General Visual Inspection (GVI) of the Main Gearbox (MGB) Assembly [PW11]

TASK 72-61-00-210-801-A
General Visual Inspection (GVI) of the Main Gearbox (MGB) 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: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

ZONE: 400

1. Reason for the Job
This task gives instructions for a visual inspections of the Main Gearbox (MGB) for nicks, dents, scratches, cracks, corrosion, mount hardware leakage and missing component mount bolts.
The MGB is mounted on the diffuser case at the 6 o'clock position.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	COVER - PROTECTION

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 70-28-00-910-803-A	SPOP 42 - Chromate Conversion Coating of Aluminum
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 72-61-01-000-801-A	Removal of the Main Gear Box (MGB)
TASK 72-61-01-100-801-A	Cleaning of the Main Gearbox with a Chemical Agent
TASK 72-61-01-400-801-A	Installation of the Main Gear Box (MGB)
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
General Visual Inspection (GVI) of the Main Gearbox (MGB)
General Visual Inspection (GVI) of the Main Gearbox (MGB)
General Visual Inspection (GVI) of the Main Gearbox (MGB)
General Visual Inspection (GVI) of the Main Gearbox (MGB)

3. Job Set-up
Subtask 72-61-00-941-050-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 72-61-00-010-050-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

Subtask 72-61-00-040-050-A ** ON A/C NOT FOR ALL

C. Deactivation of the Thrust Reverser for 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 maintenance (Ref. AMM TASK 78-30-00-040-805).

Subtask 72-61-00-010-051-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
Subtask 72-61-00-210-050-A ** ON A/C NOT FOR ALL

A. General Visual Inspection (GVI) of the Main Gearbox (MGB) Assembly

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

(1) Removal of the protection covers

CAUTION: REMOVE THE PROTECTION COVERS FROM THE OPENINGS AS NECESSARY TO PREVENT ENGINE DAMAGE.

(a) Make sure that you remove all the necessary COVER - PROTECTION to prevent damage to the engine.
(2) If necessary, clean the MGB (Ref. AMM TASK 72-61-01-100-801).
(3) Examine the MGB for nicks, dents, scratches, cracks, corrosion and missing coat. Refer to Table 601.
(4) Examine the MGB for oil leakage from all plugs, chip detectors, installed components and component interfaces.
(a) No leaks are permitted.
1 Correct all leaks as necessary.
(5) Examine the MGB mounting hardware. Refer to Table 602.
(6) Examine the MGB for loose or missing component attachments and various cover retention bolts and nuts that can be seen. Refer to Table 603.

Table 601: Damage Limits for the MGB

EXAMINE	DAMAGE	DISPOSITION
For cracks	Cracks are found.	Remove and replace the MGB (Ref. AMM TASK 72-61-01-000-801) and (Ref. AMM TASK 72-61-01-400-801).
For missing coat	Missing coat	Permitted. Repair with alodine touch-up SPOP 42 at the next opportunity (Ref. AMM TASK 70-28-00-910-803).
For corrosion	Depth of gearbox corrosion is less than 0.040 in. (1.02 mm).	Permitted to continue in service.
	Depth of corrosion is more than 0.040 in. (1.02 mm).	Remove and replace the MGB (Ref. AMM TASK 72-61-01-000-801) and (Ref. AMM TASK 72-61-01-400-801).
	Total surface area with corrosion is less than 1 in.2 (645.16 mm2). See Note.	Gearbox is permitted to continue in service.
	Total surface area with corrosion is more than 1 in.2 (645.16 mm2). See Note.	Remove and replace the MGB (Ref. AMM TASK 72-61-01-000-801) and (Ref. AMM TASK 72-61-01-400-801).
NOTE: Corrosion areas that are less than 2 in. (50.80 mm) apart are counted as one area, but the total surface in that area must be less than 1 in.2 (645.16 mm2) limit.
Nicks and scratches	Any quantity, depth of nicks and scratches is 0.020 in. (0.508 mm) or less.	Permitted
	Any quantity, depth of nicks and scratches is more than 0.020 in. (0.508 mm).	Not permitted. Remove the engine from service in five cycles or less.
Round bottom dents	Any quantity, depth of round bottom dents is 0.020 in. (0.508 mm) or less.	Permitted
	Any quantity, depth of round bottom dents is more than 0.020 in. (0.508 mm).	Not permitted. Remove the engine from service in five cycles or less.

Table 602: General Visual Inspection (GVI) of the MGB Mounting Hardware

EXAMINE	DAMAGE	DISPOSITION
For security of attaching part	Looseness	Tighten as required.
For cracks	Any amount	Not permitted. Replace the gearbox or defective attaching part.

Table 603: General Visual Inspection (GVI) of the MGB

EXAMINE	DAMAGE	DISPOSITION
For loose, missing or broken gearbox cover retention bolts	Not permitted. Replace the bolt or helical coil.	Contact Pratt and Whitney.
For loose, missing or broken lubrication and scavenge oil pump mounting bolts	Not permitted. Replace the bolt or helical coil.	Contact Pratt and Whitney.
For loose, missing or broken oil control module	Not permitted. Replace the bolt or helical coil.	Contact Pratt and Whitney.
For loose or missing oil filter cover nuts	Not permitted. Replace the nut.	Contact Pratt and Whitney.
For loose, missing or broken pad miscellaneous cover retention bolts.	Not permitted. Replace the bolt, nut or helical coil.	Contact Pratt and Whitney.
For loose, missing or broken permanent magnet alternator/generator mounting bolts	Not permitted. Replace the bolt or helical coil.	Contact Pratt and Whitney.
For loose or broken engine driven pump bolts	Not permitted. Replace the bolt or helical coil.	Contact Pratt and Whitney.

(7) Examine the assembly for unwanted objects, damage and correct assembly.
(8) Installation of the protection covers

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

(a) Make sure that you install all the necessary COVER - PROTECTION to prevent damage to the engine.

5. Close-up
Subtask 72-61-00-860-050-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.
(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 72-61-00-410-050-A ** ON A/C NOT FOR ALL

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

Subtask 72-61-00-440-050-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 WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 02:49:52 UTC