(2022) Service Alert 2182 Rev B: Dual GI 275 simultaneous “AHRS Align” message in flight

REVISION B:

Corrected Products Affected and Resolution

PRODUCTS AFFECTED:

GI 275 installations with Expansion Board software version 2.42 or earlier, in the dual-ADAHRS configuration in aircraft with non-redundant or single-source pitot systems are affected. (See Service Alert linked below for instructions on how to view the Expansion Board software version.)

ISSUE:

If the aircraft’s pitot tube becomes obstructed due to the pitot tube cover being left on, icing blockage, and/or other debris obstruction, the GI 275 airspeed input can be interrupted. This interruption may cause both GI 275 units to enter alignment mode during certain maneuvers. If this occurs, it will result in the temporary loss of all attitude information from both GI 275 units.

PILOT ACTION:

If the GI 275 dual-AHRS configuration is the only source of attitude in an aircraft without a redundant pitot source, do not fly in instrument meteorological conditions.

If the GI 275 Attitude display enters alignment mode during flight, when appropriate, establish wings level (stable flight with assumed bank angles less than 5 degrees) to allow the units to realign and recover attitude display.

RESOLUTION:

This issue will be resolved with the incorporation of STC Service Bulletin 22002, which authorizes the installation of GI 275 Software Version 2.43. This service bulletin is available and is considered mandatory for installations with no tertiary source of attitude information and no redundant source of pitot pressure.