Removal of the Avionics Equipment Blowing-Duct

TASK 21-26-42-000-802-A
Removal of the Avionics Equipment Blowing-Duct

CAUTION: USE ONLY THE GROUND SERVICE NETWORK TO SUPPLY ELECTRICITY BECAUSE THE AVIONICS VENTILATION SYSTEM IS NOT SERVICEABLE. IF YOU ENERGIZE THE AIRCRAFT ELECTRICAL CIRCUITS WITHOUT THE VENTILATION SYSTEM YOU WILL CAUSE DAMAGE TO ELECTRICAL EQUIPMENT.

ZONE: 120
ZONE: 130

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 2M (6 FT) - ADJUSTABLE
No specific	AR	PLUG - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
120	AVIONICS COMPARTMENT
130	FWD CARGO COMPT AFT BULKHEAD OF AVNCS COMPT TO FWD PRESSURE BULKHEAD OF WING CENTER BOX
131CW, 131DW, 131GW, 131HW

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 25-54-11-000-001-A	Removal of the Forward Cargo-Compartment Partition FR24A
TASK 25-54-12-000-003-A	Removal of the Sidewall Panels in the Forward Cargo Compartment
TASK 52-30-00-860-001-A	Open the FWD or Aft Cargo-Compartment Door with the Yellow Electric Pump
Avionics Equipment Blowing-Duct

3. Job Set-up
Subtask 21-26-42-861-061-A

A. Energize the ground service network
(Ref. AMM TASK 24-42-00-861-001).

Subtask 21-26-42-941-056-A

B. Safety Precautions
(1) On AIR COND panel 30VU:
(a) Make sure that the APU BLEED, all ENG BLEED and the PACK 1(2) pushbutton switches are released.
(b) Put a WARNING NOTICE(S) in position to tell persons not to operate these pushbutton switches.
(2) On the HP and the LP ground connectors, put a WARNING NOTICE(S) in position to tell persons not to supply the ground air sources.

Subtask 21-26-42-865-062-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AIR COND/AVNCS VENT/CTL	6HQ	D06
49VU	AIR COND/AVNCS VENT/CTL	5HQ	D05
122VU	AIR COND/AVNCS/VENT/MONG	3HQ	Y17
** ON A/C NOT FOR ALL
123VU	AVNCS VENT/EXTC/FAN	2HQ	AE02
** ON A/C ALL
123VU	AVNCS VENT/BLOWER/FAN	1HQ	AD10
** ON A/C NOT FOR ALL
123VU	AVNCS VENT/EXTC/FAN	2HQ	AC04

Subtask 21-26-42-010-065-A

D. Get Access
(1) Put an ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position below the forward cargo-compartment door.
(2) Open the forward cargo-compartment door (Ref. AMM TASK 52-30-00-860-001).
(3) Remove forward cargo-compartment partition-panels 131CW and 131DW (Ref. AMM TASK 25-54-11-000-001).
(4) Remove forward cargo-compartment sidewall-panels 131GW and 131HW (Ref. AMM TASK 25-54-12-000-003).

4. Procedure
Subtask 21-26-42-020-060-A

A. Removal of the Avionics Equipment Blowing-Duct
(1) Remove the clamps (3), (5) and (7).
(2) Move the flexible sleeves (6) to disengage the duct (2).
(3) Remove the duct (2).
(4) Remove the flexible sleeves (6) from the ducts (1) and (4).
(5) Put the PLUG-BLANKING in each disconnected line end.

[Rev.10 from 2021] 2026.04.02 06:11:05 UTC