APU Power Plant Borescope Inspection (131-9(A))

TASK 49-20-00-200-003-A
APU Power Plant Borescope Inspection (131-9(A))

WARNING: DO NOT TOUCH THE APU UNTIL IT IS SUFFICIENTLY COOL TO PREVENT BURNS WHEN YOU DO THE MAINTENANCE TASK(S).

WARNING: DISCONNECT THE LOW-TENSION ELECTRICAL SUPPLY 6 MINUTES BEFORE YOU START WORK ON THE IGNITION SYSTEM. THE HIGH CURRENT AND VOLTAGE WHICH ARE USED IN THE IGNITION SYSTEM CAN KILL YOU.

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

ZONE: 400
FIN: 4005KM ** ON A/C NOT FOR ALL

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE
No specific	1	EXTENSION LENGHT 6 IN (152,4 MM)
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	1	SOCKET DIA 5/16 IN - HEXAGONAL
No specific	Torque wrench: range to between 0.627 and 0.513 m.daN (55.49 and 45.40 lbf.in )
No specific	Torque wrench: range to between 0.99 and 0.81 m.daN (87.61 and 71.68 lbf.in )

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.03BEB1)	Mineral base Lubricating Oil-Turbine Engine - -
(Material No.14QEB1)	Wire-Locking Dia: 0.6 mm CRES Nickel Alloy -

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
400	POWER PLANT, NACELLES AND PYLONS
315AL, 316AR

D. Expendable Parts

FIG.ITEM	DESIGNATION	IPC-CSN
2	PACKING	AIPC 49-23-09-01-160
2	PACKING	AIPC 49-23-84-30-140

E. Referenced Information

REFERENCE	DESIGNATION
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 24-42-00-862-001-A	De-energize the Ground Service Network Supplied from the External Power
TASK 29-00-00-864-001-A	Put the Related Hydraulic System in the Depressurized Configuration before Maintenance Action
TASK 29-14-00-614-002-A	Pressurization of the Hydraulic Reservoirs through the Ground Connector
TASK 29-14-00-614-002-A-01	Pressurization of the Hydraulic Reservoirs with the Auxiliary Power Unit (APU)
TASK 49-00-00-790-003-A	Leak Test of the APU
TASK 49-00-00-860-008-A	APU Start by External Power
TASK 49-00-00-860-008-A-01	APU Start by Batteries
TASK 49-00-00-860-009-A	APU Shutdown by External Power (131-9(A))
TASK 49-00-00-860-009-A-01	APU Shutdown by Batteries (131-9(A))
TASK 49-00-00-970-001-A	Access to the Data Memory Module (DMM) Report (131-9(A))
TASK 49-23-51-000-004-A	Removal of the Inlet Guide Vane - Actuator (131-9(A))
TASK 49-23-51-400-004-A	Installation of the Inlet Guide Vane - Actuator (131-9(A))
TASK 49-41-41-000-005-A	Removal of the Igniter Plug (131-9(A))
TASK 49-41-41-400-004-A	Installation of the Igniter Plug (131-9(A))
TASK 49-72-15-000-002-A	Removal of the Thermocouples (131-9(A))
TASK 49-72-15-400-003-A	Installation of the Thermocouples (131-9(A))
TASK 52-41-00-010-001-A	Open the APU Doors for Access
TASK 52-41-00-410-001-A	Close the APU Doors after Access
TSM 49-00-81-810-835	APU AUTO SHUTDOWN - NO ACCELERATION, Fuel-Control Unit Fault (131-9(A))
Borescope Examination
Load-Compressor Diffuser Damage-Criteria
Load-Compressor Trailing-Edge Damage Criteria ** ON A/C NOT FOR ALL
Load-Compressor Trailing-Edge Damage Criteria ** ON A/C NOT FOR ALL
Clevis Assembly and Attaching Bolt
Inlet Guide Vane (IGV) Damge Criteria (IGV closed)
Inlet Guide Vane (IGV) Damage Criteria (IGV open)
Load-Compressor Impeller Leading-Edge-Damage Conditions
Engine Compressor-Impeller Damage Criteria
Compressor-Diffuser Damage Criteria
Combustor Damage Criteria
Combustion Chamber
First Stage Turbine-Nozzle Assy Damage Criteria
First Stage Turbine-Blade Damage Criteria
Second Stage Turbine-Blade Damage Criteria

