Standby Horizon Indicator Information not Accurate

TASK 34-22-00-810-803-A
Standby Horizon Indicator Information not Accurate

1. Possible Causes

IND-STANDBY HORIZON [7FN]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 34-22-24-000-001	Removal of the Standby Horizon Indicator
AMM 34-22-24-400-001	Installation of the Standby Horizon Indicator

3. Fault Confirmation
Subtask 34-22-00-710-053-A ** ON A/C NOT FOR ALL

A. Test
(1) Not applicable, the fault is evident.

4. Fault Isolation
Subtask 34-22-00-810-053-A ** ON A/C NOT FOR ALL

A. Do the procedure that follows:
(1) After the aircraft stayed stable on ground for many minutes, make sure that the indications of the standby horizon indicator are in the tolerances that follow:

Roll: 0 deg. +/- 2.5 deg. (equivalent to 1/4 of a roll graduation)
Pitch: 0 deg. +/- 2.5 deg. (equivalent to 1/2 of a pitch graduation).

(2) If the indications are out tolerances, replace the IND-STANDBY HORIZON [7FN] , AMM 34-22-24-000-001 and AMM 34-22-24-400-001.

NOTE: After a long low-rate turn with a bank angle of less than 10 degrees (holding pattern, for example), it is possible that the standby horizon bank-angle indication will not be accurate immediately. A period of as much as three minutes after the turn can be necessary to get an accurate indication again. The same remark can be done for the pitch: if the aircraft stays stabilized for many minutes at a given pitch, then the standby horizon indicator will think that the vertical apparent axis is incorrect and will give an inaccurate pitch indication.
If such conditions are reported in the logbook, but on the ground the standby horizon indication is in the tolerances, it is not necessary to remove the standby horizon indicator.

[Rev.8 from Aug 2018] 2026.04.04 04:32:55 UTC