Service Bulletin No: 27-021 Date: Jan 20/15

Rev. No. Date: Page 1 of 12

Service Bulletin No: 27-021 Ref No: 331

Modification No: EC-14-0549, EC-14-0714 ATA Chapter: 27

SERVICE BULLETIN

PILATUS AIRCRAFT LTD, STANS, SWITZERLAND

FLIGHT CONTROLS - AILERON CONTROL SYSTEM

AILERON TAB COUNTER BALANCE WEIGHT INCREASE 

1. Planning Information

A. Effectivity

PC-12/47 aircraft MSN 684 thru MSN 888 and PC-12/47E aircraft MSN 545, 1001 thru 1520. 

Aileron trim tab assemblies P/N 527.15.12.037 or 527.15.12.038 held as spare.

Aileron assemblies P/N 557.05.12.015 / 016 / 017 / 018 held as spare.

This modification will be embodied on PC-12/47E aircraft MSN 1521 and up at production.

B. Concurrent Requirements

None.

C. Reason

During a continued airworthiness review, Pilatus Aircraft Ltd. has identified a potentially unsafe 

condition that could result from a disconnected aileron trim tab occurring above an altitude of 

10,000 feet. While there has been no case of a disconnected tab nor any other in-flight control 

disconnection on record for the entire PC-12 fleet, all owners and operators should implement 

this modification to provide improved stability and damping qualities by increasing the weight of 

the aileron tab counter balance.

D. Description

This Service Bulletin gives the data and instructions necessary to replace the aileron tab counter 

balance weight. The old counter balance weight has a diameter of 1.25 in. (31,75 mm) and a 

thickness of 0.34 in. (8,70 mm). The new counter balance weight has a diameter of 1.46 in. 

(37,20 mm) and a thickness of 0.39 in. (10,00 mm).

E. Compliance

Mandatory.

Required at next Annual Inspection, but no later than 29 February 2016.
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 2 of 12

SERVICE BULLETIN

F. Approval

The technical content of this document is approved under the authority of 

DOA No. EASA. 21J. 357.

PILATUS advises Operators/Owners to check with their designated Airworthiness Authority for 

any changes, local regulations or sanctions that may affect the embodiment of this Service 

Bulletin.

G. Copyright

© Pilatus Aircraft Ltd. This document contains proprietary information that is protected by 

copyright. All rights are reserved. No part of this document may be copied, reproduced or 

translated to other languages without the prior written consent of Pilatus Aircraft Ltd.

H. Manpower

NOTE: Man-hours do not include drying time for paints.

I. Weight and Balance

Weight Change +0,060 kg

Moment Change +0,392 kg m

J. Electrical load Data

No change.

K. Software

No change.

L. References

NOTE: Throughout this Service Bulletin, references are given without the model prefix.

For PC-12, PC-12/45 and PC-12/47 aircraft, prefix references with 12-A. 

For PC-12/47E aircraft, prefix references with 12-B.

Aircraft Maintenance Manual (AMM) 

Task Man-hours

Part A

Manhours

Part B

Preparation 1.0 -

Modification 1.0 1.0

Installation 0.5 1.0

Close-Up 3.0 -

TOTAL MAN-HOURS 5.5 2.0

 20-31-00-00A-070A-A 24-00-00-00A-901A-A 57-60-02-00A-920A-A
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 3 of 12

SERVICE BULLETIN

Structural Repair Manual (SRM)

M. Publications Affected

IPC, SRM.

N. Interchangeability of Parts

Not interchangeable.

51-60-01-00A-276A-A
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 4 of 12

SERVICE BULLETIN

2. Material Information

A. Material - Price and Availability

Customers are advised that the standard lead time for parts may be up to two months.

If you require more information about this modification, please contact us as follows:

Operators are requested to advise Pilatus Aircraft Ltd, of the Manufacturer’s Serial Number 

(MSN) and the flying hours of aircraft which are affected by this Service Bulletin.

B. Warranty

Credit will be issued for parts and labour for all affected aircraft on approval of a warranty claim, 

provided the work is accomplished by an authorised Service Center within 12 months of the 

issue date of this Service Bulletin.

C. Material Necessary

NOTE: Part Numbers given in this Service Bulletin are correct at the time of approval. Pilatus 

Aircraft Ltd. reserves the right to change the part numbers as necessary. Part numbers 

of items delivered with the Modification Kit are correct when the kit is dispatched. This 

could lead to differences between those part numbers quoted in this Service Bulletin 

and the Modification Kit if parts are superseded. Operators are requested to check the 

IPC for delivered parts which differ from those listed in the Service Bulletin Materials Kit 

List.