3. Job Set-up
Subtask 49-20-00-860-079-A ** ON A/C NOT FOR ALL

A. Aircraft Maintenance Configuration
(1) On panel 25VU, make sure that the APU MASTER SW p/bsw is off.
(2) Put the warning notices on panel 25VU to tell persons not to start the APU.
(3) Energize the ground service network
(Ref. AMM TASK 24-42-00-861-001).
(4) Make sure that the hydraulic systems are depressurized
(Ref. AMM TASK 29-00-00-864-001).

Subtask 49-20-00-865-088-A ** ON A/C NOT FOR ALL

B. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	APU/APU/CTL	2KD	L42
121VU	APU/ECB/SPLY	1KD	L41

Subtask 49-20-00-010-068-A ** ON A/C NOT FOR ALL

C. Get Access
(1) Put the ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE in position below the APU compartment.
(2) Open the APU access doors 315AL 316AR (Ref. AMM TASK 52-41-00-010-001).
(3) Set the LIGHT control switch 11LJ to the ON position.

4. Procedure
Subtask 49-20-00-960-053-A ** ON A/C NOT FOR ALL

A. Examine the Load Compressor Diffuser for Damage

WARNING: USE PROTECTIVE GOGGLES AND GLOVES WHEN YOU REMOVE OR INSTALL LOCKWIRE. EACH TIME YOU CUT LOCKWIRE, REMOVE AND DISCARD IT IMMEDIATELY. LOOSE LOCKWIRE CAN CUT YOU OR MAKE YOU BLIND, AND/OR CAN CAUSE DAMAGE.

(1) Remove lockwire and plug (1) with packing (2) from the load compressor borescope port.
(2) Remove and discard packing (2).

CAUTION: MAKE SURE THE APU INTERNAL TEMPERATURE IS NOT MORE THAN 80 DEG.C (176 DEG.F) BEFORE YOU PUT THE BORESCOPE INTO THE APU. HEAT CAN CAUSE DAMAGE TO THE BORESCOPE.

(3) Push the optic fiber through dedicated borescope port on scroll, proceed past the trailing edge of the diffuser and examine the load compressor diffuser vanes.
(4) The load compressor diffuser vanes should be checked for impact damage.

Load-Compressor Diffuser Damage-Criteria ** ON A/C NOT FOR ALL

(a) The following observations are acceptable:
1 Leading edge nicks and rough edges due to erosion are acceptable without significantly displaced material (1).
2 Discoloration of vanes is acceptable.
3 Cracks found in the braze fillet area are acceptable (2).
(b) The following observations are not acceptable, the observations are criteria for APU removal:
1 Bucket shaped erosion is not acceptable (3).

Subtask 49-20-00-960-054-A ** ON A/C NOT FOR ALL

B. Examine the Load Compressor Impeller Trailing Edge for Damage
(1) Prepare to turn rotating group to examine the load compressor impeller:
(a) Remove cap from the end of the starter.
(b) Insert a SOCKET DIA 5/16 IN - HEXAGONAL, with attached 6 inch extension and ratchet wrench, onto the 5/16 inch hex shaft on the end of the starter.

CAUTION: MAKE SURE THE APU INTERNAL TEMPERATURE IS NOT MORE THAN 80 DEG.C (176 DEG.F) BEFORE YOU PUT THE BORESCOPE INTO THE APU. HEAT CAN CAUSE DAMAGE TO THE BORESCOPE.

CAUTION: BEFORE YOU ROTATE THE APU, MAKE SURE THAT THE BORESCOPE IS NOT IN THE RANGE OF THE COMPRESSOR IMPELLER BLADES. THE ROTATION OF THE BLADES CAN CAUSE DAMAGE TO THE BORESCOPE.

