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.

 

[shawnd]

After a few iterations with the design, the test panel has arrived. The CB panel markings still need a revision (it will be rounded and separate sections instead of the solid lines and one big blob). You can also see the new switches fitted on the test panel. It might be a bit big if you are comparing to the ETA rockers, but looks nice after looking at a M20V panel at the factory.  The avionics shop is also making quicker progress than I expected. Firewall front is done and looks great - luckily they also believe in functionality and clean looking result when it comes to their work.  My turn to pick up the pace and finish the seat and wall panels that AirTex shipped and then on to interior panel repair. Enjoy the pictures:

 

 

 

[shawnd]

Another update: avionics work is in full swing, got slightly delayed by panel design/proof/finalize work but here it is:

and a test fit of switches - love the attention to wiring: