X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 31 Mar 2014 07:36:24 -0400 Message-ID: X-Original-Return-Path: Received: from moutng.kundenserver.de ([212.227.17.13] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTPS id 6806928 for lml@lancaironline.net; Mon, 31 Mar 2014 04:26:49 -0400 Received-SPF: none receiver=logan.com; client-ip=212.227.17.13; envelope-from=nick@beaglepup.info Received: from Asus8 (prod02.i.lon.fullmeshnetworks.com [193.104.113.27]) by mrelayeu.kundenserver.de (node=mreue105) with ESMTP (Nemesis) id 0MT86g-1Wf18s49gs-00SAhx; Mon, 31 Mar 2014 10:26:13 +0200 X-Original-Message-ID: <0D7CCFCC728941449912889A0D9CDA03@Asus8> Reply-To: "Nick Long" From: "Nick Long" X-Original-To: "Lancair MailingList" References: In-Reply-To: Subject: Re: VMS1000 pressure gauges on LNC2 X-Original-Date: Mon, 31 Mar 2014 09:21:01 +0100 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0077_01CF4CC2.88710B70" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 16.4.3522.110 X-MimeOLE: Produced By Microsoft MimeOLE V16.4.3522.110 X-Antivirus: avast! (VPS 140331-0, 31/03/2014), Outbound message X-Antivirus-Status: Clean X-Provags-ID: V02:K0:ctnly4JM9i6AADIxq7zQQ5f27uu6lIRZ2vRLI2XU57V ST5BVX9kOLguPW/fjiRdU0QbV53bttY/kdErJ9vsWMNi5DIqas PoAqOj0+BIJaPn9+pALKBKcf+Xv/sJbg3ARrwMyV1csWUVNkIO ohRE5FQkKGmrgGksMRgsaEYyzQgBGygF9YHO5RhoLGKQwpMLg1 uIGDTDD2OcZrulK2jIDiTFB3M+1huXj7DrZs1rndgOBhUCCgOj jjzIphIYdFaEA5eD8qP6TA1LwE/siQ5tynFN8sk0+1fwJj09pf MBrWyBukzOkLK6SJg+ceeXn+mES5OVep4nQnNv5cAjAxXeuasz s/XKJeJppOQDAXa7coLc= This is a multi-part message in MIME format. ------=_NextPart_000_0077_01CF4CC2.88710B70 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Many thanks to everyone who has responded. I have a better idea now of = how the system functions and a list of things to check when I=E2=80=99m = next in the hangar. It seems there a few things that could be wrong: Air in the lines Sensor heads not working Bellows stuck Wiring issues On the latter point: These are analogue transducers sending a voltage to = the main unit, and the conversion to digital is done in the main unit. = If the voltage range is 0-50 mV full scale, then it is asking for a = resolution of 0.5 mV to get 1% FSD accuracy. From the electronics point = of view, that is a pretty tall order without special wiring techniques = and cables and connectors. One thing I think I will do is to rig up a dummy sensor unit, with a = knob that controls the output from 0-50 mV. That would be useful for = testing the wiring and the main unit, and a simple test for a faulty = sensor. Yours, Nick From: Timothy Farrell=20 Sent: Sunday, March 30, 2014 8:32 PM To: Nick Long=20 Subject: Re: VMS1000 pressure gauges on LNC2 Nick did you purge the lines? We have seen many times on new engines = that the pressures don't come on reliably until the lines have been = purged well of air. I know, the sensors should still be seeing pressure, = but it just doesn't seem to work until you actually get rid of the air = in the lines. That might help fix the oil. Were the wires to the gold = anodized box disconnected during your re-build? Having the wrong wires = in the wrong holes, or reversed, can cause some funky readings on the VM = systems.=20 Tim Aircrafters Sent from my iPhone On Mar 28, 2014, at 2:02 PM, "Nick Long" wrote: Hello All, I=E2=80=99ve got a Lancair 320 and we=E2=80=99ve just re-installed the = engine and are in the process of the annual inspection. Both the fuel and the oil pressure readings on the VMS1000 display are = very strange. The fuel pressure gives a reading when there is no = pressure and the oil pressure reads very low. A quick check with some = old steam gauges suggests the actual pressures are about right. The = pressure sensors are both in the engine bay, fed with flexible hoses. Is this likely to be the pressure sensors? Do they tend to misbehave? = Is there an easy way to check them? Or could it be in the wiring or the = display unit itself. I can=E2=80=99t see anything in the VMS1000 manual = about calibration. Any help gratefully received. Thanks, Nick ------=_NextPart_000_0077_01CF4CC2.88710B70 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
Many thanks to everyone who has responded. I have a better idea now = of how=20 the system functions and a list of things to check when I=E2=80=99m next = in the=20 hangar.
 
It seems there a few things that could be wrong:
Air in the lines
Sensor heads not working
Bellows stuck
Wiring issues
 
On the latter point: These are analogue transducers sending a = voltage to=20 the main unit, and the conversion to digital is done in the main unit. = If the=20 voltage range is 0-50 mV full scale, then it is asking for a resolution = of 0.5=20 mV to get 1% FSD accuracy. From the electronics point of view, that is a = pretty=20 tall order without special wiring techniques and cables and = connectors.
 
One thing I think I will do is to rig up a dummy sensor unit, with = a knob=20 that controls the output from 0-50 mV. That would be useful for testing = the=20 wiring and the main unit, and a simple test for a faulty sensor.
 
Yours,
 
Nick
 
 
 
Sent: Sunday, March 30, 2014 8:32 PM
Subject: Re: VMS1000 pressure gauges on = LNC2
 
Nick did you purge the lines?  We have seen many times on new = engines=20 that the pressures don't come on reliably until the lines have been = purged well=20 of air. I know, the sensors should still be seeing pressure, but it just = doesn't=20 seem to work until you actually get rid of the air in the lines. That = might help=20 fix the oil. Were the wires to the gold anodized box disconnected during = your=20 re-build? Having the wrong wires in the wrong holes, or reversed, can = cause some=20 funky readings on the VM systems.
 
Tim
Aircrafters
 
 
Sent from my iPhone

On Mar 28, 2014, at 2:02 PM, "Nick Long" <nick@beaglepup.info>=20 wrote:

Hello All,
 
I=E2=80=99ve got a Lancair 320 and we=E2=80=99ve just = re-installed the engine and are in=20 the process of the annual inspection.
 
Both the fuel and the oil pressure readings on the VMS1000 = display are=20 very strange. The fuel pressure gives a reading when there is no = pressure and=20 the oil pressure reads very low. A quick check with some old steam = gauges=20 suggests the actual pressures are about right. The pressure sensors = are both=20 in the engine bay, fed with flexible hoses.
 
Is this likely to be the pressure sensors? Do they tend to = misbehave? Is=20 there an easy way to check them? Or could it be in the wiring or the = display=20 unit itself. I can=E2=80=99t see anything in the VMS1000 manual about=20 calibration.
 
Any help gratefully received.
 
Thanks,
 
Nick
=
 
<= /DIV> ------=_NextPart_000_0077_01CF4CC2.88710B70--