(2) Push the optic fiber through dedicated borescope port on scroll, proceed between two load compressor diffuser vanes, to view the edge of the impeller blades.
(3) Turn the rotating group as necessary and examine the load compressor impeller trailing edges.

Load-Compressor Trailing-Edge Damage Criteria ** ON A/C NOT FOR ALL

(4) The following observations are acceptable:
(a) Rough edges due to erosion or nicks without significantly displaced material are acceptable (4).
(b) Discoloration of the blade is acceptable.
(c) Indications of impeller to shroud incursions (rubs) are acceptable.
(d) Accumulation of shroud abradable material on blade is acceptable (5).
(5) The following observations are not acceptable, the observations are criteria for APU removal:
(a) Remove the APU if visible cracks of the trailing edge, shroud line and/or hub are observed (7) or visible pieces are missing (6).
(6) Remove optic fiber borescope from the load compressor borescope port.
(7) Lubricate new AIPC 49-23-09-01-160 PACKING (2) or AIPC 49-23-84-30-140 PACKING (2) with Mineral base Lubricating Oil-Turbine Engine - - (Material No.03BEB1) and install it on the plug (1).
(8) Install plug (1) on load compressor borescope port.
(9) TORQUE the plug (1) to between 0.99 and 0.81 m.daN (87.61 and 71.68 lbf.in )

.
(10) Safety the plug (1).

(a) Safety the plug (1) with 14QEB1Wire-Locking Dia: 0.6 mm CRES Nickel Alloy -.

Subtask 49-20-00-960-054-B ** ON A/C NOT FOR ALL

CAUTION: MAKE SURE THE APU INTERNAL TEMPERATURE IS NOT MORE THAN 80 DEG.C (176 DEG.F) BEFORE YOU PUT THE BORESCOPE INTO THE APU. HEAT CAN CAUSE DAMAGE TO THE BORESCOPE.

CAUTION: BEFORE YOU ROTATE THE APU, MAKE SURE THAT THE BORESCOPE IS NOT IN THE RANGE OF THE COMPRESSOR IMPELLER BLADES. THE ROTATION OF THE BLADES CAN CAUSE DAMAGE TO THE BORESCOPE.

Load-Compressor Trailing-Edge Damage Criteria ** ON A/C NOT FOR ALL

(4) The following observations are acceptable:
(a) Rough edges due to erosion or nicks without significantly displaced material are acceptable (4).
(b) Discoloration of the blade is acceptable.
(c) Indications of impeller to shroud incursions (rubs) are acceptable.
(5) The following observations are not acceptable, the observations are criteria for APU removal:
(a) Remove the APU if visible cracks of the trailing edge, shroud line and/or hub are observed (7) or visible pieces are missing (6).
(6) Remove optic fiber borescope from the load compressor borescope port.
(7) Lubricate new AIPC 49-23-09-01-160 PACKING (2) or AIPC 49-23-84-30-140 PACKING (2) with Mineral base Lubricating Oil-Turbine Engine - - (Material No.03BEB1) and install it on the plug (1).
(8) Install plug (1) on load compressor borescope port.
(9) TORQUE the plug (1) to between 0.99 and 0.81 m.daN (87.61 and 71.68 lbf.in )

.
(10) Safety the plug (1).

(a) Safety the plug (1) with 14QEB1Wire-Locking Dia: 0.6 mm CRES Nickel Alloy -.

Subtask 49-20-00-960-055-A ** ON A/C NOT FOR ALL

C. Examine the Inlet Guide Vanes for Damage

Clevis Assembly and Attaching Bolt ** ON A/C NOT FOR ALL

(1) Loosen bolts that hold the cover plate and rotate the cover plate clockwise to access the clevis assembly.
(2) Remove the bolt that holds the inlet guide vane actuator (IGVA) and clevis assemblies together (Ref. AMM TASK 49-23-51-000-004).
(3) Pull the inlet guide vane linkage, by hand, into the engine assembly until the linkage stops and the inlet guide vanes are fully closed.
(4) Put the optic fiber borescope through the compressor inlet duct and perforated inlet housing to the inlet guide vanes.
(5) Examine the guide vanes for evidence of damage.

