PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42

BULLETIN INDEX LOCATOR

TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

MODEL APPLICATION
JT15D-1, JT15D-1A, JT15D-1B, JT15D-4, JT15D-4B, JT15D-4D, JT15D-4C, JT15D-5, JT15D-5A,
JT15D-5C, JT15D-5D, JT15D-5F, JT15D-5R

Compliance: Refer to Para. 1.E. in the Service Bulletin

Summary: Standardize all JT15D engine models Time Between Overhaul (TBO) and Hot Section
Inspection (HSI) escalation process.

Dec 01/1973 JT15D-72-7003

Revision No. 42: Nov 07/2022 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
P&WC provides in confidence and solely for the purposes of supporting engine certification and
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
limitation, to design, create, develop, reproduce, manufacture or derive any design, part, product,
material, process, modification, configuration change or repair, or obtain FAA or other government
approval to do so. Possession and use of this bulletin is also subject to the restrictions set out in
P&WC’s Technical Data Agreement (a copy of which may be obtained by contacting P&WC Technical
Publications). The contents of this bulletin may be subject to export control laws. Unauthorized export
or 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 be
given to:
VP - Legal Services, Pratt & Whitney Canada Corp., 1000 Marie-Victorin (01BE5), Longueuil,
Quebec J4G 1A1.

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

07 November 2022

P&WC S.B. No. 7003R42

REVISION TRANSMITTAL SHEET

TURBOFAN ENGINE MODEL JT15D

SUBJECT: Pratt & Whitney Canada Service Bulletin No. JT15D-72-7003, Rev. No. 42, dated Nov
07/2022 (P&WC S.B. No. 7003R42) ENGINE OPERATING TIME BETWEEN
OVERHAULS AND HOT SECTION INSPECTION FREQUENCY

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 Para. 1.K., References to add SB 7151; and

v update Para. 3.H. Accomplishment Instructions to correct the table reference to
Table 3 in the paragraph and to add SB 7151 to Table 3, Service Bulletins.

NOTE: Only changes to the technical content have a black bar in the margin

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: Dec 01/1973 Revision No. 8: Jun 22/1979 Revision No. 16: Aug 16/1985
Revision No. 1: Apr 08/1973 Revision No. 9: Oct 06/1980 Revision No. 17: Sep 04/1985
Revision No. 2: Jul 02/1974 Revision No. 10: Jan 26/1982 Revision No. 18: Dec 02/1985
Revision No. 3: Jul 07/1975 Revision No. 11: Sep 02/1982 Revision No. 19: Feb 10/1989
Revision No. 4: Nov 23/1976 Revision No. 12: Oct 25/1982 Revision No. 20: Oct 06/1989
Revision No. 5: Apr 22/1977 Revision No. 13: Oct 19/1983 Revision No. 21: Jan 30/1991
Revision No. 6: Aug 10/1978 Revision No. 14: Feb 20/1984 Revision No. 22: Dec 04/1991
Revision No. 7: Apr 06/1979 Revision No. 15: Oct 25/1984 Revision No. 23: Sep 22/1992

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 Pratt & Whitney Canada Corp.

Revision No. 24: Never Issued

Revision No. 25: Jul 07/1993
Revision No. 26: Dec 22/1993
Revision No. 27: Apr 26/1994
Revision No. 28: Oct 31/1994
Revision No. 29: Apr 08/1999
Revision No. 30: Oct 04/1999
Revision No. 31: Jan 10/2001
Revision No. 32: Oct 08/2002
Revision No. 33: Oct 27/2006
Revision No. 34: Jul 08/2009
Revision No. 35: Jun 02/2011
Revision No. 36: Feb 18/2013
Revision No. 37: Mar 18/2014
Revision No. 38: Sep 09/2014
Revision No. 39: Apr 01/2016
Revision No. 40: Dec 16/2016
Revision No. 41: Dec 17/2020
Revision No. 42: Nov 07/2022

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

1. Planning Information

A. Effectivity
JT15D-1, JT15D-1A, JT15D-1B, JT15D-4, JT15D-4B, JT15D-4D, JT15D-4C, JT15D-5,
JT15D-5A, JT15D-5C, JT15D-5D, JT15D-5F and JT15D-5R Engines.

B. Concurrent Requirements

None.

C. Reason

To provide recommended operating time between overhauls and to recommend initial

Hot Section Inspection (HSI) frequency.

D. Description

(1) Time Between Overhaul recommendations take into consideration the average
effect of the many variables affecting overhaul life, such as average flight
duration, percentage of time at any given power level, climatic conditions and
environment, maintenance practices, utilization and engine modification standards.

