Borescope Inspection of the Low Pressure Compressor (LPC) Assembly [PW11]

TASK 72-31-00-290-802-A
Borescope Inspection of the Low Pressure Compressor (LPC) Assembly

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AFTER SHUTDOWN. THE ENGINE CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS INSTRUCTION, INJURY CAN OCCUR.

WARNING: DO THE BORESCOPE INSPECTION IN AN AREA WHICH HAS PROTECTION FROM THE WEATHER. IF A BORESCOPE INSPECTION IS DONE IN WET CONDITIONS, USE SUFFICIENT PROTECTION TO PREVENT POSSIBLE ELECTRICAL SHOCK TO THE OPERATOR OR DAMAGE TO THE EQUIPMENT. AN ELECTRICAL SHOCK CAN KILL A PERSON OR CAUSE A BAD INJURY.

CAUTION: MAKE SURE THE TEMPERATURE IN THE ENGINE IS LESS THAN 150 DEG.F (65.6 DEG.C) BEFORE YOU INSTALL THE FLEXIBLE BORESCOPE IN THE ENGINE. IF THE ENGINE IS HOTTER THAN 150 DEG.F (65.6 DEG.C), THE FLEXIBLE BORESCOPE CAN MELT AND BE DAMAGED.

CAUTION: BEFORE YOU REMOVE THE LPC BORESCOPE PLUGS, WAIT UNTIL THE LPC INTERNAL CAVITY TEMPERATURE IS LESS THAN 150 DEG F (65 DEG C). LPC BORESCOPE PLUGS CAN BREAK BECAUSE OF CASE MISALIGNMENT. DAMAGE TO THE LPC CAN OCCUR IF YOU TRY TO REMOVE THE BORESCOPE PLUGS WHEN THE ENGINE IS HOT.

ZONE: 400

1. Reason for the Job
Use this inspection procedure to examine the Low Pressure Compressor (LPC) assembly.
For more information about the engine, refer to (72-00-00-00U).
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 1M(3 FT)
No specific	1	THERMOMETER - METAL PROBE TYPE, 0 TO 400 DEG.F
CTE8003	1	SYSTEM BOROSCOPE (VIDEO)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
400	POWER PLANT, NACELLES AND PYLONS
FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
437AL, 438AR, 451AL, 452AR
FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
447AL, 448AR, 461AL, 462AR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 71-00-00-860-833-A	Procedure to Prevent Engine Motoring
TASK 71-13-00-010-802-A	Opening of the Fan Cowl Doors
TASK 71-13-00-410-802-A	Closing of the Fan Cowl Doors
TASK 72-00-00-000-804-A	Removal of the Borescope Plugs
TASK 72-00-00-400-804-A	Installation of the Borescope Plugs
TASK 72-31-01-300-802-A	Low Pressure Compressor (LPC) Integrally Bladed Rotor Borescope Blend Repair
TASK 78-30-00-040-805-A	Deactivation of the Thrust Reverser System for Ground Maintenance
TASK 78-30-00-440-805-A	Reactivation of the Thrust Reverser System after Ground Maintenance
TASK 78-36-00-010-802-A	Opening of the Thrust Reverser Cowl-Doors
TASK 78-36-00-410-802-A	Closing of the Thrust Reverser Cowl-Doors
Borescope Inspection of the Low Pressure Compressor - (Vane and Blade Locations)
Borescope Inspection of the Low Pressure Compressor - (Variable Inlet Guide Vanes)
Borescope Inspection of the Low Pressure Compressor - (1st and 2nd Stage Vanes)
Borescope Inspection of the Low Pressure Compressor - (1st, 2nd, and 3rd Stage Rotor Blades and Rubstrips)
Borescope Inspection of the Low Pressure Compressor - (Cross- Sectional Views (Typical) of LPC Rotor Blades and Vanes)
Borescope Inspection of the Low Pressure Compressor - (Distances Between Leading and Trailing Edges for LPC Vanes and Blades)
Borescope Inspection of the Low Pressure Compressor - (LPC Access Port (AP) Locations)

3. Job Set-up
Subtask 72-31-00-941-062-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) Do the procedure to prevent engine motoring
(Ref. AMM TASK 71-00-00-860-833).

