X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from rg4.comporium.net ([208.104.2.24] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTPS id 2386927 for flyrotary@lancaironline.net; Sun, 14 Oct 2007 23:11:52 -0400 Received-SPF: neutral receiver=logan.com; client-ip=208.104.2.24; envelope-from=Jewen@comporium.net Received: from 208-104-81-95.lnhe.2wcm.comporium.net (HELO engineer1) ([208.104.81.95]) by rg4.comporium.net (MOS 3.8.4-GA FastPath queued) with SMTP id AEH32749; Sun, 14 Oct 2007 23:11:15 -0400 (EDT) Message-ID: <002f01c80ed8$f195a4a0$6505a8c0@cooleygroup.local> From: "Joe Ewen" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: EC2 20B Injector Power Circuits Date: Sun, 14 Oct 2007 23:10:30 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002C_01C80EB7.6A781DC0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 X-Junkmail-Status: score=10/70, host=rg4.comporium.net X-Junkmail-SD-Raw: score=unknown, refid=str=0001.0A090204.4712DA53.0075,ss=1,fgs=0, ip=208.104.81.95, so=2007-03-13 10:31:19, dmn=5.4.3/2007-09-06 This is a multi-part message in MIME format. ------=_NextPart_000_002C_01C80EB7.6A781DC0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Al, Thanks for the feedback. Are there any other undocumented issues with = the 20B controller that I should know about? How did the painting touch = up work out? Thanks, Joe ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Sunday, October 14, 2007 9:41 PM Subject: [FlyRotary] Re: EC2 20B Injector Power Circuits Joe; You are right. We discovered this crossfeed issue some time back. Is = applies only to the 20B version as the 13B has separate drivers for each = set. Install Schottky diodes in the circuits for each injector. Tracy = is aware of this, and has installed the diodes in his as well. Al -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Joe Ewen Sent: Sunday, October 14, 2007 3:20 PM To: Rotary motors in aircraft Subject: [FlyRotary] EC2 20B Injector Power Circuits I have been testing my wiring harness from the EC2. I found a = behavior that I did not expect. The manual drawing (EC2 manual) show a = single injector supply that splits at the Injector primary and secondary = disable switches. On my installation, I have 2 separate feeder = circuits, supply Primary comes from battery 1, and supply Secondary = comes from battery 2. I did this for redundancy. If I had a failure = such as a short to ground in either circuit, its related overload should = trip, but the other circuit should remain active. =20 While testing the injector circuits, I noticed what I would term an = abnormality. With both injector disable switches in the enable = position, I turned on the power for the primary circuit (I have LED = indicators on all circuits that annunciate power present) and the = secondary circuit also showed power present even though the power switch = for the secondary circuit was off. The same is true when the secondary = circuit is engaged and the primary is off. =20 Initially this led me to think I had miss wired something in the = circuit. After checking out the wiring, I found no issues. So I took a = closer look at the wiring diagram in the manual. It turns out the power = was being back feed through the injectors to the opposite circuit. On = the 20B version of the EC2, the injector control lines for each rotors = injectors are junctioned going into the EC2. For example the Rotor 1 = Primary and Secondary control lines are junctioned into a single input = point at the EC2. =20 I can see several situations where this may lead to undesirable = operation. For example, if the Primary circuit had a hard short to = ground, it would take out the primary circuit's overload (CB or Fuse.) = Since the primary and secondary circuits are electrically connected on = the control line, the other circuit would also trip. Another situation = that could occur is a medium to high resistance short. Current would = then flow uncontrolled through the unaffected circuit's injector to the = affected circuit's injector then to the resistance short. This could = keep both injectors on 100%. While this situation is unlikely, it seems = possible. I believe the 13B version uses separate control lines for each = injector, so this in not likely to be an issue on the 13B version. It appears that isolation diodes are needed to prevent these possible = problems. Before making any changes I have to look the circuit over = more closely, as well as a call to Tracy on the next service day. My = question to the group, especially anyone with a 20B, is am I looking at = this wrong? Thanks, Joe ------=_NextPart_000_002C_01C80EB7.6A781DC0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Al,
Thanks for the feedback.  Are = there any other=20 undocumented issues with the 20B controller that I should know = about? =20 How did the painting touch up work out?
Thanks,
Joe
----- Original Message -----
From:=20 Al = Gietzen=20
Sent: Sunday, October 14, 2007 = 9:41=20 PM
Subject: [FlyRotary] Re: EC2 = 20B Injector=20 Power Circuits

Joe;

 

You are=20 right.  We discovered this crossfeed issue some time back. =  Is=20 applies only to the 20B version as the 13B has separate drivers for = each set.=20  Install Schottky diodes in the circuits for each injector.  = Tracy is aware = of this,=20 and has installed the diodes in his as well.

 

Al

 

-----Original=20 Message-----
From: = Rotary=20 motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Joe = Ewen
Sent: Sunday, October 14, 2007 = 3:20=20 PM
To: Rotary = motors in=20 aircraft
Subject: = [FlyRotary]=20 EC2 20B Injector Power Circuits

 

I have been testing my = wiring=20 harness from the EC2.  I found a behavior that I did not = expect. =20 The manual drawing (EC2 manual) show a single injector supply that = splits at=20 the Injector primary and secondary disable switches.  On my = installation,=20 I have 2 separate feeder circuits, supply Primary comes from battery = 1,=20 and supply Secondary comes from battery 2.  I did this for=20 redundancy.  If I had a failure such as a short to ground in = either=20 circuit, its related overload should trip, but the other circuit = should remain=20 active. 

 

While testing the = injector=20 circuits, I noticed what I would term an abnormality.  With both = injector=20 disable switches in the enable position, I turned on the power for the = primary=20 circuit (I have LED indicators on all circuits that annunciate power = present)=20 and the secondary circuit also showed power present even though the = power=20 switch for the secondary circuit was off.  The same is true when = the=20 secondary circuit is engaged and the primary is off. =20

 

Initially this led me to = think I=20 had miss wired something in the circuit.  After checking out the = wiring,=20 I found no issues.  So I took a closer look at the wiring diagram = in the=20 manual.  It turns out the power was being back feed through the = injectors=20 to the opposite circuit.  On the 20B version of the EC2, the = injector=20 control lines for each rotors injectors are junctioned going into the=20 EC2.  For example the Rotor 1 Primary and Secondary control lines = are=20 junctioned into a single input point at the EC2. =20

 

I can see several = situations where=20 this may lead to undesirable operation.  For example, if the = Primary=20 circuit had a hard short to ground, it would take out the primary = circuit's=20 overload (CB or Fuse.)  Since the primary and secondary circuits = are=20 electrically connected on the control line, the other circuit would = also=20 trip.  Another situation that could occur is a medium to high = resistance=20 short.  Current would then flow uncontrolled through the = unaffected=20 circuit's injector to the affected circuit's injector then to the = resistance=20 short.  This could keep both injectors on 100%.  While this=20 situation is unlikely, it seems possible.

 

I believe the 13B = version=20 uses separate control lines for each injector, so this in not likely = to be an=20 issue on the 13B version.

 

It appears that = isolation diodes=20 are needed to prevent these possible problems.  Before making any = changes=20 I have to look the circuit over more closely, as well as a call to = Tracy on=20 the next service day.  My question to the group, especially = anyone with a=20 20B, is am I looking at this wrong?

 

Thanks,

Joe

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