Inlet Guide Vane (IGV) Damge Criteria (IGV closed) ** ON A/C NOT FOR ALL

(6) The following observations are acceptable:
(a) Leading edge nicks (9).
(b) Blade discoloration (8).
(7) The following observations are not acceptable, the observations are criteria for APU removal:
(a) Cracked, bent or missing vanes not permitted (10),(13),(12).
(b) Impact damage to all the vane tips against adjacent shaft is indication of rotor imbalance, APU should be removed in this case (11).
(8) Push the inlet guide vane linkage, by hand, into the engine assembly until the linkage stops and the inlet guide vanes are fully open.
(9) Put the optic fiber borescope through the compressor inlet duct and perforated inlet housing to the inlet guide vanes.
(10) Examine the inlet guide vanes for evidence of damage.

Inlet Guide Vane (IGV) Damage Criteria (IGV open) ** ON A/C NOT FOR ALL

(11) The following observations are acceptable:
(a) Leading edge nicks (15).
(b) Blade discoloration (14).
(12) The following observations are not acceptable, the observations are criteria for APU removal:
(a) Cracked, bent or missing vanes not permitted (16), (17) and (18).
(b) Impact damage to all vane tips against adjacent shaft is indication of rotor imbalance, APU should be removed in this case (19).

Subtask 49-20-00-960-056-A ** ON A/C NOT FOR ALL

D. Examine the Load-Compressor Impeller Leading-Edge for Damage

CAUTION: MAKE SURE THE APU INTERNAL TEMPERATURE IS NOT MORE THAN 80 DEG.C (176 DEG.F) BEFORE YOU PUT THE BORESCOPE INTO THE APU. HEAT CAN CAUSE DAMAGE TO THE BORESCOPE.

CAUTION: BEFORE YOU ROTATE THE APU, MAKE SURE THAT THE BORESCOPE IS NOT IN THE RANGE OF THE COMPRESSOR IMPELLER BLADES. THE ROTATION OF THE BLADES CAN CAUSE DAMAGE TO THE BORESCOPE.

(1) Push the borescope behind the inlet guide vanes to examine the load compressor leading-edges.
(2) Prepare to turn the rotating group to examine the load compressor impeller:
(a) Remove the cap from the end of the starter.
(b) Put the SOCKET DIA 5/16 IN - HEXAGONAL, with the EXTENSION LENGHT 6 IN (152,4 MM) and the ratchet wrench, onto the 5/16 inch hexagonal shaft at the end of the starter.
(3) Turn the rotating group as necessary and examine the load-compressor impeller leading-edges

Load-Compressor Impeller Leading-Edge-Damage Conditions ** ON A/C NOT FOR ALL

(4) The damage and changes that follow are permitted:
(a) Bent inducer blade tips (20)
(b) Leading edge nicks and rough edges because of erosion are without too much displaced material (21)
(c) Discoloration of the blade (22).
(5) If you find the damage and changes that follow, remove the APU:
(a) Cracks (24) that you can see on the leading edge, fillets, hub or missing parts (23).
(6) Remove the optic fiber borescope from the compressor inlet duct.
(7) Install the bolt that holds the Inlet Guide Vane (IGV) actuator and clevis assemblies together (Ref. AMM TASK 49-23-51-400-004).
(8) Turn the cover plate counterclockwise to close the clevis assembly access-opening and TORQUE the bolts to between 0.627 and 0.513 m.daN (55.49 and 45.40 lbf.in )

.
(9) Install a cap on the end of starter.

