Removal of the Integrated Standby Instrument System (ISIS) Indicator

TASK 34-22-25-000-001-A
Removal of the Integrated Standby Instrument System (ISIS) Indicator

NOTE: After long low-rate turns (less than 6 degree bank) the ISIS indicator does not give accurate bank indications immediately. The specification of the ISIS indicator accepts this type of operation. Thus, it is not necessary to replace the indicator.

ZONE: 211
FIN: 22FN ** ON A/C NOT FOR ALL

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	CAP - BLANKING
No specific	AR	PLUG - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
F1402369	1	EXTRACTING TOOL

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
211	COCKPIT

C. Referenced Information

REFERENCE	DESIGNATION
ISIS Indicator

3. Job Set-up
Subtask 34-22-25-865-058-A ** ON A/C NOT FOR ALL

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	NAV/STBY/INST	5FN	F12
105VU	NAV/STBY/INST/BAT	23FN	J01
122VU	LIGHTING/INSTL LT/MAIN INST/PNL AND/PED	4LF	Y04

Subtask 34-22-25-010-050-A ** ON A/C NOT FOR ALL

B. Remove the thermoformed cover from the center instrument panel.

Subtask 34-22-25-860-072-A ** ON A/C NOT FOR ALL

C. Aircraft Maintenance Configuration

NOTE: In this procedure, the screws are identified as the adjusting screws and the mounting screws.

The adjusting screws (3) are installed on the top right and bottom left corners of the ISIS indicator housing.
The mounting screws are installed on the top left and bottom right corners of the ISIS indicator housing.

(1) Before you remove the ISIS indicator, make sure that the two mounting screws that attach the clamp to the aircraft structure are installed as follows:

One in the top left corner, and
The other in the bottom right corner.

(a) Do not remove the two mounting screws during the removal of the ISIS indicator.

NOTE: If you remove the two mounting screws, the clamp that attach to the aircraft structure can go missing.

4. Procedure
Subtask 34-22-25-020-051-A ** ON A/C NOT FOR ALL

A. Removal of the ISIS Indicator (22FN)

ISIS Indicator ** ON A/C NOT FOR ALL

CAUTION: WHEN YOU REMOVE THE ISIS INDICATOR, DO NOT USE THE BARO BUTTON TO PULL THE INDICATOR OUT OF ITS HOUSING. IF YOU USE THE BARO BUTTON, YOU CAN CAUSE DAMAGE TO THE INDICATOR.

(1) Loosen the adjusting screws (3). Do not remove them.
(2) Push the adjusting screws (3) to release the ISIS indicator (1) from the clamp.
(3) Use the F1402369 EXTRACTING TOOL and disengage the ISIS indicator (1) from its housing.
(4) Disconnect the electrical connector (4).
(5) Disconnect the quick-disconnect couplings (2) from the connectors (5).
(6) Remove the ISIS indicator (1) from its housing.
(7) Put the CAP - BLANKING on the disconnected electrical connectors (4) and (6).
(8) Put the PLUG - BLANKING on the disconnected connectors (5) and the quick-disconnect couplings (2).

[Rev.10 from 2021] 2026.04.01 12:35:01 UTC