caravan service letter - altdi. · pdf filebulletin index locator 72-50-02 turboprop engine...

Caravan SERVICE LETTERCAL-71-09

TITLE

POWER PLANT - TRANSMITTAL OF P&WC S.B. NO. 1669R9

EFFECTIVITY

MODEL SERIAL NUMBERS

208 20800001 thru 20800505

208B 208B0001 thru 208B2090

REASON

The purpose of this service letter is to transmit Pratt & Whitney (P&WC) Service Bulletin P&WC S.B. No.1669R9, Turboprop Engine Compressor Turbine Blades - Inspection/Replacement Of.

DESCRIPTION

P&WC has issued P&WC S.B. No. 1669R9 to recommend the replacement of compressor turbine bladeson specified PT6A-114 and PT6A-114A Engines with blades of a new material.

On June 22, 2009, Cessna issued CAB09-5 to transmit SB1669R5.

Revision 9 changes the compliance recommendation of SB1669 to Category 3. To help preventcreep-related events, Revision 9 also introduces a borescope inspection for Pre-SB1669 blades, andeither a metallurgical evaluation of a sample of Pre-SB1669 blades or a new compressor turbine diskbalancing assembly that incorporates new turbine blades made from a different material.

COMPLIANCE

RECOMMENDED. This service letter should be accomplished at the next 200-hour or 12-month(annual-type) inspection.

MATERIAL AVAILABILITY

Refer to P&WC Service Bulletin S.B. No. 1669R9, Turboprop Engine Compressor Turbine Blades -Inspection/Replacement Of

REFERENCES

P&WC Service Bulletin S.B. No. 1669R9, Turboprop Engine Compressor Turbine Blades -Inspection/Replacement Of

P&WC Service Information Letter S.I.L. NO.PT6A-160 R1, Commercial Support Program for NewCompressor Turbine Blades

P&WC Service Information Letter S.I.L. NO. PT6A-116R3, Borescope Inspection in Conjunction withFuel Nozzle Check

ACCOMPLISHMENT INSTRUCTIONS

1. Refer to the attached P&WC Service Bulletin S.B. No. 1669R9 (or latest revision).

2. Make entries in the airplane and engine logbooks that state compliance and method of compliancewith this service letter.

CAL-71-09August 1, 2013 of 1

Cessna Aircraft Company, Cessna Customer Service, P.O. Box 7706, Wichita, KS 67277, U.S.A. 1-316-517-5800, Fax 1-316-517-7271

This document contains technical data and is subject to U.S. export regulations. This information has been exported from the United Statesin accordance with export administration regulations. Diversion contrary to U.S. law is prohibited. ECCN: 9E991

COPYRIGHT © 2013

Caravan OWNER ADVISORYCAL-71-09

TITLE

POWER PLANT - TRANSMITTAL OF P&WC S.B. NO. 1669R9

TO:

Cessna 208/208B Owner

REASON

This owner advisory is to inform you that CAL-71-09 has been issued.

The purpose of CAL-71-09 is to transmit Pratt & Whitney (P&WC) Service Bulletin P&WC S.B. No.1669R9, Turboprop Engine Compressor Turbine Blades - Inspection/Replacement Of.

DESCRIPTION

P&WC has issued P&WC S.B. No. 1669R9 to recommend the replacement of compressor turbine bladeson specified PT6A-114 and PT6A-114A Engines with blades of a new material.

On June 22, 2009, Cessna issued CAB09-5 to transmit SB1669R5.

Revision 9 changes the compliance recommendation of SB1669 to Category 3. To help preventcreep-related events, Revision 9 also introduces a borescope inspection for Pre-SB1669 blades, andeither a metallurgical evaluation of a sample of Pre-SB1669 blades or a new compressor turbine diskbalancing assembly that incorporates new turbine blades made from a different material.

COMPLIANCE

RECOMMENDED. This service letter should be accomplished at the next 200-hour or 12-month(annual-type) inspection.

