is separated from flange. 

(1 9)(h)(2) Torque subsequently nut [1 01] and measure run-on torque (torque required to 

turn nut due to self-locking feature of nut). 

(19)(h)(3) Record run-on torque of each nut [101]. Minimum run-on torque is 6.5 lbf-in 

(0.735 Nm). Otherwise replace nut [101]. 

(19)(h)(4) Torque nut [101] to 26.55- 44.25 lbf-in (3 - 5 Nm) plus the run-on torque noted 

for each nut. Ensure that nut is in contact with flange. 

(19)(h)(5) Then, apply angle of turn of 53- 57 degrees. 

( 19)(h)(6) Measure and record achieved torque against angle of turn. 

(19)(h)(7) After angle of turn is applied, make sure that final torque is between 221 .0 -

301.0 lbf-in (25- 34 Nm). Otherwise change nut and repeat steps (19)(h)(1) - (1 9)(h)(7) to 

reach the required torque range. 

{19)(h)(8) Move to next bolt in torque sequence until all nuts are tightened. 

March 5/15 PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Page 9 

Subject to the restrictions on the cover or first page. 

Not subject to the EAR per 15 C.F.R Chapter 1, Part 734.3(b}(3). 
4301682 

NUT-OPTION 

REPLACE WITH 

182647 

(24 UNITS} 

6523918 

March 5/1 5 

Pratt & Whitney 

A United Technologies Company 

LOCATION OF THE HPC ROTOR NUTS 

72-35-00 

FIGURE 1, Sheet 1 

4301682 

NUT-OPTION 

REPlACE WITH 

182647 

(18 UNITS) 

PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION Page 10 

Subject to the restrictions on the cover or first page. 

Not Subject to the EAR per 15 C.F.R. Chapter 1, Part 734.3(b)(3). 
4301682 

NUT-OPTION 

REPLACE WITH 

182647 

(1 8 UNITS) 

\ 

8523919 

March 5/1 5 

Pratt & Whitney 

A United Technologies Company 

4301682 

NUT-OPTION 

REPLACE WITH 

182647 

(18 UNITS) 

LOCATION OF THE HPC ROTOR NUTS 

72-35-00 

FIGURE 2, Sheet 2 

PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Subject to the restrictions on the cover or first page. 

Not subject to the EAR per 15 C.F.R Chapter 1, Part 734.3(b)(3). 

Page 11 
Pratt & Whitney 

A United Technologies Company 

Appendix 

Parts Progression To Show the Changed Part in Relation to Other Parts 

8523917 

Added Data 

Revision No. 

Original 

HPC ROTOR NUT 

CHART A 

Internal Reference Information 

Reference 

Document 

EC14MM013 

4301682 

ORIGINAL 

182647 

SB 72-46 

Origination 

MTU 

Reference 3, Engine Manual, Chapter/Section 72-35-70, Assembly-07 and Assembly-19, 

Revision 032, dated Aug 01/15 is scheduled to incorporate the assembly changes to this 

Service Bulletin and will take precedence over the Service Bulletin. 

Number values shown in parentheses adjacent to U.S. values are International System of 

units (SI) equivalents. 

March 5/15 PW6ENG 72-46 

UTC/P&W PROPRIETARY INFORMATION 

Subject to the restrictions on the cover or first page. 

Not Subject to the EAR per 15 C.F.R. Chapter 1, Part 734.3(b)(3). 

Page 12