PILATUS AIRCRAFT LTD

CUSTOMER SUPPORT MANAGER

CH-6371 STANS

SWITZERLAND

General Aviation:

Tel: + 41 41 619 3333

Fax: + 41 41 619 7311

eMail: SupportPC12@pilatus-aircraft.com

PILATUS BUSINESS AIRCRAFT LTD

PRODUCT SUPPORT DEPARTMENT

11755 AIRPORT WAY

BROOMFIELD, CO 80021

UNITED STATES OF AMERICA

Tel: +1 303 465 9099

Fax: +1 303 465 6040

eMail: SupportPC12@PilBal.com

PILATUS AUSTRALIA PTY LTD

17 JAMES SCHOFIELD DRIVE

ADELAIDE AIRPORT SA 5950

AUSTRALIA

Tel: +61 8 8238 1600

Fax: +61 8 8234 4499

Free Call: +61 1800 PILATUS (745 2887)

eMail: SupportPC12@pilatus.com.au
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 5 of 12

SERVICE BULLETIN

(1) Parts to be ordered from Pilatus for Part A

(2) Parts to be ordered from Pilatus for Part B

D. Operator Supplied Materials (Ref. AMM, 20-31-00-00A-070A-A)

E. Tooling - Cost and Availability

None.

New Part No. Description Old Part No. Qty Disp. 

Code

Fig Item

527.15.12.105 COUNTER BALANCE 

WEIGHT

527.15.12.102 2 D

Disposition Codes: D - Discard / N - New / R - Return to Pilatus

New Part No. Description Old Part No. Qty Disp. 

Code

Fig Item

527.15.12.105 COUNTER BALANCE 

WEIGHT

527.15.12.102 1 D

Disposition Codes: D - Discard / N - New / R - Return to Pilatus

Material No. Description Qty Remarks

940.17.02.502 COTTER PIN 2

P02-008 LOCKWIRE A/R

939.27.81.018 RIVET NAS1097AD4 A/R Grip length to suit

P07-007 EPOXY PRIMER A/R

P08-073 SEALANT A/R P08-073 for EU. P08-020 is an 

alternative product and 

available for USA
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 6 of 12

SERVICE BULLETIN

3. Accomplishment Instructions - Part A On-Aircraft

A. Preparation

(1) Energize the aircraft electrical system, refer to AMM 24-00-00-00A-901A-A.

(2) Extend the flaps to 40°.

(3) De-energize the aircraft electrical system, refer to AMM 24-00-00-00A-901A-A.

(4) Put a warning sign in the cockpit to warn “DO NOT MOVE FLYING CONTROLS”.

(5) Remove the left and right aileron, AMM 57-60-02-00A-920A-A.

B. Modification

(1) If installed, remove the trim tab from the aileron, refer to Figure 1:

(a) Remove and discard the cotter pin (4).

(b) Remove the nut (5) and washer (6) from the control rod bolt (9).

(c) Remove the control rod bolt (9) from the trim tab brackets.

(d) Disconnect the bonding lead (8) from the bolt (9).

(e) Disconnect the control rod eye end (7) from the trim tab (1).

(f) Remove and discard the lockwire from the trim tab hinge pin (3) and the lockwire tab 

(2) on the trim tab.

(g) Hold the trim tab (1) then remove and keep the hinge pin (3).

(h) Remove the trim tab from the aileron.

Refer to Figure 2.

(2) Carefully remove the two rivets (12) that hold the counter balance weight (10) to the 

aileron trim tab rib (1).

(3) Remove the existing counter balance weight (10) from the trim tab.

NOTE: The counter balance weight may have sealant on the mating surface with the 

trim tab rib.

(4) Make sure that the surface finish on the trim tab rib (1) is clean and undamaged. Reprotect 

the rib as necessary.

(5) Use sealant (Mat. No. P08-073) to wet assemble. Put the new counter balance weight (11) 

(P/N 527.15.12.105) in position on the trim tab rib (1).

(6) Use sealant (Mat. No. P08-073) to wet assemble. Install two new rivets (12) (P/N 

939.27.81.018) to hold the counter balance weight (11). Make sure that the countersunk 

rivet heads are in the trim tab rib.
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 7 of 12

SERVICE BULLETIN

(7) Apply epoxy primer (Mat. No. P07-007) to the new counter balance weight and rivet 

heads.

(8) Let the epoxy primer dry.

(9) Apply the applicable surface finish as needed and let the paint dry.

(10) Part mark the modified item(s) with a permanent marker as follows:

C. Installation

Refer to Figure 1.

(1) Install the aileron trim tab on the aileron:

(a) Align the trim tab hinge with the hinge half on the aileron.