LABOR HOURS

Refer to P&WC Service Bulletin S.B. No. 1669R9, Turboprop Engine Compressor Turbine Blades -Inspection/Replacement Of

WARRANTY

Refer to P&WC Service Bulletin S.B. No. 1669R9 (or latest revision) and P&WC Service InformationLetter S.I.L. NO. PT6A-160R1 (or latest revision).

Please contact a Cessna Caravan Authorized Service Facility for detailed information and arrange tohave Cessna service letter CAL-71-09 accomplished on your airplane.

NOTE: As a convenience, service documents are now available online to all our customers through asimple, free-of-charge registration process. If you would like to sign up, please visit the "CustomerSupport Login" link at www.Cessna.com to register.

CAL-71-09August 1, 2013 Page 1 of 1

Cessna Aircraft Company, Cessna Customer Service, P.O. Box 7706, Wichita, KS 67277, U.S.A. 1-316-517-5800, Fax 1-316-517-7271

This document contains technical data and is subject to U.S. export regulations. This information has been exported from the United Statesin accordance with export administration regulations. Diversion contrary to U.S. law is prohibited. ECCN: 9E991

COPYRIGHT © 2013

BULLETIN INDEX LOCATOR72-50-02

TURBOPROP ENGINECOMPRESSOR TURBINE BLADES - INSPECTION/REPLACEMENT OF

MODEL APPLICATION

PT6A-114, PT6A-114A

Commercial Support Program No: 1004551

Compliance: 3, 3, 3

Summary: There can be blade creep at the compressor turbine area when the engine isoperated at higher temperatures and power than the Pilot Operating Handbook (POH)recommended power settings.To prevent creep-related events, this service bulletin introduces:

v a borescope inspection for Pre-SB1669 blades.

v a metallurgical evaluation of a sample of Pre-SB1669 blades at HSI; or

v a new compressor turbine disk balancing assembly which incorporates redesignedturbine blades made from a different material.

PRATT & WHITNEY CANADA

SERVICE BULLETINP&WC S.B. No. 1669R9

Jul 22/2008 PT6A-72-1669Revision No. 9: Jun 28/2013 Cover Sheet

24-Hour Global Service USA & CANADA........................ 1-800-268-8000 Other .......................................... 1-450-647-8000

CFIRST CENTRE International .................... (IAC*)+8000-268-8000 Fax ............................................. 1-450-647-2888

Toll free where available (SIL GEN-027) * International Access Code Web Site .................................. www.pwc.ca

WARNING - PROPRIETARY RIGHTS & EXPORT CONTROLS NOTICE

This bulletin contains proprietary information of Pratt & Whitney Canada Corp. (″P&WC″), whichP&WC provides in confidence and solely for the purposes of supporting engine certification andproviding applicable information regarding the proper use, maintenance, inspection, repair, servicingand parts application of P&WC products and services, as directed therein. Neither this bulletin norany information in it may be disclosed to others, or used for any other purpose, including, withoutlimitation, to design, create, develop, reproduce, manufacture or derive any design, part, product,material, process, modification, configuration change or repair, or obtain FAA or other governmentapproval to do so. Possession and use of this bulletin is also subject to the restrictions set out inP&WC’s Technical Data Agreement (a copy of which may be obtained by contacting P&WC TechnicalPublications). The contents of this bulletin may be subject to export control laws. Unauthorized exportor re-export of the bulletin, or parts thereof, is prohibited. By accepting and possessing this bulletin,you agree to be bound by the foregoing terms.

If a Government agency or department intends to disclose any information, written notice should begiven to:VP - Legal Services, Pratt & Whitney Canada Corp., 1000 Marie-Victorin (01BE5), Longueuil,Quebec J4G 1A1.

Export Control Classification

*Data is subject to the jurisdiction of the Export and ImportControls Bureau of the Department of Foreign Affairs andInternational Trade of Canada, Department of Commerceof the United States and/or Department of State of theUnited States.

** Data is not subject to the jurisdiction of the Departmentof Commerce of the United States or Department of Stateof the United States but would become subject if exposedto any US involvement.