Subtask 49-20-00-960-057-A ** ON A/C NOT FOR ALL

E. Examine the Engine Compressor Impeller for Damage
(1) Prepare to turn the rotating group to examine engine compressor impeller blades.
(a) Remove cap from the end of the starter.
(b) Insert a SOCKET DIA 5/16 IN - HEXAGONAL, with attached 6 inch extension and ratchet wrench, onto the 5/16 inch hex shaft on the end of the starter.
(2) Put the optic fiber borescope through the compressor inlet duct and perforated inlet housing to examine the engine compressor impeller.

CAUTION: MAKE SURE THE APU INTERNAL TEMPERATURE IS NOT MORE THAN 80 DEG.C (176 DEG.F) BEFORE YOU PUT THE BORESCOPE INTO THE APU. HEAT CAN CAUSE DAMAGE TO THE BORESCOPE.

CAUTION: BEFORE YOU ROTATE THE APU, MAKE SURE THAT THE BORESCOPE IS NOT IN THE RANGE OF THE COMPRESSOR IMPELLER BLADES. THE ROTATION OF THE BLADES CAN CAUSE DAMAGE TO THE BORESCOPE.

(3) Turn the rotating group as necessary and examine the engine compressor impeller leading edges.

Engine Compressor-Impeller Damage Criteria ** ON A/C NOT FOR ALL

NOTE: The trailing edge of the engine compressor impeller is not accessible for borescope examination while APU is installed on the aircraft.

(4) The following observations are acceptable:
(a) Bent inducer main or splitter blade tips are permitted on one blade only (26).
(b) Rough edges due to nicks or erosion without significantly displaced material are acceptable (27).
(c) Discoloration of impeller blades is acceptable (29).
(d) Indications of impeller to shroud incursions (rubs) are acceptable (28).
(5) The following observations are not acceptable, the observations are criteria for APU removal:
(a) Remove the APU if there are visible cracks of the leading edge, fillets, hub (30) or visible pieces are missing (31).

Subtask 49-20-00-960-058-A ** ON A/C NOT FOR ALL

F. Examine the Engine Compressor Diffuser for Damage
(1) Push borescope past the leading edge of the engine compressor impeller and examine the Engine Compressor Diffuser vanes for damage.

Compressor-Diffuser Damage Criteria ** ON A/C NOT FOR ALL

(2) The following observations are acceptable:
(a) Leading edge nicks and rough edges due to erosion are acceptable without significantly displaced material (32).
(b) Discoloration of vanes is acceptable.
(c) Cracks found in the braze fillet area are acceptable (33).
(3) The following observations are not acceptable, the observations are criteria for APU removal:
(a) Bucket shaped erosion is not acceptable (34).
(4) Remove optic fiber borescope from the compressor inlet.
(5) Install cap on end of starter.

Subtask 49-20-00-960-059-A ** ON A/C NOT FOR ALL

G. Examine the Combustor for Damage

Combustor Damage Criteria ** ON A/C NOT FOR ALL

(1) Remove the igniter plug from the engine assembly (Ref. AMM TASK 49-41-41-000-005).
(a) Put the optic fiber borescope through the igniter plug port.
(b) The damage and changes that follow are permitted:
1 Discoloration of the panels and blocked effusion holes (35)
2 Missing or damaged thermal barrier coat on the outer transition liner (37)
3 Cracks between holes, if there is no material breakaway or if the pattern of the cracks cannot cause a loss of material (36).
(c) If you find the damage and changes that follow, remove the APU::
1 Hot spots with dangerous oxidation and/or erosion that cause a loss of material (37)
2 Cracks on the inner transition liner with the conditions that follow:

NOTE: It can be necessary to put the borescope at other locations to do this check.

a Make sure that there are no signs of open cracks or cracks that are more than 180 degrees continuously (55):

Carbon deposits more than 0.25 IN. (6.35 MM) thick
Intersecting cracks.

3 Examine the fuel nozzle shrouds for cracks, distortion, or burn-through. No cracks, distortion or burn-through are permitted:

Combustion Chamber ** ON A/C NOT FOR ALL

a If you find a damaged fuel nozzle shroud, replace it with a serviceable fuel nozzle shroud.
(d) Remove the optic fiber borescope from the igniter plug port.

