Systems - ADIRU

Question 1

When would the ON BAT light illuminate?

Answer 1

When the ADIRU is ON but subsequent electrical power was removed and the BAT switch turned off

Question 2

If the ON BAT light is on, what else is an indication of ADIRU being used by the battery?

Answer 2

Horn going off in the Nose Wheel well

Question 3

When can the ADIRU be turned off?

Answer 3

Only on the ground No, below 30kts, never in flight per system logic

Question 4

Can you still navigate without ADIRU?

Answer 4

Only to the fixes stored in the FMC previously. No LNAV/VNAV FPV no envelope protections

Question 5

How can you navigate without ADIRU?

Answer 5

Use HDG SEL after you update it.

Question 6

What bus powers ADIRU?

Answer 6

Main BAT HOT BUS

Question 7

If ADIRU fails, what will SAARU provide?

Answer 7

Only data derived from the air data modules, no inertial navigation

Question 8

What devices are inside the ADIRU?

Answer 8

Ring laser gyro’s, linear accelerometers and input processors

Question 9

What components make up the ADIRS?

Answer 9

• ADMs
• ADIRU
• SAARU

Question 10

What kind of information is provided by ADIRU?

Answer 10

Primary flight data, air data and inertial reference

Question 11

How will you update the heading information to the SAARU?

Answer 11

Type in mag compass heading initially and then periodically after that.

Question 12

With a SAARU-only operation, where will attitude reference be found? Or how do you know that the SAARU is healthy?

Answer 12

Under SAARU only operation attitude reference will remain displayed on PFD’s and you can crosscheck the values with the STBY flight instruments display

Question 13

How will a SAARU-only operation affect Class II Navigation or over-water operations?

Answer 13

Since you have lost all navigational performance you must exit MNPS/OTS routing.

Question 14

If ADIRU fails with GPS operational how do the PFD or ND look/display?

Answer 14

• ND will display orientation changes from HDG UP to TRK UP, ND wind direction/speed and arrow missing
• PFD will be missing flap maneuvering speeds
• AFDS modes not available are LNAV/VNAV, TOGA, LOC, GS, FPA, TRK HLD/HDG SEL (HDG available to regain autopilot after it is updated in the FMC)
• ADDITIONAL ITEMS such as autobrakes, FMC VNAV pages, FMC PERF prediction pages

Question 15

If ADIRU fails and GPS is not operational, what additional items are inoperative?

Answer 15

ND MAP mode, active leg course and distance, direct to waypoint function, ALTN PG divert now function, navigation radio autotuning function

Question 16

How long does it take for ADIRU to align?

Answer 16

6-15 minutes depending on where you are located in the world or if your plane has been moved during alignment

Question 17

How do you align ADIRU?

Answer 17

Turn it off for 30 seconds, then on, put in a reference position in the FMC and wait

Question 18

How often should ADIRU be reset according to Boeing?

Answer 18

Once every 24 hours

Question 19

What happens if the aircraft is moved during the alignment process?

Answer 19

FMC MSG will be generated, must begin the realignment process again

Question 20

How long will the SAARU provide heading information following an ADIRU failure?

Answer 20

Initially for 3 minutes, after must update periodically

Question 21

With any EICAS message, how will you find additional information regarding the malfunction?

Answer 21

STATUS page or SYS synoptic pages

Question 22

On initial power up what mode does ADIRU start up in?

Answer 22

Align mode

Question 23

Is there an EICAS message?

Answer 23

MEMO MSG and time to remain on ND

Question 24

How can you tell if the GPS is Updating the FMC?

Answer 24

ND has green GPS(3) also POS REF PG in the FMC

Question 25

How do you power-up the SAARU?

Answer 25

You cannot, no controls whatsoever