Service Bulletin No: 53-008 Ref No: 148

Modification No: Inspection ATA Chapter: 53

SERVICE BULLETIN

PILATUS AIRCRAFT LTD. STANS, SWITZERLAND

Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 1 of 18

FUSELAGE - GENERAL

DO A CHECK OF THE MATERIAL SPECIFICATION USED IN THE MANUFACTURE OF THE ENGINE 

MOUNT FITTINGS AND, IF NECESSARY, DO A CHECK FOR CRACKS WITH A BOROSCOPE

1. Planning Information

A. Effectivity

PC-7 aircraft MSN 101 thru MSN 618.

All engine mount fittings (P/N 112.35.07.152) held as spare or in stock.

B. Concurrent Requirements

None.

C. Reason

(1) Problem

An operator reported Stress Corrosion Cracking (SCC) on the engine mount fittings.

(2) Cause

Initially the material specification of the parts was AA2024-T351. The material specification 

was subsequently changed to AA2124-T851 to decrease the risk of stress corrosion.

NOTE: Some customers Structural Repair Manual (SRM) can identify the engine 

mounting-frame attachment-fittings as made from SNV-L748.5. This is an 

equivalent to AA2024-T351.

(3) Solution

Do a one time inspection of the four engine mount fittings to:

(a) Check the material specification of the fittings.

(b) If the fittings are made from AA2124-T851, make an entry in the aircraft logbook as 

required in paragraph 3.F.(3).

(c) If the fittings are made from AA2024-T351, do a one time inspection with a 

boroscope for cracks.

(d) If cracks are found, contact Pilatus.

NOTE: Mandatory inspections will be added to Chapter 5 of the Aircraft 

Maintenance Manual (AMM). The inspections will give instructions on how 

to examine the four engine mount fittings for cracks. The inspections will 

only be applicable to parts made from AA2024-T351.
Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 2 of 18

SERVICE BULLETIN

NOTE: A Service Bulletin will be issued to give instructions and data on how to 

replace the parts made from AA2024-T351. The new parts are made from 

AA2124-T851. Parts that are replaced with those made from AA2124-

T851 will cancel the requirement for the mandatory repetitive inspections.

D. Description

This Service Bulletin gives the data and instructions necessary to:

(1) Check the material specification of the fittings.

(2) If the fittings are made from AA2124-T851, make an entry in the aircraft logbook of the 

new part number.

(3) If the fittings are made from AA2024-T351, do a one time inspection with a boroscope for 

cracks.

These instructions are applicable to the left and right, upper and lower, engine mount fittings, P/N 

112.35.07.152.

E. Compliance

Mandatory.

Accomplishment required not later than 90 days after the effective date of this Service Bulletin.

F. Approval

The technical content of this Service Bulletin is approved under the authority of Letter of DOA 

Acceptance ref. FOCA.21J.002.

Pilatus advises Operators/Owners to check with their delegated Airworthiness Authorities for any 

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

G. Copyright Information

© 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.
SERVICE BULLETIN

Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 3 of 18

H. Manpower 

I. Weight and Balance

(1) Weight Change

Not changed.

(2) Moment Change

Not changed.

J. Electrical Load Data

Not changed.

K. Software

Not changed.

L. References

Aircraft Maintenance Manual (AMM): 12-00-00, 20-31-00, 25-10-00.

M. Publications Affected

AMM, Chapter 05.

Structural Repair Manual (SRM): 53-10-00.

N. Interchangeability of Parts

Not applicable.

Total

Preparation 2.0

Eddy-current conductivity measurement-test 0.5

Boroscope inspection (If Necessary) 2.0

Close up 2.5

TOTAL MAN-HOURS 7.0
Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 4 of 18

SERVICE BULLETIN

2. Material Information

Operators who require more information should contact:

PILATUS AIRCRAFT LTD,

INTEGRATED LOGISTIC SUPPORT MANAGER,

CH 6371 STANS, Tel: +41 41 619 66 30

SWITZERLAND Fax: +41 41 610 33 51

A. Material - Price and Availability 

NOTE: Kit No. 500.60.09.146 is the kit for the reference pieces used to help identify the 

material specification of the suspect parts. One kit is required for each fleet of aircraft.

B. Material Necessary for Each Aircraft

(1) Material to be Procured

Kit No. 500.60.09.146 has these parts:

NOTE: One kit is required for each fleet of aircraft.

(2) Operator Supplied Materials (Ref. AMM 20-31-00) 

C. Material Necessary for Each Spare

None.