Regulation ClassificationNumber

Canadian ECL(s)*

ECCN(s)*

P-ECCN(s)** 9E991

USML (ITAR)*

P-USML**

REVISION TRANSMITTAL SHEETTURBOPROP ENGINE MODEL PT6A

SUBJECT: Pratt & Whitney Canada Service Bulletin No. PT6A-72-1669, Rev. No. 9, dated Jun28/2013 (P&WC S.B. No. 1669R9) COMPRESSOR TURBINE BLADES - INSPECTION/REPLACEMENT OF

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

Please retain this Revision Transmittal Sheet with the revised bulletin.

SUMMARY: This revision is issued to:

v add the Engine Serial Numbers in Para. 1.A., Effectivity.

v add CT Blade Trailing Edge Borescope inspection;

v add a two-CT blade sample for metallurgical evaluation at an overhaul facility.

v modify the compliance code to read 3.

v change the part replacement code from the disk to read 07 in lieu of 02.

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: Jul 22/2008Revision No. 1: Jul 25/2008Revision No. 2: Aug 15/2008Revision No. 3: Sep 08/2008Revision No. 4: May 05/2009Revision No. 5: Jun 11/2009Revision No. 6: Jul 14/2009

Revision No. 7: Jun 19/2012Revision No. 8: Jan 17/2013Revision No. 9: Jun 28/2013

Pratt & Whitney Canada Corp.1000, Marie-VictorinLongueuil, Québec, Canada J4G 1A1Tél. 450-677-9411

28 June 2013

P&WC S.B. No. 1669R9

1. Planning Information

A. Effectivity

PT6A-114 Engines which include Serial No. PCE-17001 thru PCE-17495.PT6A-114A Engines Serial No. which are before and include PC1611, PCE-19101 thru

PCE-19402 and excluding PCE-PC0463, PC0720, PC1266, PC1382, PC1476 andPC1563.

B. Concurrent Requirements

None.

C. Reason

(1) Problem

There can be blade creep at the Compressor Turbine (CT) area.

(2) Cause

The engine may have been operated at a higher temperature and higher powerthan the recommended power settings in the pilot operating handbook.

(3) Solution

Introduce an inspection and a metallurgical evaluation of Pre-SB1669 blades orincorporate a new CT disk balancing assembly which incorporates redesigned turbineblades made from a different material.

D. Description

This service bulletin is:

v (Part A) For engines not incorporating Part C, perform a borescope inspection of theCT blades trailing edge at each fuel nozzle inspection to a maximum of 400 Hrs.

v (Part B) For engines not incorporating Part C, submit a two-CT blade sample formetallurgical evaluation at an overhaul facility at HSI (Ref. P&WC SB No. 1703).

v (Part C) Replacing the CT disk balancing assembly or replacing the compressor turbineblades with new ones and re-identify the CT disk balancing assembly.

E. Compliance

For CT Blade Trailing Edge Borescope inspection of (Part A):

CATEGORY 3 - P&WC recommends to Inspect in conjunction with each fuel nozzleinspection, to a maximum of 400 hrs.

NOTE: Accomplishment of the borescope inspection is recommended within 150 Hrs ofissuance of this revision, if not conducted at previous nozzle inspection.

P&WC No. D9297J, D9297K, DCR5948, DCR5994, DCR6780, D9297R, DCR18946, E5427A,DCR21872, DCR22576, DCR23014



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

The export control classification with respect to this document is contained on the back of the locator.Jul 22/2008 PT6A-72-1669Revision No. 9: Jun 28/2013 Page 1 of 10© 2008 Pratt & Whitney Canada Corp.

PRINTED IN CANADA


1. Planning Information (Cont’d)

For engines at HSI (Part B):

CATEGORY 3 - P&WC recommends to submit a two-CT blade sample for metallurgicalevaluation at an overhaul facility (Ref. P&WC SB No. 1703).