(2) Under extreme conditions of very low utilization, coupled with continuous operation
in salt water atmosphere or heavy sand or dust environment, periodic inspections in
accordance with the applicable maintenance instructions may indicate
maintenance action prior to the recommended overhaul life.

E. Compliance

The inspection intervals and overhaul periods provided in this bulletin are the
manufacturer’s recommendations. Airworthiness authorities normally require operators to
follow these recommendations unless alternative arrangements have been made
between the operator and the manufacturer, and approved by the operator’s airworthiness
authority.

F. Approval

Transport Canada has reviewed and approved the technical contents of this Service
Bulletin.

NOTE: The service life values quoted herein are determined by the limiting values
stated on the Pratt & Whitney Canada drawings which form part of the
Department of Transport Aircraft Engine Type Approval for the applicable
engine model. These limiting values are based on the use of P&WC supplied
parts installed on/in the engine. Use of other than P&WC supplied components
may reduce the life limits.

P&WC No. NA, DCR26445, DCR27329, DCR37347, EC-0007163, EC-0017440

Dec 01/1973 P&WC Proprietary Information. Subject to the restrictions on the back of the locator JT15D-72-7003
Revision No. 42: Nov 07/2022 © 1973 Pratt & Whitney Canada Corp. Page 1 of 12
PRINTED IN CANADA

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

1. Planning Information (Cont’d)

G. Manpower

Not applicable.

H. Weight and Balance

None.

I. Electrical Load Data

Not changed.

J. Software Accomplishment Summary

Not applicable.

K. References
Applicable Technical Manuals (
P&WC S.B. No. JT15D-72-7002, -7074, -7115, -7123, -7151, -7189, -7216, -7249 and
-7275

L. Publications Affected
Applicable Technical Manuals

M. Interchangeability and Intermixability of Parts

Not applicable.

2. Material Information

A. Industry Support Information

Not applicable.

B. Material - Cost and Availability

Not applicable.

C. Material Necessary for Each Engine

Not applicable.

D. Reidentified Parts

None.

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

2. Material Information (Cont’d)

E. Tooling - Price and Availability

Not applicable.
3. Accomplishment Instructions

A. Time Between Overhaul (TBO) Recommendations:

NOTE: 1. ± 50 hours is allowed for scheduling purposes. Life limited High Pressure
Turbine blades take precedent over the scheduled TBO interval. LCF
SBJT15D-72-7002 takes precedent over TBO intervals stated in SBJT15D-72
-7003.

NOTE: 2. The requirements of SB7002 are to be respected notwithstanding the

provisions of this service bulletin.

TABLE 1, TBO/HSI RECOMMENDATION

SB TBO
Incorporated Approved HSI Approved
Models TBO Basic HSI Basic (See Note) (See Note) (See Note)

JT15D-1 1800 900 7074 2400 1200

7074 3500 1750
and 7115

JT15D-1A 1800 900 7074 2400 1200

7074 3500 1750
and 7115
JT15D-1B 3000 1500

JT15D-4 2400 1200 7115 3500 1750

JT15D-4B 2400 1200 7189 and/or 3500 1750

7275
7189 and/or 3000 1500
7275
and 7216

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

3. Accomplishment Instructions (Cont’d)

TABLE 1, TBO/HSI RECOMMENDATION (Cont’d)

SB TBO
Incorporated Approved HSI Approved
Models TBO Basic HSI Basic (See Note) (See Note) (See Note)

JT15D-4C 1500 750

JT15D-4D 2400 1200 7189 3500 1750

JT15D-5 1500 750 7249 3600 1800

JT15D-5A 3500 1750

JT15D-5C 2500 1250

JT15D-5D 3500 1750

JT15D-5F 3000 1500

JT15D-5R 3600 1800

NOTE: ‘‘TBO Approved’’ and ‘‘HSI Approved’’ refers to the TBO and HSI
interval for the corresponding model, provided the service bulletin
listed under ‘‘SB Incorporated’’ has been incorporated. For example,
a JT15D-1 engine which has incorporated SB 7074 has a TBO of
2400 hours and a HSI interval of 1200 hours. The TBO and HSI
interval for a JT15D-1 engine which has not incorporated SB7074
would be found under ‘‘TBO Basic’’ (1800 hours) and HSI Basic (900
hours).

(1) Operators desiring a technical recommendation for TBO or HSI extension should
submit a formal request in writing to P&WC Technical Support at the address
below.