D. Re-identified Parts

If the engine mount fittings, either installed on the aircraft or held as spare, are made from 

AA2124-T851, their part numbers will change as follows:

KIT NUMBER PRICE AVAILABILITY

500.60.09.146 Contact address above Contact address above

PART No. DESCRIPTION QTY REMARKS

513.57.09.149 AA2024-T351 REFERENCE PLATE 1

513.57.09.150 AA2124-T851 REFERENCE PLATE 1

MATERIAL NO. DESCRIPTION QTY REMARKS

P01-010 SOLVENT A/R Or equivalent

P02-031 ABSORBENT PAPER A/R Or equivalent

DESCRIPTION OLD PART NUMBER RE-IDENTIFIED PART NUMBER

ENGINE MOUNT FITTING 112.35.07.152 553.10.07.033
SERVICE BULLETIN

Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 5 of 18

E. Tooling - Cost and Availability 

NOTE: Because of the difficult access, Pilatus recommends that the maximum diameter of the 

measurement probe is 6,25 mm (0.25 in.).

PART No. DESCRIPTION QTY REMARKS

- EDDY-CURRENT EQUIPMENT 

WITH CONDUCTIVITY 

MEASUREMENT PROBE

1 Local supply

OR

- CONDUCTIVITY MEASUREMENT 

EQUIPMENT

1 Local supply

- BOROSCOPE 1 Local supply

- ALUMINIUM OR STEEL TUBE OF 

APPROXIMATELY 800 MM 

LENGTH X 10 MM DIAMETER

1 Local supply
Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 6 of 18

SERVICE BULLETIN

3. Accomplishment Instructions - On Aircraft

WARNING: READ AND OBEY THE MANUFACTURERS HEALTH INSTRUCTIONS BEFORE YOU 

USE THE CONSUMABLE MATERIALS.

A. Preparation

(1) Remove the access panel F5 (Ref. AMM, 12-00-00, Page Block 1).

(2) Remove the seat from the front cockpit (Ref. AMM, 25-10-00, Page Block 201).

(3) Obey the manufacturer’s operating instructions and calibrate the conductivity 

measurement equipment.

(4) Put the eddy current probe in position on the reference plates (P/N 513.57.09.149 and 

P/N 513.57.09.150).

(5) Record the value shown on the test equipment.

NOTE: The temperature of the left and right, upper and lower, engine mount fittings (P/N 

112.35.07.152) and the reference plates (P/N 513.57.09.149 and 

P/N 513.57.09.150) must be approximately the same.

B. Do the Test to Find the Material Specification (Ref. Fig. 1)

NOTE: Only personnel that are qualified and authorized by their delegated Airworthiness 

Authorities are allowed to do this test.

NOTE: Because of the access, Pilatus recommends that the conductivity probe has a 

maximum diameter of approximately 6.25 mm (0.25 in.).

(1) For the left upper engine-mount attachment-fitting (1) (P/N 112.35.07.152):

WARNING: BE CAREFUL WHEN YOU USE THE CONSUMABLE MATERIALS. OBEY 

THE MANUFACTURER‘S HEALTH AND SAFETY INSTRUCTIONS.

(a) Remove the dirt and grease from the test area with the absorbent paper (Material 

No. P02-031) made moist with the solvent (Material No. P01-010).

NOTE: It is not necessary to remove the layers of surface protection (including 

paint) to do the test.

NOTE: The temperature of the engine mount fittings (P/N 112.35.07.152) and the 

reference plates (P/N 513.57.09.149 and P/N 513.57.09.150) must be 

approximately the same.

(b) Put the eddy current probe in position on the left upper engine-mount attachmentfitting (1) (P/N 112.35.07.152).

(c) Record the value shown on the test equipment.

(d) Compare the value recorded above with the values recorded in Section 3.A.(5) and 

determine if the attachment fitting is manufactured from AA2024-T351 or AA2124-

T851.

(e) Do Steps 3.B(1)(b) thru (d) again to make sure the result is the same.
SERVICE BULLETIN

Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 7 of 18

(f) Write the type of material that the left upper engine-mount attachment-fitting (1) 

(P/N 112.35.07.152) is made from on the Status of Parts Form (Ref. Fig 5).

(2) Do Step 3.B.(1) of this Service Bulletin again on the right upper and left and right lower, 

engine mount fittings (P/N 112.35.07.152).

(3) If you find an engine mount fitting made from AA2024-T351, continue this Service Bulletin 

from Step 3.C.

(4) If all the engine mount fittings are made from AA2124-T851, continue this Service Bulletin 

from Step 3.D.

C. Do the Boroscope Inspection to Find Cracks (Ref. Fig. 2)

NOTE: Step 3.C. is only applicable to engine mount fittings made from AA2024-T351.