Subtask 72-31-00-010-068-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-802):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
447AL 448AR.
(2) Put an ACCESS PLATFORM 1M(3 FT) in position.

Subtask 72-31-00-040-056-A ** ON A/C NOT FOR ALL

C. Deactivation of the Thrust Reverser for Ground Maintenance

WARNING: YOU MUST DEACTIVATE THE THRUST REVERSER BEFORE YOU DO WORK ON OR AROUND IT. IF YOU DO NOT, THE THRUST REVERSER CAN OPERATE ACCIDENTALLY AND CAUSE AN INJURY AND/OR DAMAGE.

(1) Do the deactivation of the thrust reverser system for ground maintenance (Ref. AMM TASK 78-30-00-040-805).

Subtask 72-31-00-010-069-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Open the thrust reverser cowl-doors (Ref. AMM TASK 78-36-00-010-802):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
451AL 452AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
461AL 462AR.

4. Procedure

CAUTION: WIPE CLEAN ALL PARTS AND TOOLS AS NECESSARY TO REMOVE UNWANTED DEBRIS AND PREVENT DAMAGE TO THE ENGINE.

Subtask 72-31-00-290-055-A ** ON A/C NOT FOR ALL

A. Borescope Inspection of the Low Pressure Compressor (LPC) Assembly
(1) If the engine was run recently, measure the temperature in the LPC with a THERMOMETER - METAL PROBE TYPE, 0 TO 400 DEG.F.
(a) It is recommended that you wait three to five hours after engine shutdown before you do a borescope inspection.
(2) Remove the AP LPC-1 PLUG (3), AP LPC-2 PLUG (4) and AP LPC-3 PLUG (1) (Ref. AMM TASK 72-00-00-000-804).

Borescope Inspection of the Low Pressure Compressor - (LPC Access Port (AP) Locations) ** ON A/C NOT FOR ALL

(3) Do the inspection of the LPC assembly:

WARNING: BE CAREFUL TO EXAMINE THE POWER CABLE OF THE LIGHT SOURCE BEFORE YOU USE IT. DO NOT USE THE CABLE IF THE INSULATION HAS CUTS OR WORN OR BROKEN AREAS. INSULATION WITH THIS TYPE OF DAMAGE IS DANGEROUS BECAUSE OF POSSIBLE ELECTRICAL SHOCK TO THE OPERATOR.

CAUTION: INSTALL PROTECTION COVERS ON ALL OPENINGS IMMEDIATELY TO PREVENT DAMAGE TO THE ENGINE.

(a) Do the inspection with the CTE8003 SYSTEM BOROSCOPE (VIDEO).
(4) Turn the fan clockwise to turn the LPC counterclockwise:

CAUTION: DO NOT USE THE LPT 3RD STAGE BLADES TO TURN THE LPC ROTOR. ONLY USE THE FAN BLADES. IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE LPT BLADES AND/OR THE ENGINE CAN OCCUR.

(a) Turn the fan clockwise to turn the LPC counterclockwise (as seen from the rear) during inspection.

NOTE: Turn the fan clockwise as seen from the rear (normal operation). If the fan is accidentally turned counterclockwise, there can be some resistance. This condition is permitted, but do not continue to turn the fan in the counterclockwise (incorrect) direction.

NOTE: You can use a flexible borescope as an alternative in the steps that follow.

(5) Turn the fan blades to turn the LPC to examine each LPC rotor blade.

NOTE: Examine the LPC vanes and blades during the borescope inspection for blend repairs. It is possible to see an area that is worn more than the permitted damage limits because of a blend repair that was done before. You must examine this area very carefully to find if this area is a new defect or an area that was blend repaired before. A blend repaired area will have a minimum 4 to 1 length to depth blend ratio with smooth round corners.

(6) Do the LPC borescope inspection for the LPC access port (AP), vane and blade locations.

Borescope Inspection of the Low Pressure Compressor - (LPC Access Port (AP) Locations) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Vane and Blade Locations) ** ON A/C NOT FOR ALL

NOTE: It is necessary to count the blades of the LPC because of the gear ratio (approximately 3:1). One full rotation of the fan does not equal one full rotation of the low rotor.
The 1st stage LPC rotor has 32 blades.
The 2nd stage LPC rotor has 52 blades.
The 3rd stage LPC rotor has 68 blades.

