Mark, That is very helpful. What you describe with your voltmeter fits in
exactly with my ammeter findings. I will replace the regulator and expect to
cure the problem. In our situation we could measure the drain on the
battery, and having turned off everything except the radio and the fuel pump
this amounted to 3 amps with a topped up 16 amp/hours battery I reckoned
this gave us 5 hrs flying probably and certainly at least enough time to
complete a 20 min sea crossing. I am copying this to the list as I suspect
we won't be the last to have such a problem.
Regards, David
---- Original Message -----
From: "Mark Chetwynd-Talbot" <markt@avnet.co.uk>
Subject: Your 914 Rectifier problem
Dear David, (Replying off list)
I have been flying my 914 Trigear for about 200 hours over about 5
years. (Not much.) I recently had what sounds like exactly the same
problem as you describe. In my case I only have a voltmeter and I
noticed during a 1 hour trip from Wiltshire to North Yorks that the
reading started to fall below 12 volts. Over a period of about 30
minutes it continued to fall and I started to switch a few things off. I
really wanted to try to establish what was happening and I was not
particularly worried about possibly having to divert etc. It seemed that
for some reason the battery was no longer being charged. Then items like
the Skymap cut out when the voltage fell below 10 volts. The radio
signal became weak and distorted and the transponder ceased to function.
By the time I reached my destination (Wombleton) the flaps would only
come down extremely slowly!
As I had only very recently replaced the battery I asked Nev what he
thought was the likely problem. Without hesitation he said it was almost
certainly the regulator, which apparently has a reputation for
unreliability. We replaced it with a new one from Skydrive and
everything was right immediately.
Nev believes that the regulator probably gets 'cooked' if it is mounted
where mine is on the firewall. He is going to make up a new loom so that
we can move it to a position where it can be blasted with cool air near
the oil cooler.
It was not pleasant watching the volts dribbling away, I must admit. And
I was very glad that I was not on a long sea crossing! What I really
wanted to know - but did not discover - was the point at which the fuel
pump would cease to function!
Good luck.
Mark
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