Removal of the Air-Conditioning Distribution Ducts

TASK 21-20-00-010-001-A
Removal of the Air-Conditioning Distribution Ducts

WARNING: MAKE SURE THAT AIR IS NOT SUPPLIED TO THE AIR CONDITIONING SYSTEM FROM THE MAIN ENGINE, THE APU OR A GROUND SOURCE. HOT COMPRESSED AIR CAN CAUSE INJURY TO PERSONNEL.

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

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 2M (6 FT)
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
811, 824, 825, 826

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 25-13-41-000-001-A	Removal of the Ceiling Panels
TASK 25-23-42-000-001-A	Removal of the Ceiling Panels - Forward Utility Area
TASK 25-23-43-000-001-A	Removal of the Upper Sidewall Panel
TASK 25-23-44-000-001-A	Removal of the Lower Sidewall Panels (Dado Panels)
TASK 25-41-41-000-001-A	Removal of Lavatory A
TASK 25-41-41-000-001-B	Removal of Lavatory A
TASK 25-54-12-000-001-A	Removal of the Forward Cargo-Compartment Partition
TASK 25-54-12-000-002-A	Removal of the Ceiling Panels in the Forward Cargo Compartment
TASK 25-54-12-000-003-A	Removal of the Sidewall Panels in the Forward Cargo Compartment
TASK 25-55-11-000-001-A	Removal of the Aft Cargo-Compartment Partition at FR47
TASK 25-55-11-000-002-A	Removal of the Ceiling Panels in the Aft Cargo-Compartment - FR47/FR59
TASK 25-55-11-000-003-A	Removal of the Sidewall Panels in the Aft Cargo Compartment - FR47/FR59
TASK 25-55-12-000-001-A	Removal of the Aft Cargo-Compartment Partition at FR65
TASK 25-55-12-000-002-A	Removal of the Ceiling Panels in the Aft Cargo Compartment at FR59/FR65
TASK 25-55-12-000-003-A	Removal of the Sidewall Panels in the Aft Cargo Compartment - FR59/FR65
TASK 52-30-00-860-001-A	Open the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
TASK 52-41-00-010-002-A	Open the Avionics Compartment Doors for Access
TASK 53-00-00-000-801-A	Removal of the Floor Panels in the Cabin from FR12 to FR70
TASK 53-00-00-000-801-A-01	Removal of the Floor Panels in the Cabin from FR12 to FR70 (Alternative Removal Procedure - Dry Sealing Concept)
TASK 53-00-00-000-801-A-02	Removal of the Cabin Floor Panels from FR12 to FR70 (Alternative Removal Procedure with the Skyflex Option)
TASK 53-12-13-000-001-A	Removal of the avionics compartment floor panels
TASK 06-41-53-00	FUSELAGE-DESCRIPTION AND OPERATION
TASK 21-21-00-00	AIR DISTRIBUTION AND RECIRCULATION - DESCRIPTION AND OPERATION
Distribution Ducts Location
Examples of Distribution Duct Connections
Examples of Distribution Duct Attachment Methods

3. Job Set-up
Subtask 21-20-00-861-050-A

A. Energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-861-002).

Subtask 21-20-00-865-050-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
122VU	AIR COND/RECIRC FAN/R/SPLY	3HG	W18
122VU	AIR COND/RECIRC FAN/L/SPLY	1HG	X18

Subtask 21-20-00-941-050-A

C. Safety Precautions
(1) On the panel 30VU:
(a) Make sure that:

the APU BLEED pushbutton switch is in the off position (the ON legend is off) and,
the ENG 1 BLEED and the ENG 2 BLEED pushbutton switches are in the off position (the OFF legends are on).

(b) Put a warning notice in position to tell persons not to operate these pushbutton switches.
(2) On the HP and the LP ground connector put a warning notice in position to tell persons not to supply the ground air.

Subtask 21-20-00-010-050-A

D. Get Access
(1) For the cockpit area supply and ventilation ducts:
(a) Get access to the cockpit.
(b) For the location of the ventilation ducts in the cockpit, refer to (Ref. AMM D/O 21-21-00-00).
(c) For the location of the applicable cockpit panel, refer to (Ref. AMM D/O 06-41-53-00).
(d) Remove the access panels as necessary (Ref. AMM TASK 25-13-41-000-001).

(2) For the cockpit riser duct on the LH side at FR13:
(a) Remove the lavatory (Ref. AMM TASK 25-41-41-000-001).
(b) Remove the ceiling panel 221AC as necessary (Ref. AMM TASK 25-23-42-000-001).

(3) For the supply and ventilation ducts in the avionics compartment:
(a) Put an ACCESS PLATFORM 2M (6 FT) in position at access door 824 and access door 811.
(b) Open the access door 824 and 811 (Ref. AMM TASK 52-41-00-010-002).
(c) For the location of the applicable access panel, refer to (Ref. AMM D/O 06-41-53-00).
(d) Remove the access panels as necessary (Ref. AMM TASK 53-12-13-000-001).

(4) For the cabin area supply and the cargo-compartment ventilation ducts in the FWD cargo compartment area:

Distribution Ducts Location

(a) Put the ACCESS PLATFORM 2M (6 FT) in position at the FWD cargo-compartment door 825.
(b) Open the FWD cargo-compartment door 825 (Ref. AMM TASK 52-30-00-860-001).
(c) Remove the access panels as necessary (Ref. AMM TASK 25-54-12-000-001), (Ref. AMM TASK 25-54-12-000-002) or (Ref. AMM TASK 25-54-12-000-003).

(5) For the cabin area supply ducts in the MID cabin and the wing box area:
(a) Remove the cabin floor panels as necessary (Ref. AMM TASK 53-00-00-000-801).
(6) For the cabin area supply and the cargo-compartment ventilation ducts in the AFT cargo compartment area:
(a) Put the ACCESS PLATFORM 2M (6 FT) in position at the AFT cargo-compartment door 826.
(b) Open the AFT cargo-compartment door 826 (Ref. AMM TASK 52-30-00-860-001).
(c) Remove the access panels as necessary (Ref. AMM TASK 25-55-11-000-001), (Ref. AMM TASK 25-55-11-000-002), (Ref. AMM TASK 25-55-11-000-003), (Ref. AMM TASK 25-55-12-000-001), (Ref. AMM TASK 25-55-12-000-002) or (Ref. AMM TASK 25-55-12-000-003) .

(7) For the riser ducts in the cabin area:
(a) Remove the upper and the lower sidewall panels as necessary (Ref. AMM TASK 25-23-44-000-001) and (Ref. AMM TASK 25-23-43-000-001).

4. Procedure
Subtask 21-20-00-020-050-A

A. Removal of an Air-Conditioning Distribution Duct
(1) Applicable on duct connection method:

Examples of Distribution Duct Connections

(a) Remove the clamps (2) and the bellows (3) or,
(b) Remove the nuts (4), the screws (6) and the seal (5) or,
(c) Remove the clamp (2) and the hose (10) or,
(d) Remove the clamps (2) and the sleeve (8).
(2) Applicable on duct attachment method:

Examples of Distribution Duct Attachment Methods

(a) Remove the screws (20), the washers (21) and the duct (1).
(b) Remove the clamp (22) and the duct (1).
(3) Where applicable make identification marks on the restrictors (9) and their positions in the duct (1).

NOTE: This will assist in the correct position of the restrictors on installation.

(4) Put protective covers on the open ends of the ducts and the related connections.

[Rev.10 from 2021] 2026.04.01 04:54:37 UTC