For CT blades replacement of (Part C):

CATEGORY 3 - P&WC recommends to do this service bulletin when the engine isdisassembled and access is available to the necessary subassembly(i.e. module, accessories, components, or build groups). Do all sparesubassemblies, but not to exceed 36 months from the date of issueof this revision.

F. Approval

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

G. Manpower

For CT blades borescope inspection:

Once you have access to the part, an estimate of 4.0 man-hours is required to includethis service bulletin at maintenance.

For engines at HSI:


For CT blades replacement:


For Disk Balancing Assy-Compressor Turbine replacement:


H. Weight and Balance

None.

I. Electrical Load Data

Not changed.




The export control classification with respect to this document is contained on the back of the locator.Jul 22/2008 PT6A-72-1669Revision No. 9: Jun 28/2013 Page 2 of 10


1. Planning Information (Cont’d)

J. Software Accomplishment Summary

Not applicable.

K. References

Illustrated Parts Catalog P/N 3043514 (PT6A-114, PT6A-114A, PT6A-135, PT6A-135A)Maintenance Manual P/N 3043512 (PT6A-114, PT6A-114A, PT6A-135, PT6A-135A)Overhaul Manual P/N 3021243 (PT6A-34, PT6A-34AG, PT6A-34B, PT6A-35, PT6A-36,

PT6A-114, PT6A-114A, PT6A-135, PT6A-135A)P&WC S.B. No. 1703

L. Publications Affected

Illustrated Parts Catalog P/N 3043514 (PT6A-114, PT6A-114A, PT6A-135, PT6A-135A)

M. Interchangeability and Intermixability of Parts

Interchangeability - Refer to Para. 2.C.

Intermixability - Not intermixable, must be replaced as a complete set.

2. Material Information

A. Industry Support Information

Refer to Commercial Support Program Notification 1004551.

B. Material - Cost and Availability

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

The estimated total cost of new parts needed to replace old parts is $Quote (US, 2008).

The new parts are scheduled to be available in (June 2009).






C. Material Necessary for Each Engine

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

New P/N Keyword Old P/N Qty

Est. UnitList Price

($US,2008)

InstructionsDisposition

3072801-01 Disk Balancing Assy-Compressor Turbine

3045761-01 1 Quote (A)(B)

3072791-01 Ê Blade-Turbine 3045741-01 58 Quote (C)(D)

For post P&WC S.B. No. 1455 engines.


3102421-01 1 Quote (A)(B)

3072791-01 Ê Blade-Turbine 3039901 58 Quote (C)(D)

For pre P&WC S.B. No. 1521 engines.


3102421-01 1 Quote (A)(B)

3072791-01 Ê Blade-Turbine 3102401-01 58 Quote (C)(D)

(A) RESTRICTED INTERCHANGEABILITY - (ATA 200 Explanation Code 07):The old and the new part must be replaced by the new part.

(B) To get the new part it is possible to make a modification to the old part, or you can get thenew part from any Pratt & Whitney Canada Distribution Center.

(C) INTERCHANGEABLE AS A SET - (ATA 200 Explanation Code 06):When the replacement set is a single part number, the old and the new parts areinterchangeable in complete sets only.

(D) Subject to metallurgical evaluation, blades removed in compliance with Part B may bereplaced with the same Part Number prior to incorporation of Part C.

D. Reidentified Parts

The following list of parts can be reworked:

OLD P/N NEW P/N

3045761-01 3072801-013102421-01 3072801-01






E. Tooling - Price and Availability

Tool No. NomenclatureEst. Price

($US,) Delivery

PWC71903 Blade Stretch Quote

3. Accomplishment Instructions

A. For CT Blade Trailing Edge Borescope inspection of (Part A):

NOTE: This inspection is not required if the blades have been replaced withPost-SB1669 blades in accordance with Part C.

(1) Do the borescope inspection of the CT blades (Ref. MM 72-00-00. Table 601Borescope inspection).

(2) Write accomplishment of P&WC S.B. No. 1669 Part A in the applicable enginemodule log book.

TABLE 1, Compressor Turbine Blades Serial Numbers

Blade Position Serial No. Blade Position Serial No. Blade Position Serial No.

