Inspection and Cleaning of the Drain Tubes [CFML]

TASK 71-71-42-290-801-A
Inspection and Cleaning of the Drain Tubes

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE PARTS AFTER THE ENGINE SHUTDOWN. USE APPLICABLE THERMAL GLOVES. THE ENGINE PARTS CAN STAY HOT FOR ONE HOUR AFTER SHUTDOWN AND CAN BURN YOU.

ZONE: 210
ZONE: 400

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	BORESCOPE DIA 0.16 TO 0.24 IN (4 TO 6 MM) - FLEXIBLE
No specific	1	BRUSH - NYLON
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
210	CKPT,FWD COMPT BHD TO FLT COMPT BULKHEAD
400	POWER PLANT, NACELLES AND PYLONS

C. Referenced Information

REFERENCE	DESIGNATION
TASK 71-71-49-000-802-A	Removal of the Drain Tubes
TASK 71-71-49-000-804-A	Removal of the Aft Sump Drain Tube
TASK 71-71-49-400-802-A	Installation of the Drain Tubes
TASK 71-71-49-400-804-A	Installation of the Aft Sump Drain Tube
Brown Surface Varnish Examples (Acceptable Conditions)
One-side Coke Build-up Example (Acceptable Condition)
One-side Heavy Coke Build-up Example (Non-acceptable Condition)
Drain Location
B-sump and Auxiliary Drain Location
Turbine Center Frame B-sump Oil Drain Tubes Location
C-sump Oil Drain Tube Location

3. Job Set-up
Subtask 71-71-42-941-060-A

A. Safety Precautions
(1) On the center pedestal, on ENG panel 115VU:
(a) Make sure that the ENG/MODE selector switch is in the NORM position.
(b) Make sure that the ENG/MASTER 1(2) control switch was in the OFF position not less than five minutes before you do this procedure.
(c) Put WARNING NOTICE(S) in position to tell persons not to operate:

The ENG/MODE selector switch and
The ENG/MASTER 1(2) control switch.

(2) On the ENG section of maintenance panel 50VU:
(a) Make sure that the ON legend of the FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put the WARNING NOTICE(S) in position to tell persons not to energize FADEC 1(2).

4. Procedure
Subtask 71-71-42-210-057-A

A. Criteria for Oil Coke Build-up
(1) The oil coke build-up inside the drain tubes is not acceptable and must be cleaned if at least one section of any length of one tube:

Is covered 360° by oil coke build-up (brown surface varnish is accepted)

Is not circular anymore because of one-sided heavy oil coke build-up.

(2)

Brown Surface Varnish Examples (Acceptable Conditions)

One-side Coke Build-up Example (Acceptable Condition)

One-side Heavy Coke Build-up Example (Non-acceptable Condition)

Subtask 71-71-42-290-050-A

B. Inspection and Cleaning of the B-sump and the Auxiliary Drain

Drain Location

B-sump and Auxiliary Drain Location

Turbine Center Frame B-sump Oil Drain Tubes Location

(1) Find the B-sump drain (1) port in the core drain mast (2).
(2) Put the BORESCOPE DIA 0.16 TO 0.24 IN (4 TO 6 MM) - FLEXIBLE into the engine through the B-sump drain (1) mast port.

NOTE: A 4 mm (0.16 in.) borescope tip is the recommended size to do the borescope inspection procedure on the external main drain oil tube (3) and external auxiliary drain tube (4), internal main drain oil tube (5) and internal auxiliary drain tube (6). A 6 mm (0.24 in.) borescope tip is the maximum size that can be used to do the borescope inspection procedure.

(3) Do a borescope inspection up the B-sump drain (1) through the external main drain oil tube (3) and external auxiliary drain tube (4), internal main drain oil tube (5) and internal auxiliary drain tube (6) until reaching the B-sump and the turbine center frame cavities to examine for blockage because of oil coking and do as follows:
(a) If oil coke build-up is acceptable (defined in Para. 4.A.) in the external main drain oil tube (3) and external auxiliary drain tube (4), internal main drain oil tube (5) and internal auxiliary drain tube (6) to the B-sump and the turbine center frame cavities, the inspection is complete and continued operation is permitted. Go to Para. 5.A.

