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ADIRU "ON BAT" light

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Load up a cold and dark panel or shut down your plane normally. This means that your ADIRU switch should be in "OFF" position.

 

With all power removed (on board, external disconnected, and battery power switched off), push the ADIRU switch. The "ON BAT" light comes on with the infamous battery siren.

 

According to the FCOM: "The ON BAT light illuminates when the ADIRU switch is selected ON and ground power or primary power is subsequently removed or failed (battery power only remains)."

 

This says that:

 

1. Without power and battery switched off, the ADIRU should not try to power up when switched on, and should not show ON BAT.

2. With the power intentionally removed, ie during powering down, the power has not failed and therefore should not trigger the ON BAT and alarm. 

 

For a similar example, try this on the NGX with the IRS. Yes, different plane, but same Boeing philosophy... I think.

 

Also, the FCOM describes the ON BAT light as illuminated white, while the PMDG's model shows green. But, this could be simply difference in aircraft blocks?

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  • Commercial Member

From the manual it states that the battery bus must be powered (BATTERY ON) before the ADIRUs can be switched ON.

 

Once the ADIRUs are ON, if the battery is switched OFF, the hot battery bus continues to supply power to the ADIRUs, and the horn sounds on the ground.

 

It is not possible to switch the ADIRUs OFF in flight.

 

Best regards,

Robin.

  • Author

 

 


Once the ADIRUs are ON, if the battery is switched OFF, the hot battery bus continues to supply power to the ADIRUs, and the horn sounds on the ground.

 

That's exactly what I'm saying. In PMDG, it *is* possible to activate the ADIRU light and alarm with the power and battery already off.

 

1. Power is off, push ADIRU on, light and alarm activate.

2. ADIRU is on, power is switched off, light and alarm activate.

3. Power is off, push ADIRU of, light and alarm do not activate.

 

In the real plane and according to the FCOM, the system follows condition 2 and 3. PMDG follows conditions 1 and 2.

 

Like I said, start a cold and dark panel and see what happens when you switch on the ADIRU before anything else, including power.

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  • 4 months later...

The ADIRU is on the hot battery bus, i.e. directly powered from the battery bus bypassing the battery on/off switch.

 

In the case that you turn off your battery switch and "forget" the ADIRU on, the alarm will sound to alert you to the fact that the battery is still supplying current to the ADIRU load - and will likely be depleted by the time you try to power up for your flight back home. :) 

 

This is a common power attachment for critical systems that need to be on when all else fails.  

  • Commercial Member

 

 


In the real plane and according to the FCOM, the system follows condition 2 and 3. PMDG follows conditions 1 and 2.

 

If you believe you've found a bug:

support.precisionmanuals.com

 

It's best just to go directly to them instead of the back and forth here if you actually believe it's a problem and not user error - particularly when an SP is on the horizon...

Kyle Rodgers

  • Author

If you believe you've found a bug:

support.precisionmanuals.com

 

It's best just to go directly to them instead of the back and forth here if you actually believe it's a problem and not user error - particularly when an SP is on the horizon...

Wow. I've completely forgotten about this thread.

 

Anyway, I'm sure they caught it by now.

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  • Commercial Member

 

 


Anyway, I'm sure they caught it by now.

 

I wouldn't assume.  Please submit a ticket.  Just because the thread has been here a while doesn't mean it's been seen by the people who matter.

Kyle Rodgers

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