1 21 41

2 22 42

3 23 43

4 24 44

5 25 45

6 26 46

7 27 47

8 28 48

9 29 49

10 30 50

11 31 51

12 32 52

13 33 53

14 34 54

15 35 55






3. Accomplishment Instructions (Cont’d)

TABLE 1, Compressor Turbine Blades Serial Numbers (Cont’d)

Blade Position Serial No. Blade Position Serial No. Blade Position Serial No.

16 36 56

17 37 57

18 38 58

19 39

20 40

Engine Serial:

C.T. Disk S/N:

CT Blades P/N

B. For engines at HSI (Part B):

NOTE: This inspection is not required if the blades have been replaced withPost-SB1669 blades in accordance with Part C.

(1) Submit a two-CT blade sample for metallurgical evaluation at an overhaul facility(Ref. Pratt & Whitney Standard Practices Manual PN 585005) (Ref. P&WC SBNo. 1703).

(2) If the metallurgical evaluation is not acceptable, replace the complete set of CTblades with Post-SB1669 blades in accordance with Part C.

(3) Write accomplishment of P&WC S.B. No. 1669 Part B in the applicable enginemodule log book.

C. For the CT blades replacement of (Part C):

(1) Remove the CT Blades P/N 3039901 or P/N 3102401-01 or 3045741-01 anddiscard. Refer to the applicable maintenance or overhaul manual instructions.

(2) For the Disk Balancing Assy-Compressor Turbine reidentify as follows:







CAUTION: MAKE SURE THAT THE REMAINING ELECTROLYTE (ETCHSOLUTION) IS FULLY NEUTRAL AFTER YOU WRITE ON THEPART. ELECTROLYTE CAN CAUSE CORROSION ON THE PART.

(a) Put a line across the old part number. Use the electrolyte etch procedure,0.002 in. (0.05 mm) deep maximum, and write the new part number in thesame area.







(3) Implement conical grinding of the new CT blades per the applicable overhaulmanual instructions with the differences that follows:

(a) Incorporate 0°43’ taper (Ref Fig. 1).

(b) If necessary replace the segments to get the correct Fit and ClearanceNo. 318. Refer to the applicable maintenance or overhaul manual instructions.

(4) Install the parts listed under New P/N in Para. 2.C., Material Information. Refer tothe applicable maintenance or overhaul manual instructions.

NOTE: Record the CT Blades Serial Numbers (Ref. Table 1)

(5) Write accomplishment of P&WC S.B. No. 1669 Part C in the applicable enginemodule log book.

D. For Disk Balancing Assy-Compressor Turbine replacement:

(1) Remove the Disk Balancing Assy-Compressor Turbine in accordance with theMaintenance Manual or Overhaul Manual instructions.

(2) Write accomplishment of P&WC S.B. No. 1669 Part C in the applicable enginemodule log book.

4. Appendix

A. Refer to the Fits and Clearances Fig. No 2.

TABLE 2, CT Disk - Fits and Clearances No. 509

Dim. for Ref.inches (mm)

Limitsinches (mm)

REF.NO. IFR Name Min. Max. Min. Max. Replace

Post-SB1669509 Turbine Rotor Diameter

(Green Run) 8.526 8.536(216.56) (216.81)

509 Turbine Rotor Diameter(Overhaul) 8.496

(215.80)






DETAIL

A

A

0.0030.006

0 43’

0.050MAX.

TRAILINGEDGE

C145847

CT Blade Tip GrindingFigure 1






509

C145801

CT Disk - Fits and ClearancesFigure 2






EXPORT CONTROL CLASSIFICATION: This document does not contain technical data.ISSUED: Jun 16/ 2009

REVISED: Jul 03/ 2013 PRATT & WHITNEY CANADA CORP.MARIE-VICTORIN, LONGUEUIL

QUEBEC, CANADA J4G 1A1PRINTED IN CANADA

Page 1 of 2

S.I.L NO.PT6A-160 R1

SERVICE INFORMATION LETTER

Subject: Commercial Support Program for New Compressor Turbine Blades

Applicability: All PT6A-114 and –114A engines pre SB1669

Introduction:Pratt & Whitney Canada Corp. (P&WC) wishes to inform operators, maintainers andoverhaul shops of the release of a Commercial Support Program that provides asignificant discount when the new Compressor Turbine blade (CT Blade) is embodiedinto PT6A-114 and –114A engines per SB1669.