NOTE: Only personnel that are qualified and authorized by their delegated Airworthiness 

Authorities are allowed to do this test.

(1) Obey the manufacturer’s instructions and use a boroscope to examine the areas shown in 

Fig. 2:

(a) Use the aluminium or steel tube as a guide for the boroscope to access the 

inspection areas.

(b) If you find cracks:

1 You must contact Pilatus Customer Support before next flight. The address 

is:

PILATUS AIRCRAFT LTD.,

Customer Technical Support (MCC),

P.O. Box 992

6371 Stans, Switzerland

Fax: + 41 (0)41 619 67 73

Email: Techsupport@pilatus-aircraft.com

2 Make a report of the inspection results, refer Step 3.D.

(c) If you do not find cracks, make a report of the inspection results, refer Step 3.D.
Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 8 of 18

SERVICE BULLETIN

D. Report the Inspection Results

(1) Make a copy of the Inspection Report Form(s) (Ref. Fig. 3 and Fig. 4).

(2) Complete the Inspection Report Form(s):

• Give the date of the inspection.

• Give the aircraft details.

• Show the location(s) and dimensions of the crack(s) found (if applicable).

• Add any comments.

NOTE: If there are no crack indications, use the Inspection Report Form(s) to tell Pilatus 

Aircraft Ltd the aircraft details.

(3) Add the part number of the engine mount fittings to the final column of the Status of Parts 

Form (Ref. Fig. 5).

NOTE: If the engine mount fittings are made from AA2024-T351, the part number will be 

the same as that entered in column 3. If the engine mount fittings are made from 

AA2124-T851, the part number will change as shown in Para. 2.D.

(4) Send or fax the completed form(s) and a copy of the Status of Parts Form (Ref. Fig. 5) to 

Pilatus Customer Support.

E. Job Close-Up

(1) Remove all equipment, materials and tools from the work area. Make sure that the work 

area is clean.

(2) Install the seat in the front cockpit (Ref. AMM, 25-10-00, Page Block 201).

(3) Install the access panel F5 (Ref. AMM, 12-00-00, Page Block 1).

F. Documentation

(1) Make an entry in the Aircraft Logbook that this Service Bulletin has been incorporated.

(2) Use the Service Bulletin Evaluation Sheet and report your results and the serial number of 

the aircraft to Pilatus.

(3) Put the Status of Parts Form (Ref. Fig 5) in the Aircraft Logbook.

NOTE: If the engine mount fittings are made from AA2024-T351 but have no cracks, you 

will need to do repetitive inspections (Ref. AMM, Chapter 05). You will need this 

Form (Ref. Fig. 5) to tell you which engine mount fittings require the inspection.
SERVICE BULLETIN

Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 9 of 18

4. Accomplishment Instructions - Engine Mount Fittings Held as Spare or in Stock

NOTE: This procedure is applicable to all engine mount fittings (P/N 112.35.07.152) held as spare or 

in stock.

A. Preparation

(1) Obey the manufacturer’s operating instructions and calibrate the conductivity 

measurement equipment.

(2) Put the eddy current probe in position on the reference plates (P/N 513.57.09.149 and 

P/N 513.57.09.150).

(3) Record the value shown on the test equipment.

NOTE: The temperature of the engine mount fittings (P/N 112.35.07.152) and the 

reference plates (P/N 513.57.09.149 and P/N 513.57.09.150) must be 

approximately the same.

B. Do the Test to Find the Material Specification

NOTE: Only personnel that are qualified and authorized by their delegated Airworthiness 

Authorities are allowed to do this test.

(1) For each engine mount fitting (P/N 112.35.07.152):

WARNING: BE CAREFUL WHEN YOU USE THE CONSUMABLE MATERIALS. OBEY 

THE MANUFACTURER‘S HEALTH AND SAFETY INSTRUCTIONS.

(a) Remove the grease from the test area with the absorbent paper (Material No. 

P02-031) made moist with the solvent (Material No. P01-010).

NOTE: It is not necessary to remove the layers of surface protection (including 

paint) to do the test.

(b) Put the eddy current probe in position on the engine mount fitting (P/N 

112.35.07.152).

(c) Record the value shown on the test equipment.

(d) Compare the value recorded above with the values recorded in Section 4.A.(3) and 

determine if the engine mount fitting (P/N 112.35.07.152) is made from AA2024-

T351 or AA2124-T851.

(e) Do Steps 4.B(1)(b) thru (d) again to make sure the result is the same.

(f) If the engine mount fitting (P/N 112.35.07.152) is made from AA2024-T351, send it 

to Pilatus Customer Support. Pilatus will send a replacement engine mount fitting 

(P/N 553.10.07.032) made from AA2124-T851.