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

3. Accomplishment Instructions (Cont’d)

(2) All operators of JT15D engines may increase their fleet TBO by 500 hours,
following satisfactory exhibit of engine samples of the given engine model at the
respective TBO interval specified above or at the prevailing level, if fleet TBO
has already been increased by this process. It may be required prior to access to
the next TBO level to incorporate minimum Service Bulletins listed as recommended
by Pratt & Whitney Canada.
(3) If P&WC comments on engine condition are required, please provide sample plan
and specific timing to the following address at least one month prior to induction
into our service center:
Pratt & Whitney Canada
Atten: Manager, Technical Support
JT15D Engines
1000 Marie-Victorin
Longueuil, Quebec
Canada J4G 1A1
(4) Para. 3.A. (3), does not apply to JT15D -1 operators whose engines qualify for
1800 hour maximum TBO. In this case, the 1800 hours interval is binding.
B. Engine accessories are to be processed in accordance with the following instruction.
The definitions of engine/module soft and hard time are as follows:
(1) Hard-time: The engine/module hard-time is defined as the Transport Canada
approved maximum threshold interval between overhaul of engine/modules for
those operators who do not:
(a) Maintain the engine in accordance with an approved on-condition program
or
(b) Have an escalation program approved for their fleets by the local authority.
(2) Soft-time: The engine/module soft-time is defined as an economic minimum interval
before complete restoration of engine/modules is recommended for those operators
maintaining the engine in accordance with an approved on-condition program.
When a module reaches the declared soft-time it need not be removed from the
aircraft. When the engine is removed from the aircraft and the engine/module has
passed the soft-time, it is considered economically beneficial to restore the
engine/module.
C. The following Accessories or Line Replacement Unit (LRU) installed on JTI5D engines
are to be visually inspected (Ref. Engine Maintenance Manual (EMM)), at every minor
aircraft inspection interval (Ref. Airframe Maintenance Manual (AMM)). Accessories that
are not listed below are to be inspected in accordance with CMM concurrent with
engine overhaul +/- 500 hrs.

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

3. Accomplishment Instructions (Cont’d)

v Ignition Exciter.
v Bleed Valve Actuator (D5 Series).
v Schedule Modulator (Applicable only for JT15D-1A and JT15D-4, refer to SB7124).
v Main Wiring Harness (JT15D-5 series, JT15D-4C).
v T1 Thermocouple Wiring Harness.
v Electronic Bleed Valve Control/Electronic Engine Control (D5 Series and the 4C).
v Fuel Temperature Indicator (Applicable only for JT15D-5R).

NOTE: At engine overhaul the accessories listed above require a visual

inspection and a functional check during the engine pass-off test.
They need not be overhauled or repaired unless the component has
failed visual inspection or functional check at test.
D. Except for the following accessories which are subject to a soft-time inspection.

v Flow Divider Valve

v Motive Flow Valve
v Oil Cooler
E. Accessories soft-time inspections (Ref. Table 2).
(1) Soft time inspections recommended in this table are based on known historical
reliability data evaluated by P&WC. These inspections are subject to specific
recommendations. Use one of the two alternate options (A or B) when an engine is
sent to a P&WC Overhaul Facility or P&WC Designated Overhaul Facility
(D.O.F) or when an accessory is at an approved accessory shop which can perform
specific Component Maintenance Manual (CMM) and Temporary Revisions (TR)
inspections.
(2) If as received inspection of the accessory is found out of tolerance or the removal
reason is directly related to the component, it is recommended to overhaul or
refurbish the accessory.
F. Here are the definitions of each option which can be selected by operators when
selecting the tracking methodology for accessories.
(1) Option A:
The option A is defined for accessories with a known time being currently recorded
by operators. This option requires keeping record of the data listed below. For
operators who wish to use this option but do not have these records, P&WC
recommends to start with the option B and then revert to the option A.

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

3. Accomplishment Instructions (Cont’d)

(a) The tracking of one of the following time is to be used when selecting the
option A :

v Part Number & Serial Number

v Time since new (TSN)
v Time since inspection (TSI) or Time Since Repair (TSR)
v Time since overhaul (TSO)

(b) For accessories with recorded TSN, TSI/TSR or TSO running times, the
inspection is to be accomplished when the engine is sent for a shop visit and the
installed accessory has passed the soft-time defined in Table 2. Accessories
installed on engines are to be shipped with the engine for indicated
recommended inspection.

(c) The workscope for engine sent to the shop should specify the appropriate
inspection requirements for the accessories in line with Table 2.

