PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2

BULLETIN INDEX LOCATOR

72-30-00
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

MODEL APPLICATION
PW118, PW118A, PW118B, PW119B, PW119C, PW120, PW120A, PW121, PW121A, PW123,
PW123AF, PW123B, PW123C, PW123D, PW123E, PW124B, PW125B, PW126, PW126A, PW127,
PW127B, PW127E, PW127F, PW127G, PW127H, PW127J, PW127M, PW127N

Compliance: CATEGORY 6

Summary: The upper towershaft assembly may be optimized to reduce stress level. This
involves the introduction of a new stiffer assembly with increased resistance to wear.

Feb 21/2019 PW100-72-21936

Revision No. 2: Sep 12/2019 Cover Sheet

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WARNING - PROPRIETARY RIGHTS & EXPORT CONTROLS NOTICE

This bulletin contains proprietary information of Pratt & Whitney Canada Corp. (″P&WC″), which
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providing applicable information regarding the proper use, maintenance, inspection, repair, servicing
and parts application of P&WC products and services, as directed therein. Neither this bulletin nor
any information in it may be disclosed to others, or used for any other purpose, including, without
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If a Government agency or department intends to disclose any information, written notice should be
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Export Classification: This document contains no technical data

 Pratt & Whitney Canada Corp.
1000, Marie-Victorin
Longueuil, Québec, Canada J4G 1A1
Tél. 450-677-9411

12 September 2019

P&WC S.B. No. 21936R2

REVISION TRANSMITTAL SHEET

TURBOPROP ENGINE MODEL PW100

SUBJECT: Pratt & Whitney Canada Service Bulletin No. PW100-72-21936, Rev. No. 2, dated Sep
12/2019 (P&WC S.B. No. 21936R2) UPPER TOWERSHAFT ASSEMBLY -
REPLACEMENT OF

Replace your existing copy of this service bulletin with the attached revised bulletin. Destroy the
superseded copy.

Please retain this Revision Transmittal Sheet with the revised bulletin.

SUMMARY: This revision is issued to:

v update the summary.

v update the reason in Para. 1.C., Planning Information.
v modify part number ‘‘3111957-01’’ to read ‘‘3123810-01’’ in Para. 3.C.,
Accomplishment Instructions.
v modify part number ‘‘3111100-01’’ to read ‘‘3123800-01’’ in Para. 3.C.,
Accomplishment Instructions.
v add ‘‘CML’’ reference in Para. 1.K.
v remove previously deleted items.
v revise Table reference from Table 2 to Table 3 in Para. 4., Appendix.

EFFECT OF REVISION ON PRIOR ACCOMPLISHMENT:

None.

NOTE: A black bar in the left margin indicates a change in that line of text or figure.

REVISION HISTORY:
Original Issue: Feb 21/2019 Revision No. 1: May 07/2019 Revision No. 2: Sep 12/2019

Export Classification: This document contains no technical data

Export Classification: This document contains no technical data
 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

1. Planning Information

A. Effectivity
PW118 (BS698) Engines.
PW118A (BS718) Engines which are before and include Serial No. PCE-115712 and
which are before and include Serial No. PCE-AA0057.
PW118B (BS901) Engines.
PW119B (BS824) Engines.
PW119C (BS878) Engines which are before and include Serial No. PCE-116172 and
which are before and include Serial No. PCE-AZ0006.
PW120 (BS633, BS716) Engines.
PW120A (BS632) Engines.
PW121 (BS717, BS722, BS725) Engines which are before and include Serial No.
PCE-121401 and which are before and include Serial No. PCE-AC0160.
PW121A (BS849) Engines.
PW123 (BS707) Engines which are before and include Serial No. PCE-123358 and
which are before and include Serial No. PCE-AE0207.
PW123B (BS785) Engines which are before and include Serial No. PCE-123358 and
which are before and include Serial No. PCE-AR0070.
PW123C (BS838) Engines which are before and include Serial No. PCE-123358 and
which are before and include Serial No. PCE-AT0020.
PW123D (BS839) Engines.
PW123E (BS869) Engines which are before and include Serial No. PCE-123358 and
which are before and include Serial No. PCE-AW0224.
PW123AF (BS723) Engines which are before and include Serial No. PCE-109091 and
which are before and include Serial No. PCE-AF0187.
PW124B (BS724, BS726, BS896) Engines.
PW125B (BS647, BS794) Engines.
PW126 (BS691) Engines.
PW126A (BS743) Engines.
PW127 (BS774, BS897) Engines.
PW127B (BS812) Engines which are before and include Serial No. PCE-126041 and
which are before and include Serial No. PCE-AS0007.
PW127E (BS850, BS1034) Engines which are before and include Serial No. PCE-127211
and which are before and include Serial No. PCE-AM0117.
PW127F (BS918, BS1033, BS1123) Engines which are before and include Serial No.
PCE-AV0120.
PW127E / PW127F Engines which are before and include Serial No. PCE-EB0369.
PW127G (BS945, BS1316) Engines which are before and include Serial No.
PCE-AX0438.
PW127H (BS964) Engines which are before and include Serial No. PCE-AY0019.
PW127J (BS1018) Engines which are before and include Serial No. PCE-EA0284.
PW127M (BS1237) Engines which are before and include Serial No. PCE-ED1825.

