(2011) Service Advisory 1156 Rev A: Potential GRS 77 and GRS 77H reset

AFFECTED PRODUCTS

This issue affects all G500/G500H/G600 systems, and all G900X, G950, G1000, G1000H, Cirrus Perspective™, and Embraer Prodigy® Integrated Flight Deck Systems with GRS 77 software versions 2.10 through 3.02 and GRS 77H software version 3.50.

DESCRIPTION

The GRS 77/77H may reset during sustained bank turns. The conditions that may initiate this reset occur when operating in regions where the earth’s magnetic field vector is close to vertical (e.g. northern Canada, northern Russia, and Antarctica). The reset may occur after 30 seconds of turning when bank angle exceeds 35 degrees and speed is greater than 150 knots.

If the reset occurs, it results in a temporary loss of attitude and heading, typically not lasting longer than 45 seconds.

PILOT ACTION

In the affected regions, refrain from operating at bank angles exceeding 35 degrees. Refer to the applicable Airplane Flight Manual, Airplane Flight Manual Supplement, or Rotorcraft Flight Manual Supplement for information regarding immediate actions in the event of any loss of attitude and/or heading information.

RESOLUTION

This issue will be corrected in a future software release.