NOTE: Small oil traces on the inner diameter of the external main drain oil tube (3) and external auxiliary drain tube (4), internal main drain oil tube (5) and internal auxiliary drain tube (6) are permitted.

(b) If oil coke build-up is not acceptable (defined in Para. 4.A.) in the external main drain oil tube (3) and/or external auxiliary drain tube (4), internal main drain oil tube (5) and/or internal auxiliary drain tube (6) to the B-sump and the turbine center frame cavities, do as follows:
1 Remove the external main drain oil tube (3) and/or the external auxiliary drain tube (4) (Ref. AMM TASK 71-71-49-000-802), SUBTASK 71-71-49-020-054-A or SUBTASK 71-71-49-020-055-A.
2 Clean oil coke build-up in the inner diameter of the external main drain oil tube (3) and/or the external auxiliary drain tube (4) with a BRUSH - NYLON. Encase the steel wire elements of the BRUSH - NYLON with rubber or plastic coating to prevent scratching.
3 Clean oil coke build-up in the inner diameter of the internal main drain oil tube (5) and/or the internal auxiliary drain tube (6) with a BRUSH - NYLON. If possible, try to remove oil coke build-up out of the external main drain oil tube (3) and/or external auxiliary drain tube (4), internal main drain oil tube (5) and/or internal auxiliary drain tube (6) and do not push it in the engine.
4 Do a borescope inspection or a visual inspection to make sure that the oil coke build-up in the internal main drain oil tube (5) and the internal auxiliary drain tube (6) is acceptable up to the B-sump and the turbine center frame cavities.

NOTE: Small oil traces on the inner diameter of the internal main drain oil tube (5) and the internal auxiliary drain tube (6) are permitted.

5 If there is unwanted material found or if coke build-up is still not acceptable, do Para. 4.B.(3)(b)3_ and Para. 4.B.(3)(b)4_ again.
6 Install the external main drain oil tube (3) and/or the external auxiliary drain tube (4) (Ref. AMM TASK 71-71-49-400-802), SUBTASK 71-71-49-420-054-A or SUBTASK 71-71-49-420-055-A.

Subtask 71-71-42-290-051-A

C. Inspection and Cleaning of the C-sump Drain Port

C-sump Oil Drain Tube Location

(1) Put the BORESCOPE DIA 0.16 TO 0.24 IN (4 TO 6 MM) - FLEXIBLE into the engine through the C-sump drain mast port.

NOTE: A 4 mm (0.16 in.) borescope tip is the recommended size to do the borescope inspection procedure. A 6 mm (0.24 in.) borescope tip is the maximum size that can be used to do the borescope inspection procedure.

(2) Do a borescope inspection of the C-sump drain though the C-sump drain tube (7) to examine until reaching the C-sump cavity for oil coke build-up and do as follows:
(a) If coke build-up is acceptable (defined in Para. 4.A.) in the sections of the C-sump drain tube (7) to the C-sump cavity, the inspection is complete and continued operation is permitted. Go to Para. 5.A.

NOTE: Small oil traces on the inner diameter of the C-sump drain tube (7) are permitted.

(b) If coke build-up is not acceptable (defined in Para. 4.A.) in the sections of the C-sump drain tube (7) to the C-sump cavity, do as follows:
1 Remove the C-sump drain tube (7) (Ref. AMM TASK 71-71-49-000-804).
2 Clean oil coke build-up in the inner diameter of the C-sump drain tube (7) with a BRUSH - NYLON. Encase the steel wire elements of the BRUSH - NYLON with rubber or plastic coating to prevent scratching.
3 Do a borescope inspection or a visual inspection to make sure that oil coke build-up in the internal C-sump drain tube (7) is acceptable up to the C-sump cavity.

NOTE: Small oil traces on the inner diameter of the C-sump drain tube (7) are permitted.

4 If there is unwanted material found or if oil coke build is still not acceptable, do Para. 4.C.(2)(b)2_ and Para. 4.C.(2)(b)3_ again.
5 Install the C-sump drain tube (7) (Ref. AMM TASK 71-71-49-400-804).

5. Close-up
Subtask 71-71-42-410-056-A

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.02 06:33:33 UTC