From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: Update on EMI problem.
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Date: Wed, 15 Jan 2020 21:50:17 -0500
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Not sure what an autopilot panel is, but did you disturb any wiring, 
grounds, etc?

Created a ground loop?

Any way you could (easily) restore things to the way they were -- just 
for testing purposes?

I just had a thought on the caps on the MAO sensors. I wonder if the 
purpose of those is not for EMI suppression, but rather to smooth out 
any pressure pulses from intake ports opening/closing (and/or RAM air 
pulses from prop). I remember seeing a vacuum filter in the line from 
the manifold to the EC in Tracy's RV-4.

Finn

On 1/15/2020 5:32 PM, Stephen Izett stephen.izett@gmail.com wrote:
> The symptoms in the EC2 and EFIS began after installing a couple of new Auto Pilot panels.
> Steve
>
>> On 16 Jan 2020, at 4:47 am, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:
>>
>> A ground issue somewhere. At battery, ground buss, ground strap to engine, ...
>> Corrosion or a loose bolt/nut.
>>
>> Just guessing. But if it used to work and no changes were made before the symptoms appeared...
>>
>> Yes, I know, easy to second guess the approach of someone else. :-)
>>
>> Finn
>>
>> On 1/15/2020 10:00 AM, Stephen Izett stephen.izett@gmail.com wrote:
>>> Hi Bobby
>>>
>>> I had no symptoms in the engine on tx until the last few weeks and only on controller A.
>>> It misses as the mixture goes very lean.
>>> In looking at the engine miss I realised the vertical speed was jumping on tx.
>>> Not sure what brought about the change that started the symptoms.
>>>
>>> Steve
>>>
>>>> On 15 Jan 2020, at 10:33 pm, Bobby J. Hughes bhughes@qnsi.net <flyrotary@lancaironline.net> wrote:
>>>>
>>>> Steve,
>>>>   I don’t recall if you are just seeing odd instrument readings or actual engine changes when you key the mic. At idle and ground ops I could almost kill my engine when transmitting on an SL30. The capacitors eliminated 90% of that problem. When I swapped the SL30 for a 430W it improved a little more.
>>>>   Bobby
>>>>       From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
>>>> Sent: Wednesday, January 15, 2020 8:06 AM
>>>> To: Rotary motors in aircraft
>>>> Subject: [FlyRotary] Re: Update on EMI problem.
>>>>   Hi Finn
>>>>
>>>> I only went for them as I understood others had suffered a similar symptom and this was Tracy’s recommended fix.
>>>> I’ve got more ferrites coming and I’ll be putting these on all inputs to the EC2 and ADHARS and at the feed point of the antenna.
>>>> I’ll feedback what I discover.
>>>>
>>>> Cheers
>>>> Steve
>>>>
>>>>> On 15 Jan 2020, at 9:02 pm, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:
>>>>>
>>>>> Did you trace the circuit? Any chance there's already caps on the board on your version of the EC2?
>>>>>
>>>>> Again, I don't see the need for the caps. Especially because your problem was only with controller A.
>>>>>
>>>>> I would start with temp input or serial input.
>>>>>
>>>>> Finn
>>>>>
>>>>> On 1/14/2020 11:23 PM, Stephen Izett stephen.izett@gmail.com wrote:
>>>>>> A frustrating few hours
>>>>>>
>>>>>> I got down to the hanger this morning to look into the EMI in both the engine controller and EFIS.
>>>>>>
>>>>>> First thing I did was reroute the radio coax so that instead of being in close proximity to many cables down the centre of the aeroplane instead down the very right hand side.
>>>>>> This increased the distance to various wire looms by ~450mm.
>>>>>>
>>>>>> Prior to this change the symptom outside the hangar was from memory about a 300ft/min vertical speed on tx in the Skyview EFIS.
>>>>>>
>>>>>> First test with radio tx after the reroute of coax inside the hangar yielded a "4 times worse" symptom in the EFIS! ~1300ft/min reading on tx.
>>>>>>
>>>>>> I then tried the test outside and away from the metal hangar by 10m and the symptom was reduced to ~600ft/min and increase in symptoms of about 100% on original problem.
>>>>>> I then applied a clamp on ferrite to the cable loom entering the ADHARS unit from where the symptom originates.
>>>>>> On tx outside the hangar again the symptoms are far reduced by over 1/2.
>>>>>>
>>>>>> So if I had left the radio coax where it was, the ferrite may have fixed the problem in the EFIS.
>>>>>> I have more ferrites on order and they appear to be very effective, so will use these to attenuate the RF entering the various pieces of equipment.
>>>>>> EMI trouble shooting is indeed a black art!!
>>>>>>
>>>>>> I also removed the Engine Control unit and soldered 0.1uF ceramics across the outputs to earth of the MAP sensors of both A and B computers as specified by Tracy.
>>>>>> On reinstalling the Engine Control unit I was not able to start the engine!
>>>>>> It would fire but not run on either controller.
>>>>>> So spark and fuel are present, but not to remain running.
>>>>>>
>>>>>> So the mod appears to have messed up the MAP sensing.
>>>>>> My initial thought was that the caps were actually resistors packaged wrongly but they measure open circuit.
>>>>>>
>>>>>> So the few hours of mods and testing has been exceedingly frustrating, going backwards at every turn except for the 1 ferrite showing itself to be very effective.
>>>>>>
>>>>>> I’m hoping my next outing will be very much more fruitful.
>>>>>> In the mean time I’ll ponder what could possibly cause both Computers in the Engine Controller to be u/s.
>>>>>> If I cannot discover my deliberate mistake. I’ll remove the caps and retest the Controller on Friday.
>>>>>>
>>>>>> Cheers
>>>>>>
>>>>>> Steve
>>>>>>
>>>>>>
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