X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-m26.mx.aol.com ([64.12.137.7] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2391511 for flyrotary@lancaironline.net; Wed, 17 Oct 2007 09:09:43 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.7; envelope-from=BMears9413@aol.com Received: from BMears9413@aol.com by imo-m26.mx.aol.com (mail_out_v38_r9.3.) id q.c20.22024267 (37033) for ; Wed, 17 Oct 2007 09:09:01 -0400 (EDT) Received: from webmail-mf02 (webmail-mf02.webmail.aol.com [64.12.88.215]) by cia-db02.mx.aol.com (v119.11) with ESMTP id MAILCIADB023-90a94716096d29c; Wed, 17 Oct 2007 09:09:01 -0400 References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: EC2 20B Injector Power Circuits Date: Wed, 17 Oct 2007 09:09:01 -0400 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: bmears9413@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8C9DED6055CC14D_8FC_FA3A_webmail-mf02.sysops.aol.com" X-Mailer: AOL WebMail 31361-STANDARD Received: from 65.182.71.8 by webmail-mf02.sysops.aol.com (64.12.88.215) with HTTP (WebMailUI); Wed, 17 Oct 2007 09:09:01 -0400 Message-Id: <8C9DED6055CC14D-8FC-7B38@webmail-mf02.sysops.aol.com> X-AOL-IP: 64.12.88.215 X-Spam-Flag: NO ----------MB_8C9DED6055CC14D_8FC_FA3A_webmail-mf02.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" So does this mean I shouldnt finish installing my EC2 cause I may have to se= nd it back to Tracy? Nows the time for me. I'm installing now. Bob Mears Supermarine Spitfire -----Original Message----- From: Joe Ewen To: Rotary motors in aircraft Sent: Sun, 14 Oct 2007 10:28 pm Subject: [FlyRotary] Re: EC2 20B Injector Power Circuits Hi Bob, Don't know if you don't ask.=C2=A0 A diode is a device that allows current t= o flow only in one direction (DC circuit.)=C2=A0 Schottky is a particular di= ode construction.=C2=A0 One desirable feature of a Schottky is that it has a= low forward voltage drop.=C2=A0 All diodes have a drop in voltage (like a s= mall resistor.)=C2=A0 In this case, the lower voltage drop allows the inject= ors to continue firing slightly longer than other diode types in the event o= f an alternator failure and lowering battery voltage. =C2=A0 On the 20B, the injector control lines are wired together, installing the di= odes prevents the current / voltage from back feeding between the primary an= d secondary circuits and the possible failure modes I noted earlier.=C2=A0 A= pplication of diode(s) in this manner is typically referred to as isolation=20= diodes. =C2=A0 Since the EC2 controller internal jumps the 2 controller power feeds, I inst= alled isolation diodes (Schottky) to prevent similar problems between the 2=20= supply circuits. =C2=A0 You may also find diodes useful in making=C2=A0annunciator press to test cir= cuits.=C2=A0 If you have 2 devices=C2=A0such as a transponder and a GPS that= both need to share altitude encoder inputs, isolation diodes would be used.= =C2=A0 Of course with any avionics installations, follow the manufactures gu= idelines. =C2=A0 Joe ----- Original Message -----=20 From: bob.kaufmann=20 To: Rotary motors in aircraft=20 Sent: Sunday, October 14, 2007 10:16 PM Subject: [FlyRotary] Re: EC2 20B Injector Power Circuits Al=20 =C2=A0 Hate to continue to display my ignorance but what is a Schottky diodes.=C2= =A0 When it comes to electronics I=E2=80=99m as dumb as a stump. =C2=A0 Bob K =C2=A0 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beha= lf Of Al Gietzen Sent: Sunday, October 14, 2007 5:42 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: EC2 20B Injector Power Circuits =C2=A0 Joe; =C2=A0 You are right.=C2=A0 We discovered this crossfeed issue some time back. =C2= =A0Is applies only to the 20B version as the 13B has separate drivers for ea= ch set. =C2=A0Install Schottky diodes in the circuits for each injector.=C2= =A0 Tracy is aware of this, and has installed the diodes in his as well. =C2=A0 Al =C2=A0 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beha= lf Of Joe Ewen Sent: Sunday, October 14, 2007 3:20 PM To: Rotary motors in aircraft Subject: [FlyRotary] EC2 20B Injector Power Circuits =C2=A0 I have been testing my wiring harness from the EC2.=C2=A0 I found a behavior= that I did not expect.=C2=A0 The manual drawing (EC2 manual) show a single=20= injector supply that splits at the Injector primary and secondary disable sw= itches.=C2=A0 On my installation, I have 2 separate feeder circuits, supply=20= Primary comes from battery 1, and=C2=A0supply Secondary comes from battery 2= .=C2=A0 I did this for redundancy.=C2=A0 If I had a failure such as a short=20= to ground in either circuit, its related overload should trip, but the other= circuit should remain active.=C2=A0=20 =C2=A0 While testing the injector circuits, I noticed what I would term an abnormal= ity.=C2=A0 With both injector disable switches in the enable position, I tur= ned on the power for the primary circuit (I have LED indicators on all circu= its that annunciate power present) and the secondary circuit also showed pow= er present even though the power switch for the secondary circuit was off.= =C2=A0 The same is true when the secondary circuit is engaged and the primar= y is off.=C2=A0=20 =C2=A0 Initially this led me to think I had miss wired something in the circuit.= =C2=A0 After checking out the wiring, I found no issues.=C2=A0 So I took a c= loser look at the wiring diagram in the manual.=C2=A0 It turns out the power= was being back feed through the injectors to the opposite circuit.=C2=A0 On= the 20B version of the EC2, the injector control lines for each rotors inje= ctors are junctioned going into the EC2.=C2=A0 For example the Rotor 1 Prima= ry and Secondary control lines are junctioned into a single input point at t= he EC2.=C2=A0=20 =C2=A0 I can see several situations where this may lead to undesirable operation.= =C2=A0 For example, if the Primary circuit had a hard short to ground, it wo= uld take out the primary circuit's overload (CB or Fuse.)=C2=A0 Since the pr= imary and secondary circuits are electrically connected on the control line,= the other circuit would also trip.=C2=A0 Another situation that could occur= is a medium to high resistance short.=C2=A0 Current would then flow uncontr= olled through the unaffected circuit's injector to the affected circuit's in= jector then to the resistance short.=C2=A0 This could keep both injectors on= 100%.=C2=A0 While this situation is unlikely, it=C2=A0seems possible. =C2=A0 I believe=C2=A0the 13B version uses separate control lines for each injector= , so this in not likely to be an issue on the 13B version. =C2=A0 It appears that isolation diodes are needed to prevent these possible proble= ms.=C2=A0 Before making any changes I have to look the circuit over more clo= sely, as well as a call to Tracy on the next service day.=C2=A0 My question=20= to the group, especially anyone with a 20B, is am I looking at this wrong? =C2=A0 Thanks, Joe ________________________________________________________________________ Email and AIM finally together. You've gotta check out free AOL Mail! - http= ://mail.aol.com ----------MB_8C9DED6055CC14D_8FC_FA3A_webmail-mf02.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8" So does this mean I shouldnt finish installing my EC2 cause I may have to se= nd it back to Tracy? Nows the time for me. I'm installing now.