P&WC No. CO-0003417, EC-0010484, EC-0010495

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
Revision No. 2: Sep 12/2019 © 2019 Pratt & Whitney Canada Corp. Page 1 of 19
PRINTED IN CANADA

Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

1. Planning Information (Cont’d)

PW127N (BS1324) Engines.

NOTE: The above effectivity list does not identify engines that have been converted
from one engine model to another engine model via an engine conversion
service bulletin. To clarify the effectivity of converted engines, refer to the PW100
Workscope Planning Guide, P/N 3040879, Converted Engines section.

B. Concurrent Requirements

None.

C. Reason

(1) Problem

The assembly method of the upper towershaft assembly may be optimized.

(2) Cause

The current configuration assembly may cause higher stress level for the towershaft
and associated hardware.

(3) Solution

Introduce a stiffer upper towershaft assembly with increased resistance to wear.

The assembly method is also optimized.

D. Description

Replace the upper towershaft assembly with a new one.

E. Compliance

CATEGORY 6 - P&WC recommends to do this service bulletin when the subassembly

(i.e. module, accessories, components, or build groups) is disassembled
and access is available to the necessary part. Do all spare
subassemblies.

F. Approval

D.O.T./D.A.A. approved.

G. Manpower

No more man-hours are necessary to include this service bulletin at overhaul.

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
Revision No. 2: Sep 12/2019 Page 2 of 19

Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

1. Planning Information (Cont’d)

H. Weight and Balance

None.

I. Electrical Load Data

Not changed.

J. Software Accomplishment Summary

Not changed.

K. References
Illustrated Parts Catalog P/N 3034624 (PW118/118A/118B)
Illustrated Parts Catalog P/N 3038534 (PW119B/119C)
Illustrated Parts Catalog P/N 3034644 (PW120/121/121A)
Illustrated Parts Catalog P/N 3034634 (PW120A/121)
Illustrated Parts Catalog P/N 3036434 (PW123/123B/123C/123D/123E)
Illustrated Parts Catalog P/N 3034540 (PW123AF)
Illustrated Parts Catalog P/N 3037334 (PW124B/127/127E/127F/127M/127N)
Illustrated Parts Catalog P/N 3034934 (PW125B)
Illustrated Parts Catalog P/N 3039724 (PW127B)
Illustrated Parts Catalog P/N 3034924 (PW126/126A)
Illustrated Parts Catalog P/N 3044824 (PW127G)
Illustrated Parts Catalog P/N 3045544 ( PW127H)
Illustrated Parts Catalog P/N 3043394 (PW127J)
Overhaul Manual P/N 3034623 (PW118/118A/118B)
Overhaul Manual P/N 3034643 (PW120/121/121A)
Overhaul Manual P/N 3034633 (PW120A/121)
Overhaul Manual P/N 3036433 (PW123/123B/123C/123D/123E)
Overhaul Manual P/N 3034539 (PW123AF)
Overhaul Manual P/N 3037333 (PW124B/127/127E/127F/127M/127N)
Overhaul Manual P/N 3034933 (PW125B/PW127B)
Overhaul Manual P/N 3034923 (PW126/126A)
Overhaul Manual P/N 3044823 (PW127G)
Overhaul Manual P/N 3045543 ( PW127H)
Overhaul Manual P/N 3043393 (PW127J)
Engine Manual P/N 3038533 (PW119B/119C)
P&WC Consumable Materials List P/N 3043340

