Because the ADI is the primary attitude and heading reference, losing it will force you to alter your
instrument scan pattern significantly. You will have to include the standby AI and devote more time to the
The first and most important step in dealing with an ADI failure is to establish an attitude reference on the
standby gyro. The remainder of the procedure is also important, but this step is vital. See the Partial
Panel section of this FTI for further information.
Figure 43 shows one of the possible indications of a failed ADI. Remember that the OFF flag does not
have to be present for the indicator to give false readings; the flag only indicates the status of electrical
power, SAHRS validity signals, and internal error detection circuitry. Most of the time you will be able to
detect and ADI failure from outside references, but in IMC conditions, uncommanded changes in heading
and attitude indications may be your tip-off that the ADI has failed.
The procedure for dealing with an ADI failure is:
Use the standby attitude indicator (AI) for
Use the HSI for your primary heading
Maintain VFR conditions, if possible.
-33 -34 -35 -N - 1 - 2 - 3 -
Check the electrical system.
Report the instrument failure to ATC.
Watch for possible progressive failure of
the SAHRS system.
Land as soon as practicable.
TURN AND SLIP INDICATOR FAILURE
In the event that the turn needle fails, you will
have to use bank angle and airspeed for 1/2
Figure 43: FAILED ADI
standard and standard rate turns. Be aware that
the turn indicator is an integral part of the ADI, so
even though it has its own power source, its failure may indicate other ADI problems.
There is no specific procedure for a slip indicator malfunction because it is unlikely to fail unless it is
physically damaged and because it does not serve an important enough function to warrant any remedial
The procedure for dealing with a turn and slip indicator failure is:
Check the ADI for correct indications.
Beware of possible electrical problems.
Use the ADI and airspeed for turn rate reference.