Flickering ignition light

[pudestcon]

I have a red 'ignition' light on the instrument panel of my Thruster, it lights up when the master switch is turned on and gives a steady red glow. When the electric fuel pump switch is activated it causes the red light to flicker. Can anyone tell me how to overcome this, and is it a problem? I'm inclined to leave it as is, if not a problem, as a very visual reminder that the electric fuel pump is on.

 

Any thoughts are appreciated.

 

Pud

 

 

[Yenn]

What sort of ignition system are you using?

 

 

[turboplanner]

As per Yenn, but possibly an earthing problem.

 

 

[pudestcon]

What sort of ignition system are you using?

Weelll, Basically there is a lead from the battery + terminal through a fuse to the master switch, this then feeds a few gauges and to the fuel pump switch as well. From there to the pump and back to an earthing point on the frame. The gauges all earth back to a different earth point on the frame

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Pud

 

 

[Guest Andys@coffs]

In this case relatively simple to test for poor earth by getting an old analogue multimeter and measuring the voltage between the earth that is being used and the negative battery terminal on the battery. If the earth is OK then there will be almost no voltage. If its not OK then you'll get a flicker or a steady DC voltage. To test go initially to the scale that will show 12 v near as possible to full scale deflection and work downward. If you get to less than say 0.3v full scale and cant see anything then dont go looking any further. (PS all that pressumes a check with engine off and then another with it on)

 

This may not work with a digital meter as they dont show transients anywhere as well as the old meters did, you may never have seen the actual transient voltage peak on the analogue meter but the speed with which the needle took off gave you an indication if it was a significant spike or not.. on the digital depending on the variation with vibration you may see somethin or nothing....

 

Bottom line if you do see something above 0.3v then do something about it. In fact try for even less than that if possible......

 

Andy

 

BTW this wont show all possible issues, but given that you can see the flicker on the bulb it will be fine....Where faster transients are an issue which a meter cant show an oscilloscope can be used for the same thing as you play with the various connections around the aircraft to try and work out what is moving and creating issues