L. Publications Affected
Illustrated Parts Catalog P/N 3034624 (PW118/118A/118B)
Illustrated Parts Catalog P/N 3038534 (PW119B/119C)

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
Revision No. 2: Sep 12/2019 Page 3 of 19

Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

1. Planning Information (Cont’d)

Illustrated Parts Catalog P/N 3034644 (PW120/121/121A)

Illustrated Parts Catalog P/N 3034634 (PW120A/121)
Illustrated Parts Catalog P/N 3036434 (PW123/123B/123C/123D/123E)
Illustrated Parts Catalog P/N 3034540 (PW123AF)
Illustrated Parts Catalog P/N 3037334 (PW124B/127/127E/127F/127M/127N)
Illustrated Parts Catalog P/N 3034934 (PW125B)
Illustrated Parts Catalog P/N 3039724 (PW127B)
Illustrated Parts Catalog P/N 3034924 (PW126/126A)
Illustrated Parts Catalog P/N 3044824 (PW127G)
Illustrated Parts Catalog P/N 3045544 ( PW127H)
Illustrated Parts Catalog P/N 3043394 (PW127J)
Overhaul Manual P/N 3034623 (PW118/118A/118B)
Overhaul Manual P/N 3034643 (PW120/121/121A)
Overhaul Manual P/N 3034633 (PW120A/121)
Overhaul Manual P/N 3036433 (PW123/123B/123C/123D/123E)
Overhaul Manual P/N 3034539 (PW123AF)
Overhaul Manual P/N 3037333 (PW124B/127/127E/127F/127M/127N)
Overhaul Manual P/N 3034933 (PW125B/PW127B)
Overhaul Manual P/N 3034923 (PW126/126A)
Overhaul Manual P/N 3044823 (PW127G)
Overhaul Manual P/N 3045543 ( PW127H)
Overhaul Manual P/N 3043393 (PW127J)
Engine Manual P/N 3038533 (PW119B/119C)

M. Interchangeability and Intermixability of Parts

Interchangeability - Refer to Para. 2.C.

Intermixability - Not changed.

2. Material Information

A. Industry Support Information

Not applicable.

B. Material - Cost and Availability

You can get the procurable parts listed in Para. 2.C. from any Pratt & Whitney Canada
Parts Distribution Center.

The estimated total cost of new parts needed to replace old parts is $Quote (US, 2019).

The new parts are scheduled to be available April 2019.

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

C. Material Necessary for Each Engine

The quantity of materials listed in this section is on a per Engine basis.

Est. Unit
List Price
($US, Instructions
New P/N Keyword Old P/N Qty 2019) Disposition
3123798-01 Gearshaft, Spiral Bevel, 3111968-01 1 Quote (A)(D)
Accessory Gearbox
3123808-01 Ring, Split, Bevel Gear 3110575-01 1 Quote (A)(D)
3123809-01 Collar, Gearshaft, Accessory 3110862-01 1 Quote (A)(D)
Gearbox
Spacer, Adjusting 3101390-07 1 (A)(D)
3123805CL Spacer, Adjusting 1 (A)(B)
3123805CL55 Ê Spacer, 0.055-0.056 in. AR Quote
3123805CL56 Ê Spacer, Over 0.056- AR Quote
0.057 in.
3123805CL57 Ê Spacer, Over 0.057- AR Quote
0.058 in.
3123805CL58 Ê Spacer, Over 0.058- AR Quote
0.059 in.
3123805CL59 Ê Spacer, Over 0.059- AR Quote
0.060 in.
3123805CL60 Ê Spacer, Over 0.060- AR Quote
0.061 in.
3123805CL61 Ê Spacer, Over 0.061- AR Quote
0.062 in.
3123805CL62 Ê Spacer, Over 0.062- AR Quote
0.063 in.
3123805CL63 Ê Spacer, Over 0.063- AR Quote
0.064 in.
3123805CL64 Ê Spacer, Over 0.064- AR Quote
0.065 in.
3123805CL65 Ê Spacer, Over 0.065- AR Quote
0.066 in.

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
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Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

Est. Unit
List Price
($US, Instructions
New P/N Keyword Old P/N Qty 2019) Disposition
3123805CL66 Ê Spacer, Over 0.066- AR Quote
0.067 in.
3123805CL67 Ê Spacer, Over 0.067- AR Quote
0.068 in.
3123805CL68 Ê Spacer, Over 0.068- AR Quote
0.069 in.
3123805CL69 Ê Spacer, Over 0.069- AR Quote
0.070 in.
3123805CL70 Ê Spacer, Over 0.070- AR Quote
0.071 in.
3123805CL71 Ê Spacer, Over 0.071- AR Quote
0.072 in.
3123805CL72 Ê Spacer, Over 0.072- AR Quote
0.073 in.
3123805CL73 Ê Spacer, Over 0.073- AR Quote
0.074 in.
OR
3123805CL99 Ê Spacer, 0.095-0.105 in. AR Quote
Bearing Option (IC) 3032625 1 (A)(D)
Ê Bearing, Roller 3010771 Ref.
Ê Bearing, Roller 3100630-01 Ref.
Ê Bearing, Roller 3101630-01 Ref.
Ê Bearing, Roller 3107496-01 Ref.
3126966-01 Bearing, Roller 1 Quote (A)
3123799-01 Gearshaft, Spiral Bevel, 3111969-01 1 Quote (A)(D)
Accessory Gearbox Drive
3123810-01 Washer, Cup 3111957-01 1 Quote (A)(D)
Nut, Plain 3111100-01 1 (A)(D)
3123800-01 Nut, Plain 1 Quote (A)
Spacer, Adjusting 3101390-02 1 (A)(D)

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

Est. Unit
List Price
($US, Instructions
New P/N Keyword Old P/N Qty 2019) Disposition
3134164CL Spacer, Adjusting 1 (A)(B)
3134164CL97 Ê Spacer, 0.097-0.098 in. AR Quote
3134164CL98 Ê Spacer, Over 0.098- AR Quote
0.099 in.
3134164CL99 Ê Spacer, Over 0.099- AR Quote
0.100 in.
3134164CL100 Ê Spacer, Over 0.100- AR Quote
0.101 in.
3134164CL101 Ê Spacer, Over 0.101- AR Quote
0.102 in.
3134164CL102 Ê Spacer, Over 0.102- AR Quote
0.103 in.
3134164CL103 Ê Spacer, Over 0.103- AR Quote
0.104 in.
3134164CL104 Ê Spacer, Over 0.104- AR Quote
0.105 in.
3134164CL105 Ê Spacer, Over 0.105- AR Quote
0.106 in.
3134164CL106 Ê Spacer, Over 0.106- AR Quote
0.107 in.
3134164CL107 Ê Spacer, Over 0.107- AR Quote
0.108 in.
3134164CL108 Ê Spacer, Over 0.108- AR Quote
0.109 in.
3134164CL109 Ê Spacer, Over 0.109- AR Quote
0.110 in.
3134164CL110 Ê Spacer, Over 0.110- AR Quote
0.111 in.
3134164CL111 Ê Spacer, Over 0.111- AR Quote
0.112 in.
3134164CL112 Ê Spacer, Over 0.112- AR Quote
0.113 in.

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

Est. Unit
List Price
($US, Instructions
New P/N Keyword Old P/N Qty 2019) Disposition
3134164CL113 Ê Spacer, Over 0.113- AR Quote
0.114 in.
3134164CL114 Ê Spacer, Over 0.114- AR Quote
0.115 in.
OR
3134164CL999 Ê Spacer, 0.140-0.150 in. AR Quote
(A) RESTRICTED INTERCHANGEABILITY - (ATA 200 Explanation Code 07):
All parts are interchangeable as a complete set.
(B) P/N 3123805CL and 3134164CL is not procurable, select appropriate class.
(C) Discard the part if it is unserviceable. Return a serviceable part to stock.
(D) Discard. Do not use again in any application.

D. Reidentified Parts

None.
E. Tooling - Price and Availability

Est. Price
Tool No. Nomenclature ($US, 2019) Delivery
PWC54907 Pusher Quote
PWC89837 Hydraulic Cylinder Quote
PWC57100 Hydraulic Jack Quote
PWC56100 Hydraulic Jack Quote
3. Accomplishment Instructions

A. Remove the parts in the Old P/N list in Para. 2.C., Material Information, in accordance
with the overhaul manual instructions:

v Ref. OHM 72-30-00 COMPRESSOR SECTION - DISASSEMBLY. (For engines

PW118/118A/118B/120/120A/121/121A/123/123B/123C/123D/123E/123AF/
124B/125B/126/126A/127/127B/127D/127E/127F/127J/127H/127M/127N)
v Ref. OHM 72-31-03 DISASSEMBLY-01. (For engines PW119B/119C)
B. Install the parts in the New P/N list in Para. 2.C., Material Information, in accordance
with the overhaul manual instructions :

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

3. Accomplishment Instructions (Cont’d)

v Ref. OHM 72-03-00 TURBOMACHINERY (PW118) - ASSEMBLY-1 or -2 or -3.

v Ref. OHM 72-03-00 TURBOMACHINERY (PW118A, PW118B) - ASSEMBLY-1 or -2.
v Ref. OHM 72-03-00 TURBOMACHINERY- ASSEMBLY-2 or -3. (For engines
PW120/120A/121/121A/123/123B/123C/123D/123E/123AF/124B/125B/126/126A/127/
127B/127D/127E/127F/127J/127H/127M/127N).
v Ref. EM 72-31-03 ASSEMBLY-01. (For engines PW119B/119C).
v Ref. EM 72-31-10 ASSEMBLY-01. (For engines PW119B/119C).

NOTE: During engine testing and if there is bevel box vibration, this procedure (for
Post-Gears) should be used when having to index the gear.

CAUTION: DO NOT HEAT THE BEVEL SPIRAL GEARSHAFT OR COOL THE BEVEL
GEARSHAFT.

C. Assemble bevel gearshaft P/N 3123798-01, bevel spiral gearshaft P/N 3123799-01,
gearshaft collar P/N 3123809-01 and split ring P/N 3123808-01 as per OHM and
Ref. Fig. 2 with the differences that follow:

(1) Preheat collar P/N 3123809-01 to 350 °F for 15 mins.

(2) Install split ring P/N 3123808-01 (Ref. OHM).

(3) Install gearshaft collar P/N 3123809-01 on bevel gearshaft P/N 3123798-01.

(4) Install pusher (PWC54907) and cylinder (PWC89837) on bevel gearshaft

(towershaft). Attach hydraulic pump (PWC56100 or PWC57100) to cylinder. Apply
load of 324 to 370 PSI.

(5) Remove tools.

(6) Visually check gap of split rings (Ref. Fig. 2, Section B-B).

NOTE: Make sure that gap between rings is even and is located in center of
gearshaft slots.

(7) Install pusher (PWC54907) and cylinder (PWC89837) on bevel gearshaft

(towershaft). Attach hydraulic pump (PWC56100 or PWC57100) to cylinder. Apply
load of 550 PSI +/- 25 PSI.

(8) Remove tools.

(9) Install selected spacer P/N 3123805CL (Ref. Dim. K).

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

3. Accomplishment Instructions (Cont’d)

(10) Bevel spiral gearshaft P/N 3123799-01 must be installed without heating and the
bevel gearshaft P/N 3123798-01 without cooling.

(11) Put engine oil (PWC03-001) on three places of the inner splines of the spiral bevel
gearshaft P/N 3123799-01 (Ref. Fig. 2, Sheet 2).

(12) Install bevel spiral gearshaft P/N 3123799-01 on bevel gearshaft P/N 3123798-01.

(13) Install pusher (PWC54907) by a minimum of 5 threads until it contacts bevel

gearshaft face. Install cylinder (PWC89837) and attach hydraulic pump
(PWC56100 or PWC57100).

(14) Apply load of 1850 PSIG +/- 35 PSIG.

(15) Remove load.

(16) Remove tools.

(17) Install cupwasher P/N 3123810-01 and nut P/N 3123800-01.

(18) Torque nut P/N 3123800-01, (F & C Ref. No. 1711) as follows:

NOTE: Do not lubricate nut.

(a) Torque nut to 190 to 215 lbf.in (21.47 - 24.29 Nm).