Subtask 49-20-00-960-060-A ** ON A/C NOT FOR ALL

CAUTION: MAKE SURE THE APU INTERNAL TEMPERATURE IS NOT MORE THAN 80 DEG.C (176 DEG.F) BEFORE YOU PUT THE BORESCOPE INTO THE APU. HEAT CAN CAUSE DAMAGE TO THE BORESCOPE.

H. Examine the first stage turbine nozzle assembly for damage

NOTE: Stator vanes removed with minor base-material exposure can be economically reworked and returned to service.

(1) Put the optic fiber borescope through the igniter plug port.

NOTE: Use of borescope guide tube will be helpful to guide borescope to leading edge of first stage turbine nozzle.
Ask your local Honeywell Field Service Engineer (FSE).

(2) Adjust the borescope as necessary to examine the first stage turbine nozzles for damage.
(3) Examine the first stage turbine nozzle assembly for the conditions that follow.

First Stage Turbine-Nozzle Assy Damage Criteria ** ON A/C NOT FOR ALL

(a) The following observations are acceptable:
1 Leading edge or trailing edge cracks and vane material corrosion are acceptable (41) and (39).
2 Discoloration is acceptable.
3 Nicks are acceptable (41).
4 Missing material at trailing edge which does not extend forward beyond a line connecting the cooling discharge passages is acceptable (38).
(b) The following observations are not acceptable, the observations are criteria for APU removal:
1 Examine all passages between vanes for possible entrapped material from different source. No entrapped material permitted.
2 Broken vanes with missing pieces of vane leading edges are not permitted (42).
3 Through wall holes in vane leading edges exposing internal passages are not permitted (42).
4 Missing material at trailing edge which extends forward beyond a line connecting the cooling discharge passages is not acceptable (40).
(4) If the condition of the turbine nozzle is suspect, a review of the CT5ATP value is possible (Ref. AMM TASK 49-00-00-970-001).
(a) If CT5ATP is higher than 653 deg.C (1207.40 deg.F), do the related troubleshooting procedure TSM 49-00-81-810-835.

Subtask 49-20-00-960-061-A ** ON A/C NOT FOR ALL

I. Examine the first stage turbine blades for damage
(1) Prepare to turn the rotating group to examine first stage turbine blades.
(a) Remove cap from the end of the starter.
(b) Insert a SOCKET DIA 5/16 IN - HEXAGONAL, with attached 6 inch extension and ratchet wrench, onto the 5/16 inch hex shaft on the end of the starter.

CAUTION: MAKE SURE THE APU INTERNAL TEMPERATURE IS NOT MORE THAN 80 DEG.C (176 DEG.F) BEFORE YOU PUT THE BORESCOPE INTO THE APU. HEAT CAN CAUSE DAMAGE TO THE BORESCOPE.

(2) Adjust the borescope as necessary to examine the first stage turbine rotor blades for damage.

CAUTION: BEFORE YOU ROTATE THE APU, MAKE SURE THAT THE BORESCOPE IS NOT IN THE RANGE OF THE COMPRESSOR IMPELLER BLADES. THE ROTATION OF THE BLADES CAN CAUSE DAMAGE TO THE BORESCOPE.

(3) Turn the rotating group as necessary and examine the first stage turbine blades for the conditions that follow

First Stage Turbine-Blade Damage Criteria ** ON A/C NOT FOR ALL

(a) The following observations are acceptable:
1 Blade tip corrosion is permitted (45).
2 Missing flow discouragers on leading or trailing edge of turbine wheel is acceptable (46).
3 Discoloration of blades are acceptable (43).
4 Nicks on leading edge, trailing edge and blade tip is acceptable (44).
(b) The following observations are not acceptable, the observations are criteria for APU removal:
1 Remove the APU if there are cracked or missing blades (47).
2 Remove the APU if there is blade walking condition (53).
(4) If the condition of the turbine blade is suspected, a review of the CT5ATP value is possible (Ref. AMM TASK 49-00-00-970-001).
(a) If CT5ATP is higher than 653 deg.C (1207.40 deg.F), do the related troubleshooting procedure TSM 49-00-81-810-835.
(5) Remove the borescope from the igniter plug port.
(6) Install igniter plug in the engine assembly (Ref. AMM TASK 49-41-41-400-004).