Reference:

CSPN No. CSPN 1004551SB1669 & SB1703Engine Maintenance Manual (EMM) and Overhaul Manual

Discussion:During the past 6 years P&WC has been informing operators of the impact on enginedurability and reliability caused by operation beyond the recommendations in the PilotOperating Handbook (POH). Operating the engine at higher temperatures and powerthan the POH recommended power settings can lead to accelerated compressorturbine blade creep potentially leading to CT blade distress.

P&WC has taken the initiative to design a new CT Blade that provides enhancedtolerance to creep while maintaining equivalent CT Disk life.

Additional advantages include:

1. Removal of the 5000 and 3000 hour inspection of the CT Blades and CT Disk forengines with the Post SB 1669 CT Blades

2. Increased creep allowance at overhaul

3. Exemption of the CT Blade trailing edge borescope inspection (via exhaust Duct)for engines Post SB 1669

4. Exemption of the hot section inspection (HSI) requirement to cut up two CTBlades.

SB1669 does not eliminate the requirement to perform borescope inspections of theHot section in conjunction with scheduled fuel nozzle inspections as defined in theEMM.

EXPORT CONTROL CLASSIFICATION: This document does not contain technical data.

ISSUED: Jun 16/ 2009 Page 2 of 2REVISED: Jul 03/ 2013

PRATT & WHITNEY CANADASERVICE INFORMATION LETTER

PWC: PT6A-160R1

P&WC is offering a onetime commercial support program for operators who wish torefresh their engines with the new CT Blades.

The program will provide operators with the opportunity to purchase the new CT Bladesat a significant price reduction.

1. If the operator elects to replace the blades at HSI or other repairs (excludingoverhaul) the price of the CT Blades will be at P&WC Price List less a discountof 70%.

2. When the CT blades are replaced at engine overhaul the price of the CT Bladeswill be P&WC Price List Less a discount of 60%.

The commercial support program offer will expire June 31, 2014.

P&WC advises operators to contact their shop representative at our P&WC ServiceCenters or at any of our P&WC Designated Overhaul Facilities to obtain additionaldetails on this commercial support program and to reserve a date for incorporation ofSB 1669.

Sincerely,

PRATT & WHITNEY CANADA CORP.

David MeiselsManager, Customer ProgramsCustomer Service

This Service Information Letter is valid until superceded or cancelled by revision.

S.I.L NO. PT6A-116R3

SERVICE INFORMATION LETTER

Subject: Borescope Inspection in Conjunction with Fuel Nozzle Check

Applicability: All PT6A Engine models

Reference: Engine Maintenance Manuals (EMM), (Section 72-00-00 Engine table 601,“Periodic Inspection” and Engine Inspection-Borescope CT Blades). P&WCService Information Letter (SIL) PT6A-125.

Reason for Revision:

Pratt & Whitney Canada Corp (PWC) has received feed back from operators concerning thenew borescope inspection procedure that allows inspection of the Compressor Turbine Bladetrailing edge.

Over the past 12 months Five (5) operators reported to P&WC that they were able to detectTrailing edge cracks on the Compressor Turbine Blades using this new procedure, by insertingthe fiberscope through the exhaust duct port and the power turbine stage. The new procedurewas introduced in the EMM in May 2006.

Despite P&WCs efforts to emphasize the importance of Borescope inspections, it has becomeevident during the investigation of recent Compressor Turbine (CT) Blade fracture events(which occurred in 2007) that not all operators are performing the recommended borescopeinspection at the same time as their scheduled fuel nozzle maintenance.