(b) Loosen to zero lbf.in (0.00 Nm) and torque nut again to 190 lbf.in (21.47 Nm)
minimum.

(c) Final torque must not exceed 215 lbf.in (24.29 Nm).

D. Write the accomplishment of P&WC S.B. No. 21936 in the engine module log book.

4. Appendix

A. Refer to Figure 1 for parts progressions.

B. Refer to Fig. 2, Table 1 and 2 for Fits.

C. Refer to Fig. 2, Table 3 for Torque and Stretch.

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
Revision No. 2: Sep 12/2019 Page 10 of 19

Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

3106201−01
BASIC for
PW126

3106231−01
SB20207
Improved Accessory Gearbox
CC 6 PRC 02

3111958−01
SB20223
Improved Accessory
Gearshaft
CC 5

3111968−01
SB20285
BASIC for PW124B, PW126A, PW127,
PW127B, PW127E, PW127F,
PW127G, PW127H, PW127J
PW127M, PW127N
Improved Spiral Bevel Gearshaft
CC 5

3123798−01
SB21936
Improved Upper
Towershaft Assembly
CC 6 PRC 07

(For Engines PW124B/126/126A/127/127B/127E/127F/127G/127H/127J/127M/127N)

ICN-00198-G000027788-001-01
AGB Spiral Bevel gearshaft - Parts Progression
Figure 1 (Sheet 1 of 4)

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Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
Revision No. 2: Sep 12/2019 Page 11 of 19

Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

3106201−01
BASIC for
PW118

3106231−01
BASIC for PW118A/123
SB20079
Improved Accessory Gearbox
CC 6

3111958−01
SB20223
Improved Gearshaft and
Keywasher
CC 5

3111968−01
SB20285
BASIC for PW118B/119B/
119C/123B/123C/123D/
123E/123AF
Improved Spiral Bevel Gearshaft
CC 5

3123798−01
SB21936
Improved Upper Towershaft
Assembly
CC 6 PRC 07

(For Engines PW118/118A/118B/119B/119C/123/123B/123C/123D/123E/123AF)

ICN-00198-G000027789-001-01
AGB Spiral Bevel gearshaft - Parts Progression
Figure 1 (Sheet 2)

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
Revision No. 2: Sep 12/2019 Page 12 of 19

Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

3108284−01
BASIC

3106231−01
SB20207
Improved Accessory Gearbox
Drive Arrangement
CC 6

3111958−01
SB20223
Improved Gearshaft and
Keywasher
CC 5

3111968−01
SB20285
Improved Spiral Bevel
Gearshaft
CC 5

3123798−01
SB21936
Improved Upper Towershaft
Assembly
CC 6 PRC 07

(For Engines PW125B)

ICN-00198-G000027790-001-01
AGB Spiral Bevel gearshaft - Parts Progression
Figure 1 (Sheet 3)

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
Revision No. 2: Sep 12/2019 Page 13 of 19

Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

3106202−01
BASIC for
PW120/120A

3106201−01
SB20052
BASIC for PW121
Improved Locking
Arrangement
CC 7

3106231−01
SB20079
Improved Accessory
Gearbox
CC 6

3111958−01
SB20223
Improved Gearshaft
and Keywasher
CC 5

3111968−01
SB20285
BASIC for PW121A
Improved Spiral
Bevel Gearshaft
CC 5

3123798−01
SB21936
Improved Upper Towershaft
Assembly
CC 6 PRC 07

(For Engines PW120/120A/121/121A)

ICN-00198-G000027791-001-01
AGB Spiral Bevel gearshaft - Parts Progression
Figure 1 (Sheet 4)

P&WC Proprietary Information. Subject to the restrictions on the back of the locator
Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
Revision No. 2: Sep 12/2019 Page 14 of 19

Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

BEVEL SPIRAL GEARSHAFT

P/N 3111969−01 (PRE−SB)
P/N 3123799−01 (POST−SB)

1711
1311

1314 A 1059 1201

(REF.)
−AE− DIA. 1055 32 MAX.

DIM. K

POINT V DIM. M4

DIRECTION N
DIM. G

BEVEL GEARSHAFT
P/N 3111968−01 (PRE−SB)
P/N 3123798−01 (POST−SB)

INNER RING
(REF.)