(g) If the engine mount fitting (P/N 112.35.07.152) is made from AA2124-T851, reidentify the fitting (Ref. Para. 2.D.) with a permanent marker pen (or equivalent).
Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 10 of 18

SERVICE BULLETIN

C. Job Close-Up

(1) Return the engine mount fittings to stores.

(2) Make sure the part number is correct and either P/N 553.10.07.033 (Re-identified) or P/N 

553.10.07.032 (New).

D. Documentation

(1) Make an entry on the serviceable label (attached to the engine mount fitting) that this 

Service Bulletin has been incorporated.

(2) Use the Service Bulletin Evaluation Sheet and report your results to Pilatus.
SERVICE BULLETIN

Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 11 of 18

 Check of the Material Specification

Figure 1

A

FRAME 1

A

FRAME 1

B

C

C

C

B

LH SHOWN

RH SIMILAR

1

LH SHOWN

RH SIMILAR

B

2

SB 2198
Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 12 of 18

SERVICE BULLETIN

 Fittings - Crack Inspection (If Necessary)

Figure 2

A

FRAME 1

A

FRAME 1

B

C

C

C

B

LH SHOWN

RH SIMILAR

LH SHOWN

RH SIMILAR

B

SB 2199

CRACK INSPECTION AREA

(INSPECT BOTH FLANGES)

CRACK INSPECTION AREA

(INSPECT BOTH FLANGES)
SERVICE BULLETIN

Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 13 of 18

 Upper Fittings - Inspection Form

Figure 3

SB 2200

RH UPPER FITTING

DATE: AIRCRAFT MSN: FLYING HOURS: LANDINGS:

CRACK 1 ADDITIONAL COMMENTS

LENGTH

mm

CRACK 2

LENGTH

CRACK 3

LENGTH

CRACK 4

LENGTH

mm

mm

mm

LH UPPER FITTING

DATE: AIRCRAFT MSN: FLYING HOURS: LANDINGS:

CRACK 1 ADDITIONAL COMMENTS

LENGTH

mm

CRACK 2

LENGTH

CRACK 3

LENGTH

CRACK 4

LENGTH

mm

mm

mm
Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 14 of 18

SERVICE BULLETIN

 Lower Fittings - Inspection Form

Figure 4

SB 2201

RH LOWER FITTING

DATE: AIRCRAFT MSN: FLYING HOURS: LANDINGS:

CRACK 1 ADDITIONAL COMMENTS

LENGTH

mm

CRACK 2

LENGTH

CRACK 3

LENGTH

CRACK 4

LENGTH

mm

mm

mm

LH LOWER FITTING

DATE: AIRCRAFT MSN: FLYING HOURS: LANDINGS:

CRACK 1 ADDITIONAL COMMENTS

LENGTH

mm

CRACK 2

LENGTH

CRACK 3

LENGTH

CRACK 4

LENGTH

mm

mm

mm
SERVICE BULLETIN

Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 15 of 18

 Status of Parts Form

Figure 5

Line No. Component Part Number Material Specification, after accomplishment of this Service Bulletin Part Number, after accomplishment of this Service Bulletin 

1 The engine upper-mount fitting, LH 112.35.07.152 2 The engine upper-mount fitting, RH 112.35.07.152 3 The engine lower-mount fitting, LH 112.35.07.152 4 The engine lower-mount fitting, RH 112.35.07.152 
Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 16 of 18

SERVICE BULLETIN

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SERVICE BULLETIN

Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 17 of 18

SERVICE BULLETIN EVALUATION SHEET FOR SB No. 53-008

Title

Fuselage - General - Do a Check of the Material Specification 

Used in the Manufacture of the Engine Mount Fittings and, If 

Necessary, Do a Check for Cracks with a Boroscope

Customer

Service Center

EMBODIMENT REPORTING

This SB has been embodied: On the entire fleet

Only partially

Provide embodiment details per aircraft (use additional copies of this table, if necessary)

MSN Flying Hours MSN Flying Hours

Additional embodiment comments/findings

EDITORIAL COMMENTS

 (procedure, kit quality, suggested improvements, etc.)

Name Signature Date

Please complete and forward this form to:

Pilatus Aircraft LTD,

Customer Technical Support (MCC),

P.O. BOX 992,

6371 Stans, Switzerland

Fax: +41 (0)41 619 6773

Email: Techsupport@pilatus-aircraft.com

SERVICE BULLETIN EVALUATION SHEET
Service Bulletin No: 53-008 Date: Nov 30/12

Rev. No. Date: Page 18 of 18

SERVICE BULLETIN

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