I have had a report from one of our UK Europa pilots that might be of
interest to others. His info and my comments are included below.
>>I am sure you will be pleased to hear that it appears the crowbar was
actually doing a good job and protecting my avionics and battery. The
crowbar was checked and given a clean bill of health, so I reinstalled
it. Since removing the crowbar, I have been monitoring the voltmeter
very carefully but I have never seen it go above 13,8V in flight.
However, when I started the engine after reinstalling the crowbar, the
volt meter recorded 16V at 3000 rpm. To cut a long storey short, I
changed the regulator for the original one (Bob Nuckolls suggested I
replaced it after I blew my capacitor when I first installed the
crowbar) and the voltage remained at 13.8V. So it looks like the
replacement regulator has developed an intermittent fault causing the
over-voltage I experienced in Germany. I will probably order another
regulator just in case it was weakened when I blew the capacitor.<<
I am sorry to hear that you are still having problems with your
electrical system. However it is gratifying to know that the crowbar
unit is doing its job. A continuous voltage of 16 volts would certainly
damage the battery. An occasional blip to that level would be no real
problem but I would want to get it fixed after returning to my home
airfield. As we discussed isolating the crowbar unit is acceptable as a
get you home measure provided that you do not get continuous high
voltages. If this happens during the return flight the generator should
be isolated from the rest of the system without delay (less than 20
minutes say). If this can be achieved by circuit breaker/switch
selection it would avoid an immediate diversion. It would then be a case
of minimising electrical load and monitoring battery voltage closely.
For bad weather or flights requiring system powered radio/GPS I would
not rely on a battery for more than 30 minutes (less if it is old or not
fully topped up before the failure). If the aircraft needed electrical
power for the engine to run (eg Subaru or 914 powered aircraft) a
diversion should be made to the nearest suitable airfield.
Nigel Charles
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