NOTE: This examination shows only what you can see with the flexible borescope through the borescope access ports AP LPC-1 thru AP LPC-3.

NOTE: This inspection of all vane stages is not mandatory for 360 degrees for AP LPC-1 thru AP LPC-3. Limits are applicable if damage is seen when the borescope is put into one of the LPC APs. This is only applicable to vanes that are immediately in view and to which you have access.

(7) Examine the LPC through AP LPC-1.

NOTE: You can turn the vanes to increase access, if necessary.

(a) Examine the LPC variable inlet guide vanes. See Table 601.

Borescope Inspection of the Low Pressure Compressor - (Variable Inlet Guide Vanes) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Cross- Sectional Views (Typical) of LPC Rotor Blades and Vanes) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Distances Between Leading and Trailing Edges for LPC Vanes and Blades) ** ON A/C NOT FOR ALL

(b) Examine the 1st stage rotor blades and rubstrip. See Table 602.

Borescope Inspection of the Low Pressure Compressor - (1st, 2nd, and 3rd Stage Rotor Blades and Rubstrips) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Distances Between Leading and Trailing Edges for LPC Vanes and Blades) ** ON A/C NOT FOR ALL

(8) Examine the LPC through AP LPC-3.

NOTE: If new damage is found at any of the above noted stages, you must examine all of the LPC stages behind the stage that shows the new damage and all stages forward to the AP location that showed a normal borescope indication before. It will be necessary to remove applicable AP plugs to examine other LPC stages.

(a) Examine the LPC 2nd stage vanes. See Table 601.

Borescope Inspection of the Low Pressure Compressor - (1st and 2nd Stage Vanes) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Cross- Sectional Views (Typical) of LPC Rotor Blades and Vanes) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Distances Between Leading and Trailing Edges for LPC Vanes and Blades) ** ON A/C NOT FOR ALL

(b) Examine the 3rd stage blades and rubstrip. See Table 603.

Borescope Inspection of the Low Pressure Compressor - (1st, 2nd, and 3rd Stage Rotor Blades and Rubstrips) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Cross- Sectional Views (Typical) of LPC Rotor Blades and Vanes) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Distances Between Leading and Trailing Edges for LPC Vanes and Blades) ** ON A/C NOT FOR ALL

(9) Borescope other LPC stages as necessary to identify damage.

NOTE: This step is required following a surge or stall event or if new damage is found as described above.

(a) Put the borescope through AP LPC-2 port to examine the LPC 1st stator vanes, LPC 2nd stage blades and rubstrip.
1 Examine the LPC 1st stage vanes. See Table 601.

Borescope Inspection of the Low Pressure Compressor - (1st and 2nd Stage Vanes) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Cross- Sectional Views (Typical) of LPC Rotor Blades and Vanes) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Distances Between Leading and Trailing Edges for LPC Vanes and Blades) ** ON A/C NOT FOR ALL

2 Examine the 2nd stage rotor blades and rubstrip. See Table 603.

Borescope Inspection of the Low Pressure Compressor - (1st, 2nd, and 3rd Stage Rotor Blades and Rubstrips) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Cross- Sectional Views (Typical) of LPC Rotor Blades and Vanes) ** ON A/C NOT FOR ALL

Borescope Inspection of the Low Pressure Compressor - (Distances Between Leading and Trailing Edges for LPC Vanes and Blades) ** ON A/C NOT FOR ALL

Table 601 - Borescope Inspection/Limits for LPC Variable Inlet Guide Vanes (VIGV) through LPC 2nd Stage Vanes