Bob Mears
Supermarine Spitfire


-----Original Message-----
From: Joe Ewen <Jewen@comporium.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sun, 14 Oct 2007 10:28 pm
Subject: [FlyRotary] Re: EC2 20B Injector Power Circuits

Hi Bob,
Don't know if you don't ask.  A diode=20= is a device that allows current to flow only in one direction (DC circuit.)&= nbsp; Schottky is a particular diode construction.  One desirable featu= re of a Schottky is that it has a low forward voltage drop.  All diodes= have a drop in voltage (like a small resistor.)  In this case, the low= er voltage drop allows the injectors to continue firing slightly longer than= other diode types in the event of an alternator failure and lowering batter= y voltage.
 
On the 20B, the injector control lines are=20= wired together, installing the diodes prevents the current / voltage from ba= ck feeding between the primary and secondary circuits and the possible failu= re modes I noted earlier.  Application of diode(s) in this manner is ty= pically referred to as isolation diodes.
 
Since the EC2 controller internal jumps the= 2 controller power feeds, I installed isolation diodes (Schottky) to preven= t similar problems between the 2 supply circuits.
 
You may also find diodes useful in making&n= bsp;annunciator press to test circuits.  If you have 2 devices suc= h as a transponder and a GPS that both need to share altitude encoder inputs= , isolation diodes would be used.  Of course with any avionics installa= tions, follow the manufactures guidelines.
 
Joe
----- Original Message -----
F= rom: bob.kaufmann
Sent: Sunday, October 14, 2007 10:16=20= PM
Subject: [FlyRotary] Re: EC2 20B Inje= ctor Power Circuits

Al
 
Hate to continue to display my ignorance but= what is a Schottky diodes.  When it comes to electronics I=E2=80=99m a= s dumb as a stump.
 
Bob K
 
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beha= lf Of Al Gietzen
Sent: Sunday, October 14, 2007 5:42 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: EC2 20B Injector Power Circuits
 
Joe;
 
You are right.  We discovered this crossfe= ed 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 cir= cuits 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=20= 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 har= ness 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 th= e 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=20= related overload should trip, but the other circuit should remain active.&nb= sp;
 
While testing the injector circui= ts, I noticed what I would term an abnormality.  With both injector dis= able 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= ) 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 se= condary circuit is engaged and the primary is off. 
 
Initially this led me to think I=20= 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=20= the manual.  It turns out the power was being back feed through the inj= ectors to the opposite circuit.  On the 20B version of the EC2, the inj= ector control lines for each rotors injectors are junctioned going into the=20= EC2.  For example the Rotor 1 Primary and Secondary control lines are j= unctioned into a single input point at the EC2. 
 
I can see several situations wher= e 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 el= ectrically connected on the control line, the other circuit would also trip.=   Another situation that could occur is a medium to high resistance sho= rt.  Current would then flow uncontrolled through the unaffected circui= t's injector to the affected circuit's injector then to the resistance short= .  This could keep both injectors on 100%.  While this situation i= s unlikely, it seems possible.
 
I believe the 13B version us= es 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 chang= es I have to look the circuit over more closely, as well as a call to Tracy=20= on the next service day.  My question to the group, especially anyone w= ith a 20B, is am I looking at this wrong?
 
Thanks,
Joe
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