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1. 10:03 PM - [Fw: Re: Re: 912ULS and XCOM760 Problem] (Silvano Gai)
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| Subject: | Re: 912ULS and XCOM760 Problem] |
FYI
-- Silvano
-------- Original Message --------
Subject: Re: RotaxEngines-List: Re: 912ULS and XCOM760 Problem
From: Michael Coates <info@xcomavionics.com>
CC:
References: <1191659095.m2f.138450@forums.matronics.com>
<4707C244.508@ip6.com>
Hello Silvano, thank you for forwarding on this information from the
Rotax group. I just tried to reply directly but because I am not a
member of this group it won't allow me even though I am a member of the
AeroElectric one ??.
If possible are you able to forward on this reply on my behalf ?.
Firstly, the Euro foxes have had a problem for a long time with
incorrect wiring which has been plaguing several of the dealers around
the world.
Euro Fox did not install the electrolytic capacitor which is a
requirement of the Rotax factory when using their regulator. Finally
the dealers that were having problems convinced euro Fox to install the
electrolytic capacitor but unfortunately they did not put it in the
right position so that was no protection in the circuit.
As mentioned above is a requirement of Rotax and I quote the
installation manual _"for flawless operation of the regulator and
electrolytic capacitor must be installed"_, basically what they are
saying is our regulator works "most" of the time but when it doesn't
work you must install and electrolytic capacitor to protect your
Avionics from damage. This is fine if it is installed in the correct
position but if it is not installed in the correct position it simply
will not work. The best option however is to replace the Rotax
regulator with the PowerMate regulator which has been offering faultless
performance for many of our customers for the last five or six years.
Please see the following link for our suggested method on wiring up a
typical light sport aircraft
http://www.mcp.com.au/xcom760/faq/wiring-aircraft.pdf
We receive a lot of feedback from customers that are having problems
with their radio and occasionally locking up, this is a direct result of
the radio going into safe mode after it has received voltage
irregularities, this could include voltage spikes such as over voltage
or also brownouts. An electrolytic capacitor fitted in the correct
position will eliminate this problem. The Euro Fox dealer in Australia
now fits the electrolytic capacitor in the correct position and no
longer has any problems whatsoever. We have customers with more than
1800 hrs flying behind the XCOM with Rotax 80 hp engines without any
problems at all but they have the electrolytic capacitor fitted in the
correct position.
With regards to the radio going into safe mode, what happens is if the
radio experiences any voltage irregularities it will go into safe mode
for approximately 30 seconds upon which it checks again and if
everything is fine and then restarts normal operation. During this
procedure the radio is still able to receive but it will not transmit
and none of the buttons will work hence the reported lock-up problem.
This is a concern to some of our customers so some time ago we
implemented a flashing screen where the screen turned on and off once
per second if the radio ever went into safe mode. Further to this we
have now added some additional parts to our radio to also help eliminate
the weaknesses with the Rotax regulator. The XCOM radio does however
exceed the required TSO DO-160 standards for voltage stability and it is
the Rotax regulator which is at fault in this case, because our radio is
used in many Rotax installations we have adapted our design to be more
stable when working with a Rotax regulator. (NOTE: There seems to be a
peak in Rotax regulator failures in the last four months based from
reports of the different dealers selling our product, so it may be that
Rotax is starting to have a problem with some of the new installations)
One of the things that can happen with a radio over time is that it can
be damaged by ongoing voltage instability or by high aerial VSWR and
that may be why you put a new radio in it starts working again but my
guess is that the same radio working now will probably not be working in
some 30 hour's time because it will go on to be damaged just like the
one you have just taken out.
Of note I spent all of last Thursday down with a large aircraft importer
and manufacturer who was having trouble with four XCOM radios that would
start out perfect and then deteriorate over five hours until they were
unusable and transmission was no longer being produced. Even though
they had reassured me a hundred times that the installation had been
checked out in every respect when I got there and put an antenna
analyser onto the aircraft it was shown the have and aerial VSWR of 7:1
!! and this explains the problems with transmission.
No radio can it be expected to last at more than 3:1. Fitting a new
aerial and grounding it correctly brought the VSWR down to under 2:1
across the entire aviation band and I expect that the radio will now go
on to perform faultlessly the many years to come.
I don't know the exact figure that I would say 99% of our service is
based around bad installation, incorrect materials used or simply lack
of knowledge by the aircraft owner who is trying to be a jack of all
trades and master of none as he builds his aircraft. We have radios
turn up the service that are reported as the intercom has failed. As
soon as we turn the radio on and adjust the intercom squelch from 63
which is as maximum value back down to a more sensible 20 the radio
suddenly works and it is normal for us to get two or three of this type
of " failure" each week. This is something we are addressing on our
website to try and educate our customers and as such have produced a
wealth of material for the standard home builder including some of the
following guides.....
Aerial dummies guide
http://www.mcp.com.au/xcom760/education/XCOM-Aerial-Dummies-Guide.pdf
How to make an aircraft harness
http://www.mcp.com.au/xcom760/education/education.html#Anchor-Ho-25294
How to terminate a BNC connector
http://www.mcp.com.au/xcom760/education/education.html#Anchor-Ho-10102
How to solder
http://www.mcp.com.au/xcom760/education/education.html#Anchor-Ho-63324
Etc, etc.....
Just reviewing the information in the e-mail again it is only necessary
to fit one electrolytic capacitor to an aircraft but it must be
installed in the correct position as per hour suggested layout and the
sport aircraft wiring guide
http://www.mcp.com.au/xcom760/faq/wiring-aircraft.pdf
As always we make ourselves available to any of our customers who are
having difficulties and most of the time these can be resolved over
e-mail by returning the radio to the factory defaults and checking the
installation which includes all of the harness wires and also the aerial
VSWR.
I often say to my customers it is a bit like buying a new TV and new
roof mounted TV aerial. It's easy to put the TV in the lounge room and
expect it to work but because you don't have the equipment to tell you
which direction you need to point the aerial to get the best reception
you will get very ordinarily reception at the best of times. Somebody
however with the correct equipment can point the aerial directly at the
tower within a few seconds and provide you with beautiful clear
results. It is the same with aircraft installations, the aerial has a
major effect on the installation as does the wiring harness, just like
the TV example above unless you have the aerial properly tuned in good
quality cable between the aerial and your new TV you will experience the
same frustration and poor results as you would in the aircraft.
As always, please come back to me with any additional questions you may
have so that we can personally assist our customers in getting the best
from their equipment. Kind regards Michael Coates XCOM Avionics
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