EXAMINE	DAMAGE	DISPOSITION
Area A: Leading and trailing edges, concave and convex radial surfaces for cracks, tears, nicks, dents, pitting, corrosion or other surface damage	Any quantity	Not permitted. Remove the engine from service.
Area B: platform area for cracks	Any quantity	Not permitted. Remove the engine from service.
Area B: platform areas for nicks and dents	Any quantity 0.015 in. (0.38 mm) or less	Permitted
	Any quantity more than 0.015 in. (0.38 mm) and less than 0.030 in. (0.76 mm) depth	Not permitted. Remove engine within five flight cycles.
	Any quantity more than 0.030 in. (0.76 mm) depth	Not permitted. Remove the engine from service.
Area B: platform areas for pitting and corrosion	Any quantity 0.005 in. (0.13 mm) or less	Permitted
	Any quantity more than 0.005 in. (0.13 mm)	Not permitted. Remove engine before the next flight.
Area C: vane convex and concave surfaces for cracks	Any quantity	Not permitted. Remove the engine from service.
Area C: vane convex and concave surfaces for nicks and dents	Any quantity less than 0.010 in. (0.25 mm) depth that are separated from other nicks and dents by 1.0 in. (25.40 mm).	Permitted
	Nicks and dents more than 0.010 in. (0.25 mm) depth	Not permitted. Remove the engine from service.
Area C: vane convex and concave surfaces for pitting and corrosion	Any quantity 0.005 in. (0.13 mm) or less	Permitted
	Any quantity more than 0.005 in. (0.13 mm)	Not permitted. Remove engine before the next flight.
Area C: vane leading and trailing edge for tears and cracks	Any quantity	Not permitted. Remove the engine from service.
Area C: vane leading and trailing edge for nicks and dents	Any quantity 0.025 in. (0.63 mm) or less	Permitted
	Any quantity more than 0.025 in. (0.635 mm) maximum depth	Not permitted. Remove the engine from service.
	Nicks or dents at two or more locations on the leading edge with 0.500 in. (12.70 mm) or more separation	Permitted
	Nicks or dents at two or more locations on the leading edge with 0.500 in. (12.70 mm) or less separation	Not permitted. Remove the engine from service.
	Nicks or dents at both leading edge and trailing edge that are radially apart by 0.500 in. (12.700 mm) minimum.	Permitted
	Nicks or dents at two or more locations on the trailing edge with 0.500 in. (12.70 mm) or less separation	Not permitted. Remove the engine from service.
	Nicks or dents at both trailing edge and leading edge that are radially apart by a minimum of mean chordal length.	Permitted
	Nicks or dents at both trailing edge and leading edge that are directly opposite each other or radially apart by less than mean chordal length.	Not permitted. Remove the engine from service.
Area C: blade airfoil leading and trailing edge for pitting and corrosion	Any quantity 0.005 in. (0.13 mm) or less	Permitted
	Any quantity more than 0.005 in. (0.13 mm)	Not permitted. Remove engine before the next flight.
Area C: All areas for distance between surface damages	1.000 in. (25.40 mm) separation minimum	Permitted
	Less than 1.000 in. (25.40 mm) separation	Not permitted. Remove engine within five flight cycles.

Table 602 - Borescope Inspection/Limits for LPC 1st Stage Rotor Blades

EXAMINE	DAMAGE	DISPOSITION
Area A: blade airfoil leading and trailing edges, and blade convex and concave surfaces for tears, cracks, pitting, or corrosion	Any quantity	Not permitted. Remove the engine from service or contact Pratt & Whitney.
Area A: blade airfoil leading and trailing edge for nicks and dents	Any quantity	Not permitted. Remove the engine from service or contact Pratt & Whitney.
Area B: leading and trailing edges, blade convex and concave surfaces for cracks, pitting, or corrosion	Any quantity	Not permitted. Remove the engine from service or contact Pratt & Whitney.
Area B: leading and trailing edges for nicks and dents	One round bottom dent, each on the leading and trailing edges, to 0.004 in. (0.102 mm) maximum depth and 0.220 in. (5.588 mm) maximum spanwise length, if the spanwise length is a minimum of three times the maximum depth, with no raised material or sharp edges. Minimum spanwise separation must be 0.250 in. (6.3500 mm), if the serviceable round bottom dent or blend done before is on the leading and trailing edges of the same blade.	Permitted
	One nick or dent, each on the leading and trailing edges, to 0.025 in. (0.635 mm) maximum depth and 0.250 in. (6.350 mm) maximum spanwise length. Minimum spanwise separation must be 0.250 in. (6.3500 mm), after blend, if the serviceable round bottom dent, blend done before or current blend is on the leading and trailing edges of the same blade.	Remove the engine from service or blend the blades (Ref. AMM TASK 72-31-01-300-802) and repair.
	Damage more than above specified limits	Not permitted. Remove the engine from service or contact Pratt & Whitney.
Area B: blade convex and concave surfaces for nicks and dents	Any quantity	Not permitted. Remove the engine from service or contact Pratt & Whitney.
Area C: blade airfoil leading and trailing edges, concave and convex radial surfaces, and root radius for cracks, tears, nicks, dents, corrosion, pitting, or other surface damage	Any quantity	Not permitted. Remove the engine from service or contact Pratt & Whitney.
Area D: platform area for cracks	Any quantity	Not permitted. Remove the engine from service or contact Pratt & Whitney.
Area D: platform area for nicks and dents	Any quantity	Not permitted. Remove the engine from service or contact Pratt & Whitney.
Area E: blade rubstrips for missing abradable material	Any quantity, no base metal surface view	Permitted
	Any quantity, base metal surface view	Not permitted. Remove the engine from service or contact Pratt & Whitney.