(2) Option B:
The options B is defined for accessories where there is no known recorded TSN,
TSI/TSR or TSO running times and that operator elects not to track and record the
data.

(a) For accessories without recorded data running times, the recommended
inspections are to be performed at the same time as the Engine Overhaul.

(b) Accessories installed on engines sent to a scheduled shop visit are to be

shipped with the engine for indicated recommended inspection. The
workscope for engine sent to the shop should specify the appropriate inspection
requirements for the accessories as indicated in Table 2.

(c) The workscope for engine sent to the shop should specify the appropriate
inspection requirements for the accessories as indicated in Table 2.

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

3. Accomplishment Instructions (Cont’d)

TABLE 2, Inspection Requirements

Option A Option B
(TSI/TSN/TSO (TSI/TSN/TSO not
recorded by recorded by
Accessory Inspection operators) operators)

Flow Divider Valve Inspect and recertify At next engine visit At next engine
as per latest (unit has TSN/TSO overhaul
published CMM above 6,000 FH)
Motive Flow Valve Inspect and recertify At next engine visit At next engine
as per latest (unit has TSN/TSO overhaul
published CMM above 10,000 FH)
Oil Cooler Inspect and recertify At next engine visit At next engine
as per latest (unit has TSN/TSO overhaul
published CMM above 6,000 FH)

G. Hard Time Hot Section Inspection (HSI) Frequency Recommendations:

(1) For all engines operating to a scheduled HSI program, Pratt & Whitney recommends
that the HSI be performed within plus or minus 50 hours of schedule. This HSI
schedule is set at intervals not exceeding half the TBO interval (see Table 1) unless
separately recommended in writing by the Chief Engineer, Customer Support,
P&WC and approved by the local regulatory authority.

H. TBO extension recommendation:

For JT15D-1 Engine Series that have reached currently published overhaul TBO
intervals of 3000 hrs for JT15D-1B and 3500 hrs for JT15D-1 and JT15D-1A, can continue
operation upon completion of the TBO extension workscope for 1000 flight-hours +/−
50 flight-hours provided the following criteria are met:

(1) Prior to engine removal;

(a) Perform a boroscope inspection of the compressor section and the hot section
in accordance with the maintenance manual (Ref. 72-00-00 BOROSCOPE
INSPECTION).

(b) Perform an engine ground run performance check in accordance with the
maintenance manual (Ref. 71-00-00 POWER PLANT - ADJUSTMENT
TEST).

(c) Provide a Spectrometric Oil Analysis Program (SOAP) sample in accordance

with the maintenance manual (Ref. 79-20-01 OIL FILTER ELEMENT AND
HOUSING MAINTENANCE PRACTICES).

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

3. Accomplishment Instructions (Cont’d)

(2) The TBO extension workscope, as defined in the JT15D-1/4 overhaul manual (Ref.
P/N 3017543, Section 72-00-00 - TBO EXTENSION), is to be accomplished at an
approved overhaul facility.

(3) The following Service Bulletins in Table 3 are incorporated.

TABLE 3, Service Bulletins

For JT15D-1 Engine Model

SB7049 SB7069 SB7087 SB7115 SB7151 SB7190

SB7257 SB7269 or SB7288 SB7309 SB7317 or SB7384 or
SB7152 or SB7297 SB7306
SB7258
SB7541 SB7590 SB7604 SB7618 SB7620

(4) The rotor components service life specified in SB7002 are not exceeded.

NOTE: The requirements of SB7002 are to be respected notwithstanding the

provisions of this service bulletin.

(5) No core-related unscheduled maintenance event has occurred since previous

overhaul.

NOTE: At the end of the 1000 flight-hours interval that follows the TBO
extension workscope, the engine shall undergo a complete overhaul
in accordance with the JT15D-1/4 Overhaul Manual (Ref. 3017543)
prior to return to service.

I. Transferred from SB7002:

High turbine blades P/N 3029601 (Pre-SB7589) or P/N 3055021-01 (Post-SB7589) or
P/N 3070381-01 (Post-SB7604) are serviceable to the value of the figure stamped on the
blade root plus 0.006 inch.

NOTE: To permit full utilization of the blade life potential by changing replacement
criteria from a straight ‘‘hour count’’ to a creep growth acceptance limit.

