From: "Andrew Martin andrew@martinag.com.au" <flyrotary@lancaironline.net>
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Date: Mon, 6 Jan 2020 11:18:08 +0800
Message-ID: <CAJxaVD1zwEgikePHx88XS+ACA+rpdshM5Aj-qzkwNT386oUpkA@mail.gmail.com>
Subject: Re: [FlyRotary] Gremlin Search
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Hi Steve
I feel your pain, I had similar to your No.1 problem a few years ago, had
RF getting into CAS wire, was really hard to trace as only happened in
flight and scared the crap out of me every time I had to go up and test for
it, as motor would stop on each TX, ended up just being the quality of CAS
wire I used was not up to the job. I had tried all sorts of things prior to
this with no avail, replacing the CAS wire with industrial sized Beldon
shielded cable was a last ditch effort before completely rewiring the
plane, luckily it worked. Mixture was affected by the RX getting in the CAS
wire. I just cant remember if it was going extreme lean or rich as at that
stage I didn't have the wideband AFR gauge installed.

Andrew


On Mon, Jan 6, 2020 at 10:40 AM Stephen Izett stephen.izett@gmail.com <
flyrotary@lancaironline.net> wrote:

> Hi Guys
>
> I wonder if you guys have come across this fault or can help with my
> search for the culprit.
> Having made some alterations to our Dynon Skyview EFIS we went to fly onl=
y
> to have a problem and so aborted the flight.
> Previously the engine has been rock solid with none of the new symptoms.
> I have an Electronics/Communication systems background.
>
> The problem/symptoms:
>         1. During taxiing we noticed that every time we keyed the mic of
> the Garmin GTR225 we experienced significant mixture variations and
> stumbling of the Engine (Renesis 4 Port - EC2)
>         2. We then sought to clearly establish the symptoms and discovere=
d
> that along with the very repeatable interference to the Engine/EC2, the
> Skyview EFIS was also effected by tx. The vertical speed would go
> +250ft/min then -100ft/min on keying the mic.
>
> The changes we had made:
>         1. Changed the Pitch Autopilot Servo to a heavier duty unit (no
> wiring change)
>         2. Installed the Dynon Auto Pilot & Knob Panels - this meant a ne=
w
> connection to the the Skyview bus and shifting the trim control (inputs
> from sticks, Power and output to Electric Trim motor) from a relay deck t=
o
> the Dynon AP Panel (Build in trim controller).
>
> My thoughts are two fold:
> 1. RF getting into somewhere it shouldn=E2=80=99t. No changes have been m=
ade to
> the antenna or feed. However, I may have shifted some cables in close
> proximity to the antenna coax. I had just washed and left wet the Glasair=
's
> (fibreglass) vertical fin which has the 1/4 wave dipole antenna inside of
> it.
> 2. Earthing issues. There were no changes to the Earth system.
>
> Path forward:
> 1. Replace antenna feed with dummy load to isolate RF while still drawing
> current from the GTR225. (Where to borrow a dummy load around here?)
> 2. Check wiring to see if it is apparent that some have shifted in
> relationship to the antenna coax.
> 3. Check Earth buss for good connections.
>
> I do recall hearing someone with a similar fault on an EC2/3 years ago.
>
> Would really appreciate your feedback. I have little experience with RF
> interference and its rectification(no pun intended).
>
> Sincerely
>
> Steve Izett
> Perth Western Australia - Glasair Super IIRG - Renesis 4 Port EC2 EM3 RD1=
C
>
>
>
>
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:
> http://mail.lancaironline.net:81/lists/flyrotary/List.html
>