Table 603 - Borescope Inspection/Limits for LPC 2nd and 3rd Stage Rotor Blades

EXAMINE	DAMAGE	DISPOSITION
Area A: blade airfoil tip for broken corners (completely missing) and all other types of damage	Any quantity 0.080 in.2 (51.61 mm2) or less	Permitted
	Any quantity more than 0.080 in.2 (51.61 mm2) and less than 0.125 in.2 (80.65 mm2)	Not permitted. Remove engine within five flight cycles.
	Any quantity more than 0.125 in.2 (80.65 mm2)	Not permitted. Remove the engine from service.
Area A: blade airfoil leading and trailing edges and blade convex and concave surfaces for tears, cracks, pitting or corrosion	Any quantity	Not permitted. Remove the engine from service.
Area A: blade airfoil leading and trailing edge for nicks and dents	Any quantity 0.015 in. (0.38 mm) or less	Permitted
	Any quantity more than 0.015 in. (0.38 mm) and less than 0.030 in. (0.76 mm) depth	Not permitted. Remove engine within five flight cycles.
	Any quantity more than 0.030 in. (0.76 mm) depth	Not permitted. Remove the engine from service.
	Nicks or dents up to 0.015 in. (0.38 mm) maximum depth, radial distance 0.250 in. (6.35 mm) minimum	Permitted
	Nicks or dents up to 0.015 in. (0.38 mm) maximum depth, radial distance less than 0.250 in. (6.35 mm)	Not permitted. Remove the engine from service.
Area B: leading and trailing edges, blade convex and concave surfaces for cracks, pitting or corrosion	Any quantity	Not permitted. Remove the engine from service.
Area B: leading and trailing edges, blade convex and concave surfaces for nicks and dents	Any quantity 0.015 in. (0.38 mm) depth or less with a round bottom shape	Permitted
	Any quantity more than 0.015 in. (0.38 mm) depth	Not permitted. Remove the engine from service.
Area C: blade airfoil leading and trailing edges, concave and convex radial surfaces and root radius for cracks, tears, nicks, dents, corrosion pitting or other surface damage	Any quantity	Not permitted. Remove the engine from service.
Area D: platform area for cracks	Any quantity	Not permitted. Remove the engine from service.
Area D: platform area for nicks and dents	Any quantity	Not permitted. Remove the engine from service.
Area E: blade rubstrips for missing abradable material	Any quantity, no base metal surface view	Permitted
	Any quantity, base metal surface view	Not permitted. Remove the engine from service.

(10) Install the AP LPC-1 PLUG (3), AP LPC-2 PLUG (4) and AP LPC-3 PLUG (1) (Ref. AMM TASK 72-00-00-400-804).

Borescope Inspection of the Low Pressure Compressor - (LPC Access Port (AP) Locations) ** ON A/C NOT FOR ALL

5. Close-up
Subtask 72-31-00-410-072-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) Close the thrust reverser cowl-doors (Ref. AMM TASK 78-36-00-410-802):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
451AL 452AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
461AL 462AR.

Subtask 72-31-00-440-057-A ** ON A/C NOT FOR ALL

B. Do the reactivation of the thrust reverser system after ground maintenance (Ref. AMM TASK 78-30-00-440-805).

Subtask 72-31-00-410-073-A ** ON A/C NOT FOR ALL

C. Close Access
(1) Close the fan cowl doors (Ref. AMM TASK 71-13-00-410-802):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
447AL 448AR.
(2) Remove the access platform(s).
(3) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 13:01:57 UTC