From Frustration to Flight: A Renewed Avionics Upgrade Journey for my 252

[shawnd]

Thanks folks, looks like this will be a fun exercise. Will report back findings.

[shawnd]

In parallel, trying to see if we have the annunciator be fully functional despite the changes to EIS. After reviewing the schematics, looks like only the fuel quantity might need some work. Analog output from fuel senders sends 0.1 to 4.7 V. Maybe the GEA-110 or GI-275 discrete outputs can provide this functionality to indicate low fuel. 

Color coded the annunciator lines for the schematics if anyone is interested.

 

ElectricalSchematics-AnnunciatorPanel.pdf

Update: persisted the example lines from the left fuel qty gauge to transmitter.

[Aerodon]

Nicely done with the color coding.  The annunciator is calibrated to trigger an alarm when the fuel reaches a low level.  A JPI EDM900 can be programmed to provide a low level alarm (to the red/yellow annunciator or a separate low fuel alarm).  I'm not sure if this is on the calculated low level or measured low level.

It look like the GI-275 can have a discrete out on reaching a measured low fuel level.  But the annunciator is not looking for a discrete in, its looking for a voltage or resistance below a certain level.

I'm going a different direction, replacing the annunciator panel with a series of Eaton annunciators.  Personally I think the Mooney low fuel at 2.5G is useless, I prefer an overall low level of 8-12G.  

Aerodon

 

 

 

 

 

[shawnd]

There might be methods such as using pull up / down resistors to do the trick as well. Not an electronics expert :-) The only output I really want to send the annunciator is that fuel qty is

1. state 1: empty or near empty (LOW)
2. state 2: not empty indicating enough fuel so we can send it HIGH of 5 V

The EIS will of course warn me correctly of approaching empty etc so I am not worried. But want to utilize the annunciator panel to the fullest.