ADIRS

Question 1

ADIRS
Rotary Switch:
What are the positions? Describe their functions

Answer 1

Three positions:
-NAV Normal Ops
-ATT provides Only Attitude and Heading.
Heading must be updated every 10 min in MCDU.
-OFF shuts off both IR and ADR

Question 2

What are the two types of IR Faults:

Answer 2

• Flashing:
  Attitude and Heading can be recovered in ATT mode
• Solid: IR has failed

Question 3

ADIRS:
What does a Full Alignment do? How long does it take?

Answer 3

• Clears groundspeed and Drift
• Captures present position
• 7-10 minutes

Question 4

ADIRS Quick Alignment:
What does a quick alignment do?
How long does it take?

Answer 4

• Clears groundspeed only
• 30 seconds

Question 5

Why ADIRS are left in the ON position on the ground?

Answer 5

• They provide information to calculate fuel density during fueling.

Question 6

IRS only navigation (no GPS) in RNP airspace limitations:

Answer 6

Flight time outside of radio navaid coverage.
- 6.2 hrs from IRS ground alignment
- 5.7 hrs from last FM position update

Question 7

What happens when the ADIRS are on Battery power only?

Answer 7

• Horn will sound in the nose wheel well
  (Same horn as the APU fire horn)

Question 8

What is the Mix IRS position?

Answer 8

• FMGEC computes an average of the 3 IRS positions.
• If there is a dramatic difference in one position it will be factored in less than than the other two.

Question 9

Each FMGEC compares the mix IRS and mixed gps (GPIRS) .
The difference is?
How and what is this used for?

Answer 9

• The Bias
• Bias is constantly memorized by the system.
• If Radio or GPIRS is lost, the system will adjust the Mix IRS position using the bias for navigation.

Question 10

How many ADIRU’s

Answer 10

• 3

Question 11

What are the two parts of the ADIRU’S:

Answer 11

• ADR (Air Data reference): Baro, Airspeed, Mach, AoA, temp, and overspeed.
• IR (Inertial Reference): attitude, heading, flight path vector, accelerations, angular rates, ground speed, vertical speed, and aircraft position.