Mailing List flyrotary@lancaironline.net Message #46042
From: Tracy Crook <tracy@rotaryaviation.com>
Sender: <rwstracy@gmail.com>
Subject: Re: [FlyRotary] Snubber was[FlyRotary] Re: Initial Engine Startup
Date: Thu, 7 May 2009 14:59:21 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Mike,  I looked up the program notes and you should be in good shape.  Everything updated after 4 - 1 - 07 looks like it has the snubber fix and your instructions indicate that the new Mode 2 is in as well.   The name snubber comes from any device that absorbs the energy produced by an inductor (a fuel injector in this case) when the current to it is switched off. 

Credit to Steve B. for putting the finger on this factor.

Tracy

On Thu, May 7, 2009 at 11:01 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:

Hi Mike,

 

Tracy gets busy as you can imagine, I’ll try to answer your question about the “snubber” fix.

 

Basically, it was discovered by a member of this list that the collapsing magnetic field of the injector coils were having a more significant effect on injector open time than first realized.  In short, the injector on time was not just that commanded by the EC2/3 but was also affected by this generated voltage of the collapsing field.  Since it was not a fixed thing (depending on several factors), it could make tuning a bit more of a hassle to tune – no danger of your engine quitting or anything drastic like that because you could compensate (to some extent) by your tuning and manual mixture control.  But, because the effect varied – tuning was not necessarily as easy and precise as  could be desired.

 

In any case, a fix to such excursions in other fields are known as “snubber” fixes – I presume because they “Snub” out the problem.  Tracy will generally automatically add the “snubber’’ fix the next time you have reason to send your EC2/3 in for an upgrade. 

 

I flew for years without the fix, so it is not something you have to do immediately, but should at some point.  You will likely need to retune your fuel map afterwards, so I would not spend a  LOT of time doing that at this point unless you do have the “Snubber” fix.

 

My 0.02 worth

 

Ed

 


From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mike Fontenot
Sent: Thursday, May 07, 2009 10:16 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Initial Engine Startup

 

Tracy,

You wrote:
>>What was the date of last update or service?  Might be able to tell about the snubber update from that.<<

Here is the update info for my EC2 / EM2 combo, which was in October 2007:

Looking at my manuals I see:

EC2 Manual: Model: EC2 . AD   Serial# 634    Date: 19-Oct-07   . On the first page of the manual, at the top it says:

RWS EC2-AD Suzuki-4 ENGINE CONTROLLER  10-17-07

Page 10 has the section: MODE 2 INJECTION DYNAMIC RANGE ADJUST

EM2 Manual: Model: EM2 . C3   Serial# 197   Date: 19-Oct-07

Am I Snubberfied? Has Snubberfication occurred. Is my system Snubberlicious?

I need coffee.

--
Mike

================================
Mike Fontenot
Apex Consulting & Services LLC
Lakewood, Colorado
303 / 731-6645
mikef AT apexconsultingservices DOT com
================================


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