X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 23 Aug 2005 10:48:30 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m27.mx.aol.com ([64.12.137.8] verified) by logan.com (CommuniGate Pro SMTP 5.0c1) with ESMTP id 678918 for lml@lancaironline.net; Tue, 23 Aug 2005 10:18:22 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.8; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m27.mx.aol.com (mail_out_v38_r4.1.) id q.f5.5811280f (4254) for ; Tue, 23 Aug 2005 10:17:32 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Tue, 23 Aug 2005 10:17:32 EDT Subject: Re: [LML] Hydraulic pump Schematic(s) X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1124806652" X-Mailer: 9.0 Security Edition for Windows sub 5009 X-Spam-Flag: NO -------------------------------1124806652 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 8/23/2005 8:48:05 A.M. Central Standard Time, dfs155@adelphia.net writes: Scott, in the schematic submitted, can't for the life of me figure out why the breaker (fuse?) that goes to the gear switch would be connected to the main bus rather than the down-stream side of the 50 amp pump breaker. The way it's shown, one would need to pull TWO breakers to positively safe the system to do a proper emergency gear drop instead of just the one (you want to de-energize the relays, since they're only for intermittent use, as well as the main power to the pump circuit in case of a stuck relay, right?). In addition, there really needs to be a diode added to each relay control terminal to ground (cathode to the terminal) or the pressure switches and gear switch contacts will die an early death from the inductive kick when the current to the relay coil is interrupted, e.g., relay is turned off. FWIW, the same is true of the starter relay, which is identical to the pump relays, at least in my airplane. As a firm proponent of the KISS principal, especially for a system that is likely to be needed while in a relatively high stress situation, having to remember to pull just one breaker instead of two seems preferable. Dan, Note that Bob's "just pull the relay breaker" is fine for testing (assuming the system was wired the Lancair way). You are right that ultimately one should be able to pull the motor breaker, too. KISS would imply that the same method used for testing would be used in an emergency. Remember the construction manual warning about not pulling both breakers. Yes, you are right about the coil diodes (or MOVs, see Bob Nuckoll's Aeroelectric web site) and I have them installed. It just seemed like there wasn't room on the Lancair diagram for more stuff and I wanted to emphasize the other, more severe issues. KISS works for me....... Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) -------------------------------1124806652 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 8/23/2005 8:48:05 A.M. Central Standard Time,=20 dfs155@adelphia.net writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Scott,=20 in the schematic submitted, can't for the life of me figure out why
the= =20 breaker (fuse?) that goes to the gear switch would be connected to the
= main=20 bus rather than the down-stream side of the 50 amp pump breaker. The
wa= y=20 it's shown, one would need to pull TWO breakers to positively safe=20 the
system to do a proper emergency gear drop instead of just the one (= you=20 want
to de-energize the relays, since they're only for intermittent use= , as=20 well
as the main power to the pump circuit in case of a stuck relay,=20 right?).

In addition, there really needs to be a diode added to eac= h=20 relay control
terminal to ground (cathode to the terminal) or the press= ure=20 switches and
gear switch contacts will die an early death from the=20 inductive kick when
the current to the relay coil is interrupted, e.g.,= =20 relay is turned off.
FWIW, the same is true of the starter relay, which= is=20 identical to the pump
relays, at least in my airplane.

As a firm= =20 proponent of the KISS principal, especially for a system that is
likely= to=20 be needed while in a relatively high stress situation, having to
rememb= er=20 to pull just one breaker instead of two seems=20 preferable.
Dan,
 
Note that Bob's "just pull the relay breaker" is fine for testing (assu= ming=20 the system was wired the Lancair way).  You are right that ultimately o= ne=20 should be able to pull the motor breaker, too.  KISS would imply that t= he=20 same method used for testing would be used in an emergency.  Remember t= he=20 construction manual warning about not pulling both breakers.
 
Yes, you are right about the coil diodes (or MOVs, see Bob Nuckoll's=20 Aeroelectric web site) and I have them installed.  It just seemed like=20 there wasn't room on the Lancair diagram for more stuff and I wanted to=20 emphasize the other, more severe issues.
 
KISS works for me.......
 
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)



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