(b) Install the trim tab hinge pin (3).

(c) Safety the trim tab hinge pin (3) with lockwire (Mat. No. P02-008) to the lockwire tab 

(2) on the trim tab.

(d) Put the control rod eye end (7) in the trim tab brackets.

(e) Install the bonding lead (8) on the control rod bolt (9).

(f) Install the control rod bolt (9) through the trim tab brackets and the control rod eye 

end (7).

(g) Install the washer (6) and the nut (5) on the bolt (9).

(h) Safety the nut (5) with a new cotter pin (P/N 940.17.02.502) (4).

D. Close Up

(1) Do the procedure to balance the ailerons, SRM 51-60-01-00A-276A-A.

(2) Install the left and right aileron, AMM 57-60-02-00A-920A-A.

(3) Make sure that the work area is clean and clear of tools and other items.

E. Documentation

(1) Record in the aircraft logbook that this Service Bulletin has been accomplished.

Description New P/N Old P/N

Trim Tab LH 527.15.12.043 527.15.12.037

Trim Tab RH 527.15.12.044 527.15.12.038
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 8 of 12

SERVICE BULLETIN

4. Accomplishment Instructions - Part B Spares

A. Modification

(1) If installed, remove the trim tab from the aileron, refer to Figure 1:

(a) Remove and discard the cotter pin (4).

(b) Remove the nut (5) and washer (6) from the control rod bolt (9).

(c) Remove the control rod bolt (9) from the trim tab brackets.

(d) Disconnect the bonding lead (8) from the bolt (9).

(e) Disconnect the control rod eye end (7) from the trim tab (1).

(f) Remove and discard the lockwire from the trim tab hinge pin (3) and the lockwire tab 

(2) on the trim tab.

(g) Hold the trim tab (1) then remove and keep the hinge pin (3).

(h) Remove the trim tab from the aileron.

Refer to Figure 2.

(2) Carefully remove the two rivets (12) that hold the counter balance weight (10) to the 

aileron trim tab rib (1).

(3) Remove the existing counter balance weight (10) from the trim tab.

NOTE: The counter balance weight may have sealant on the mating surface with the 

trim tab rib.

(4) Make sure that the surface finish on the trim tab rib (1) is clean and undamaged. Reprotect 

the rib as necessary.

(5) Use sealant (Mat. No. P08-073) to wet assemble. Put the new counter balance weight (11) 

(P/N 527.15.12.105) in position on the trim tab rib (1).

(6) Use sealant (Mat. No. P08-073) to wet assemble. Install two new rivets (12) (P/N 

939.27.81.018) to hold the counter balance weight (11). Make sure that the countersunk 

rivet heads are in the trim tab rib.

(7) Apply epoxy primer (Mat No. P07-007) to the new counter balance weight and rivet heads.

(8) Let the epoxy primer dry.

(9) Apply the applicable surface finish as needed and let the paint dry.

(10) Part mark the modified item with a permanent marker as follows:

Description New P/N Old P/N

Trim Tab LH 527.15.12.043 527.15.12.037
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 9 of 12

SERVICE BULLETIN

B. Installation

Refer to Figure 1.

(1) If needed, install the aileron trim tab on the aileron:

(a) Align the trim tab hinge with the hinge half on the aileron.

(b) Install the trim tab hinge pin (3).

(c) Safety the trim tab hinge pin (3) with lockwire (Mat. No. P02-008) to the lockwire tab 

(2) on the trim tab.

(d) Put the control rod eye end (7) in the trim tab brackets.

(e) Install the bonding lead (8) on the control rod bolt (9).

(f) Install the control rod bolt (9) through the trim tab brackets and the control rod eye 

end (7).

(g) Install the washer (6) and the nut (5) on the bolt (9).

(h) Safety the nut (5) with a new cotter pin (P/N 940.17.02.502) (4).

C. Close Up

(1) Do the procedure to balance the aileron, SRM 51-60-01-00A-276A-A.

Trim Tab RH 527.15.12.044 527.15.12.038

Description New P/N Old P/N
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 10 of 12

SERVICE BULLETIN

Aileron Trim Tab - Removal/Installation

Figure 1 

7

4

8

A

3

6

A

LH SHOWN

RH OPPOSITE

1

2

5

9

B

SB2546
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 11 of 12

SERVICE BULLETIN

Aileron Trim Tab Mass Balance Weight - Removal/Installation

Figure 2

SB2547

B

1

10

11

12
Service Bulletin No: 27-021 Date: Jan 20/15

Rev No. Date: Page 12 of 12

SERVICE BULLETIN

INTENTIONALLY BLANK