ICN-00198-G000025303-001-01
Upper Towershaft Assembly - Fits and Clearance
Figure 2 (Sheet 1 of 2)

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Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
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Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

GAP
SLOT

BEVEL SPLIT RING

SLOT
GAP

SECTION B−B
LUBRICATE HERE

B
GEARSHAFT COLLAR
B P/N 310862−01 (PRE−SB)
P/N 3123809−01 (POST−SB)
BEVEL SPLIT RING
P/N 3110575−01 (PRE−SB)
P/N 3123808−01 (POST−SB)

DETAIL A

ICN-00198-G000027882-001-01
Upper Towershaft Assembly - Fits and Clearance
Figure 2 (Sheet 2)

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Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

4. Appendix (Cont’d)

TABLE 1, FITS

DIMENS. FOR REF.

REF. NAME INCH (mm) LIMITS INCH (mm)

MIN MAX MIN MAX

1059 SPLINE DATA

1 GEARSHAFT - SPIRAL BEVEL ACCESSORY DRIVE,
ASSY OF INTERNAL SPLINE

(A) EFFECTIVE SPACE 0.0491

WIDTH (1.247)

(B) 0.0516
ACTUAL SPACE WIDTH
(1.311)

2 GEARSHAFT - BEVEL, ACCESSORY GEARBOX DRIVE

(A) EFFECTIVE TOOTH 0.0491

THICKNESS (1.247)

(B) ACTUAL TOOTH 0.0431

THICKNESS (1.095)

3 FIT

MIN EFFECTIVE 0.0000

(0.000)

MAX ACTUAL 0.0085

(0.216)

Note: Lubricate with engine oil.

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Feb 21/2019 The export control classification with respect to this document is contained on the back of the locator. PW100-72-21936
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Export Classification: This document contains no technical data

 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

4. Appendix (Cont’d)

TABLE 2, Fits and Clearances

Dim. for Ref. Limits

inches (mm) inches (mm)
REF.
NO. IFR Name Min. Max. Min. Max. Replace

Post-SB21936
1055 Gearshaft, Spiral Bevel 0.9432 0.9435
Accessory Drive Assy (23.957) (23.965)
Of 0.0014 0.0021
(0.036) (0.053)
Bearing Roller Journal 0.9449 0.9453
(24.000) (24.011)
Post-SB21936
1311 Gearshaft, Spiral 0.3854 0.38565
Bevel, Accessory (9.789) (9.796)
Gearbox Drive (46
Teeth) 0.00065 T 0.0001 T
Gearshaft, Spiral 0.3850 0.3853 (0.017)T (0.003)T
Bevel, Accessory (9.779) (9.787)
Gearbox Drive (18
Teeth)

NOTE: Lubricate with engine oil.

Post-SB21936
1314 Gearshaft, Spiral 0.5805 0.5808
Bevel, Accessory (14.745) (14.752)
Gearbox Drive (46
Teeth) 0.0007 T 0.0001 T
Gearshaft, Spiral 0.5801 0.5804 (0.018)T (0.003)T
Bevel, Accessory (14.735) (14.742)
Gearbox Drive (18
Teeth)

NOTE: Lubricate with engine oil.

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 21936R2
TURBOPROP ENGINE
UPPER TOWERSHAFT ASSEMBLY - REPLACEMENT OF

4. Appendix (Cont’d)

TABLE 3, Torque and Stretch

REF. No. NOMENCLATURE LIMITS INCH (mm)

MIN MAX REPL.
1711 Nut, Bearing Retaining and Accessory
Gearbox Drive Shaft (Top Bearing):

Pre-SB v Torque tighten to 280 to 315 lbf.in (31.64

- 35.59 Nm).
v Loosen to 0 lbf.in (0.0 Nm) and torque
the nut again to 280 lbf.in (31.64 Nm)
minimum.
v Final torque must not exceed 315 lbf.in
(35.59 Nm).
Post-SB v Torque tighten to 190 to 215 lbf.in
(21.47 - 24.29 Nm).
v Loosen to 0 lbf.in (0.00 Nm) and torque
the nut again to 190 lbf.in (21.47 Nm)
minimum.
v Final torque must not exceed 215 lbf.in
(24.29 Nm).
v Do not lubricate.

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