P&WC wished to remind operators that Borescope inspection is required per the EMM inconjunction with the fuel nozzle inspections as defined in the periodic inspection Table 601(Reference the EMM Section 72-00-00)

This requirement was introduced to help detect the presence of heat distress at the CT VaneRing. Pratt Whitney Canada Corp. (PWC) has determined that the loss of a part of a CT Vanetrailing edge as a result of heat distress may not necessarily result in a significant change tothe CT Vane flow class or overall efficiency of the vane assembly. Overall engine performancedeterioration may not be seen at regular ground power checks or during flight data collectionfor the ECTM plots.

.

EXPORT CONTROL CLASSIFICATION: This document does not contain technical data.ISSUED: Jan 24/ 2003

REVISED: Jul 03/ 2013 Page 1 of 6PRATT & WHITNEY CANADA CORP.

MARIE-VICTORIN, LONGUEUILQUEBEC, CANADA J4G 1A1

PRINTED IN CANADA

PWC:PT6A-116R3

EXPORT CONTROL CLASSIFICATION: This document does not contain technical data.ISSUED: Jan 24/ 2003 Page 2 of 6REVISED: Jul 03/ 2013

PRATT & WHITNEY CANADASERVICE INFORMATION LETTER

A hole in one vane of the CT Vane Ring trailing edges, in excess of the limits specified in theapplicable Maintenance Manual (MM), will change the exit flow velocity or angle at thatparticular vane window receives an impulse different from that of the other CT vane windows.Under such abnormal excitation, CT blade firtree fatigue may occur and the MM requiresreplacement of the entire set of CT Blades.

In addition to existing requirements, an inspection of the CT Blade trailing edge has beenintroduced for the PT6A-6 series engines (single power turbine). Please refer to EngineMaintenance Manual for applicability and accomplishment instructions reference table 601EMM section 72-00-00. For PT6A-114 &PT6A-114A Pre SB1669R9 Borescope inspection ofCT blade trailing edge via exhaust duct is to be conducted in conjunction with fuel nozzleinspection, to a maximum of 400 hrs. If not previously accomplished, carry out at next Aircraftminor inspection, not to exceed 150hrs.

In light of the possible consequences listed above, P&WC wishes to remind operators of theimportance of performing borescope inspection during fuel nozzle check as per the EMM. Foroperators who have not been complying to this requirement P&WC recommends that aborescope inspection be scheduled at their earliest convenience and that this practice beincorporated as part of their normal scheduled fuel nozzle maintenance.

Examples of the borescope inspections are shown in the following figures.

Fig. 1- View of CT Vane Ring and Blades

CT Vane RingLeading Edge

CT BladeLeading Edge

PWC: PT6A-116R3 PRATT & WHITNEY CANADASERVICE INFORMATION LETTER

EXPORT CONTROL CLASSIFICATION: This document does not contain technical data.ISSUED: Jan 24/ 2003REVISED: Jul 03 / 2013 Page 3 of 6

CT BladeLeading

Fig. 2- View of CT Vane Ring Trailing Edge

CT Vane RingBurnt TrailingEdge

Fig. 3– Exhaust Duct Port


EXPORT CONTROL CLASSIFICATION: This document does not contain technical data.ISSUED: Jan 24/ 2003REVISED: Jul 03/ 2013 Page 4 of 6

Fig. 4- Fiberscope inserted in exhaust duct port

Fig.5 – View of Fiberscope inserted between PT blades and distal tips clear of CT blades(For reference only Power Turbine Vane Ring missing)



Fig. 6 –Borescope View of the CT blades obtained through the exhaust duct port and thepower turbine stage showing a trailing edge crack



Fig. 7- Borescope view of unacceptable platform corrosion, extends more than 2/3of the platform height.

Fig. 8– Borescope view of unacceptable platform corrosion, blistering can beseen to extend forward of the trailing edge.

Yours truly,

David MeiselsManagerService Engineering, Customer SupportPRATT & WHITNEY CANADA CORP.

This Service Information Letter is valid until superceded or cancelled by revision.

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