Subtask 49-20-00-960-062-A ** ON A/C NOT FOR ALL

J. Examine the Second Stage Turbine Blades for Damage
(1) Prepare to turn the rotating group to examine second stage turbine blades:
(a) Remove cap from the end of the starter.
(b) Insert a SOCKET DIA 5/16 IN - HEXAGONAL, with attached 6 inch extension and ratchet wrench, onto the 5/16 inch hex shaft on the end of the starter.

CAUTION: MAKE SURE THE APU INTERNAL TEMPERATURE IS NOT MORE THAN 80 DEG.C (176 DEG.F) BEFORE YOU PUT THE BORESCOPE INTO THE APU. HEAT CAN CAUSE DAMAGE TO THE BORESCOPE.

(2) Remove EGT thermocouple from the engine assembly (Ref. AMM TASK 49-72-15-000-002).
(3) Put the borescope into the EGT thermocouple port.
(4) Adjust the borescope as necessary to examine the second stage turbine rotorblades for damage.
(5) Turn the rotating group as necessary and examine the second stage turbine blades for the conditions that follow.

Second Stage Turbine-Blade Damage Criteria ** ON A/C NOT FOR ALL

(a) The following observations are acceptable:
1 Blade tip corrosion is permitted (48).
2 Missing flow discouragers on leading or trailing edge of turbine wheel is acceptable (51).
3 Discoloration of blades is acceptable (50).
4 Nicks on leading edge, trailing edge and blade tip is acceptable (49).
(b) The following observations are not acceptable, the observations are criteria for APU removal:
1 Remove the APU if there are cracked or missing blades (52).
(6) If the condition of the turbine blade is suspect, a review of the CT5ATP value is possible (Ref. AMM TASK 49-00-00-970-001).
(a) If CT5ATP is higher than 653 deg.C (1207.40 deg.F), do the related troubleshooting procedure TSM 49-00-81-810-835.

NOTE: Second stage stator vanes are not accessible with borescope. Assessment of acceptance should be made based on condition of first stage turbine nozzle and first stage turbine wheel.

(7) Remove the borescope from the EGT thermocouple port.
(8) Install EGT thermocouple in the engine assembly (Ref. AMM TASK 49-72-15-400-003).
(9) Install cap in the end of the starter.

5. Close-up
Subtask 49-20-00-410-070-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Set the LIGHT SW 11LJ to the OFF position.
(3) Close the APU access doors 316AR 315AL (Ref. AMM TASK 52-41-00-410-001).
(4) Remove the access platform(s).

Subtask 49-20-00-865-089-A ** ON A/C NOT FOR ALL

B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	APU/APU/CTL	2KD	L42
121VU	APU/ECB/SPLY	1KD	L41

Subtask 49-20-00-710-066-A ** ON A/C NOT FOR ALL

C. Test

NOTE: Because components are disconnected or removed during borescope procedure, it is recommended to operate the APU in ECS mode to make sure correct APU operation.

(1) Start the APU (Ref. AMM TASK 49-00-00-860-008).
(2) Operate the APU for at least 5 minutes in ECS mode.
(3) Stop the APU (Ref. AMM TASK 49-00-00-860-009).
(4) Do an inspection of the APU for fuel, oil and air leaks (Ref. AMM TASK 49-00-00-790-003).

NOTE: Leaks are not permitted.

Subtask 49-20-00-860-080-A ** ON A/C NOT FOR ALL

D. Aircraft Maintenance Configuration.
(1) Pressurize the reservoirs of the hydraulic systems.
(Ref. AMM TASK 29-14-00-614-002).
(2) De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).
(3) Remove the ground support and maintenance equipment, the special and standard tools and all other items.
(4) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 04:08:46 UTC