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<div dir=3D"ltr"><div>Hi Steve</div><div>I feel your pain, I had similar to=
 your No.1 problem a few years ago, had RF getting into CAS wire, was reall=
y hard to trace as only happened in flight and scared the crap out of me ev=
ery time I had to go up and test for it, as motor would stop on each TX, en=
ded up just being the quality of CAS wire I used was not up to the job. I h=
ad tried all sorts of things prior to this with no avail, replacing the CAS=
 wire with industrial sized Beldon shielded cable was a last ditch effort b=
efore completely rewiring the plane, luckily it worked. Mixture was affecte=
d by the RX getting in the CAS wire. I just cant remember if it was going e=
xtreme lean or rich as at that stage I didn&#39;t have the wideband AFR gau=
ge installed.<br></div><div><div><div dir=3D"ltr" class=3D"gmail_signature"=
 data-smartmail=3D"gmail_signature"><div dir=3D"ltr"><div><div dir=3D"ltr">=
<br><div>Andrew<br></div><div><br><br></div></div></div></div></div></div><=
br></div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gma=
il_attr">On Mon, Jan 6, 2020 at 10:40 AM Stephen Izett <a href=3D"mailto:st=
ephen.izett@gmail.com">stephen.izett@gmail.com</a> &lt;<a href=3D"mailto:fl=
yrotary@lancaironline.net">flyrotary@lancaironline.net</a>&gt; wrote:<br></=
div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bor=
der-left:1px solid rgb(204,204,204);padding-left:1ex">Hi Guys<br>
<br>
I wonder if you guys have come across this fault or can help with my search=
 for the culprit.<br>
Having made some alterations to our Dynon Skyview EFIS we went to fly only =
to have a problem and so aborted the flight.<br>
Previously the engine has been rock solid with none of the new symptoms.<br=
>
I have an Electronics/Communication systems background.<br>
<br>
The problem/symptoms:<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 1. During taxiing we noticed that every time we=
 keyed the mic of the Garmin GTR225 we experienced significant mixture vari=
ations and stumbling of the Engine (Renesis 4 Port - EC2)<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 2. We then sought to clearly establish the symp=
toms and discovered that along with the very repeatable interference to the=
 Engine/EC2, the Skyview EFIS was also effected by tx. The vertical speed w=
ould go +250ft/min then -100ft/min on keying the mic.<br>
<br>
The changes we had made:<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 1. Changed the Pitch Autopilot Servo to a heavi=
er duty unit (no wiring change)<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 2. Installed the Dynon Auto Pilot &amp; Knob Pa=
nels - this meant a new connection to the the Skyview bus and shifting the =
trim control (inputs from sticks, Power and output to Electric Trim motor) =
from a relay deck to the Dynon AP Panel (Build in trim controller).<br>
<br>
My thoughts are two fold:<br>
1. RF getting into somewhere it shouldn=E2=80=99t. No changes have been mad=
e to the antenna or feed. However, I may have shifted some cables in close =
proximity to the antenna coax. I had just washed and left wet the Glasair&#=
39;s (fibreglass) vertical fin which has the 1/4 wave dipole antenna inside=
 of it.<br>
2. Earthing issues. There were no changes to the Earth system.<br>
<br>
Path forward:<br>
1. Replace antenna feed with dummy load to isolate RF while still drawing c=
urrent from the GTR225. (Where to borrow a dummy load around here?)<br>
2. Check wiring to see if it is apparent that some have shifted in relation=
ship to the antenna coax.<br>
3. Check Earth buss for good connections.<br>
<br>
I do recall hearing someone with a similar fault on an EC2/3 years ago.<br>
<br>
Would really appreciate your feedback. I have little experience with RF int=
erference and its rectification(no pun intended). <br>
<br>
Sincerely<br>
<br>
Steve Izett<br>
Perth Western Australia - Glasair Super IIRG - Renesis 4 Port EC2 EM3 RD1C<=
br>
<br>
<br>
<br>
<br>
--<br>
Homepage:=C2=A0 <a href=3D"http://www.flyrotary.com/" rel=3D"noreferrer" ta=
rget=3D"_blank">http://www.flyrotary.com/</a><br>
Archive and UnSub:=C2=A0 =C2=A0<a href=3D"http://mail.lancaironline.net:81/=
lists/flyrotary/List.html" rel=3D"noreferrer" target=3D"_blank">http://mail=
.lancaironline.net:81/lists/flyrotary/List.html</a><br>
</blockquote></div>

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