J. High turbine blades must be replaced at or before the following specified limits:

Part Number Model Life Limit Hours

3019001 (Pre-SB7102) JT15D-1, -4 1,800
3028001 (Post-SB7102) JT15D-1, -1A, -4 2,400
3028601 (Post-SB7123) JT15D-1B 3,000

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

3. Accomplishment Instructions (Cont’d)

Part Number Model Life Limit Hours

3028601 (Post-SB7123) JT15D-1, -1A, -4 3,500
3028601 (Post-SB7123) JT15D-4B 1,800
3028601 (Post-SB7123) JT15D-4D 1,500
3029801 (Pre-SB7123) JT15D-4 2,400
3055011-01 JT15D-1B 3,000
3055011-01 JT15D-1, -1A 3,500

NOTE: Engines incorporating High Pressure Turbine (HPT) blades listed above,
may not apply for a Time Between Overhaul (TBO) or Hot Section
Inspection (HSI) extension.

K. High turbine blades installed successfully in various models of JT15D engines, and run
in engines modified to a different model, should have their remaining life calculated as
follows:

Model No. 1 Time Model No. 2 Time

Used Life Ratio = [ 1 - ( + ) ]
Model No.1 Life Limit Hours Model No.2 Life Limit Hours
L.

EXAMPLE:
Blade Part No. 3028601
Model No.1 (JT15D-1B) Time 1200 hrs.
Life Limit Hours 3000 hrs.
Model No.2 (JT15D-4B) Time 400 hrs.
Life Limit Hours 1800 hrs
Actual Model (JT15D-4D) Life Limited Hours 1500 hrs.

1200 400
Used Life Ratio = [ 1 - ( + ) ]
3000 1800
= [1 - (0.4 + 0.2222)]
= 0.3778

M. Remaining Life = Actual Model Life Limit x Used Life Ratio

=1500 x 0.3778
=566.7 hours on JT15D-4D engine.

N. Transfer of TBO Extension Recommendation:

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 PRATT & WHITNEY CANADA

SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

3. Accomplishment Instructions (Cont’d)

(1) TBO extensions by either the fleet extension or the engine specific method are
valid only as long as the operator, the Maintenance Organization (M.O.), and the
typical mission remain unchanged. The following conditions apply for P&WC to
transfer the recommendation to a new M.O., a new operator or a new application
(typical mission): two options available.

NOTE: For changes limited to the selection by the operator of a new M.O., the
change will have no effect if the maintenance plan remains unchanged
and the newly selected M.O. is already supporting operators who have
approval for the engines covered by this SB and to the same or higher
TBO.

(a) Option 1:
For transfers involving engines already operating under a fleet TBO extension,
or to be used in an operation with fleet TBO extension, P&WC uses a
pro-rating formula. This formula is generally recognized by regulatory authorities.
The TBO applicable to an engine under these circumstances is the average
of the fleet TBO formerly applicable and the fleet TBO separately established for
the new combination of operator, M.O. and the mission for the same engine
models. It is then weighted on the basis of the time remaining to overhaul under
the original operation. The formula for this purpose is:
X=Y * a/b
Where:

v X= time remaining to overhaul on new program (buyer’s TBO).

v Y=time remaining to overhaul on previous program (seller’s TBO)
v a=TBO interval on new program (buyer’s TBO)
v b=TBO interval on previous program (seller’s TBO)

1 Example:
An aircraft is transferred (by sale or lease) between two operators. The
previous operator’s TBO is 4500 hours and the new operator’s TBO is 3000
hours and the engine has a time since overhaul (TSO) of 4000 hours,
then:

v Time remaining to overhaul on the previous program is Y=4500-4000=500

hours

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SERVICE BULLETIN
P&WC S.B. No. 7003R42
TURBOFAN ENGINE
ENGINE OPERATING TIME BETWEEN OVERHAULS AND HOT SECTION INSPECTION
FREQUENCY

3. Accomplishment Instructions (Cont’d)

v Time remaining to overhaul on the new program is X=Y * a/b

ie:
X=500 * 3000/4500=333 hours
Based on the above formula the new owner having a lower engine TBO
(3000 hours) would have the engine inducted for overhaul upon reaching
4333 hours (TSO). Consecutive overhaul shop visits would be at 3000
TBO.

(b) Option 2:
For changes on an engine registered under the P&WC engine-specific TBO
extension program, the operator/owner can apply to P&WC for a transfer. If the
extension, its mission and its M.O. are already established as eligible for the
engine models per this service bulletin, no further action will be required.
Otherwise, it is necessary to establish the eligibility of the new operator,
application and/or M.O. before the recommendation can be extended to these
new conditions.

4. Appendix

Not applicable.

Dec 01/1973 P&WC Proprietary Information. Subject to the restrictions on the back of the locator JT15D-72-7003
Revision No. 42: Nov 07/2022 Page 12 of 12

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