X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 27 Jul 2012 08:17:59 -0400 Message-ID: X-Original-Return-Path: Received: from mail-pb0-f52.google.com ([209.85.160.52] verified) by logan.com (CommuniGate Pro SMTP 6.0c1) with ESMTPS id 5680244 for lml@lancaironline.net; Fri, 27 Jul 2012 00:54:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.160.52; envelope-from=pjdmiller@gmail.com Received: by pbbro8 with SMTP id ro8so4372775pbb.25 for ; Thu, 26 Jul 2012 21:53:55 -0700 (PDT) Received: by 10.68.239.103 with SMTP id vr7mr11218746pbc.0.1343364835786; Thu, 26 Jul 2012 21:53:55 -0700 (PDT) X-Original-Return-Path: Received: from [192.168.15.2] (S01060017ee00b6c0.cg.shawcable.net. [174.0.115.173]) by mx.google.com with ESMTPS id ov8sm1120274pbb.2.2012.07.26.21.53.54 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 26 Jul 2012 21:53:55 -0700 (PDT) From: Paul Miller Content-Type: multipart/alternative; boundary="Apple-Mail=_11BD52D2-CAA3-4CF1-A7D3-AC494B1DEB01" X-Original-Message-Id: <0869969B-A9B5-4EB8-BF52-C046D2FC6B75@gmail.com> Mime-Version: 1.0 (Mac OS X Mail 6.0 \(1485\)) Subject: Re: [LML] IO-360 / VM1000 CHT issues X-Original-Date: Thu, 26 Jul 2012 22:53:40 -0600 References: X-Original-To: "Lancair Mailing List" In-Reply-To: X-Mailer: Apple Mail (2.1485) --Apple-Mail=_11BD52D2-CAA3-4CF1-A7D3-AC494B1DEB01 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=iso-8859-1 This is a good article if you want to test a probe. http://www.rst-engr.com/rst/articles/egtcht.pdf Paul Calgary On 2012-07-26, at 9:19 PM, Louis Gabriel wrote: > Hello all! >=20 > I have a bizarre CHT issue that I'm currently troubleshooting, and I = could use some advice and perhaps a source for a part. >=20 > I have a LNC2 with an IO-360-C1C (angle valve 200 hp). The engine has = 365 hours SMOH (which was about 10 years ago), a history of good = compressions, and clean oil analysis results. It is burning about half = a quart an hour, but I suspect most of that is through the No. 1 = cylinder. I'm currently running mineral oil for 25 hours in an attempt = to reseat the oil ring in that cylinder. That issue is most likely = unrelated, but I figured I'd mention it in case I am overlooking = something. I have experienced slightly higher oil temps because of the = oil choice, but otherwise no issues. >=20 > All four EGTs and CHTs are monitored by a Vision Microsystems VM1000. = I fly from a 5000' MSL field, and on a normal summer day on a 140 mph = climb, I usually see CHTs between 350 and 380. >=20 > Two flights ago, I took off on a standard climb profile and the No. 2 = CHT ran away. Climbing through pattern altitude it was already pushing = 400, and after slowing my climb rate, accelerating to 160, and adding = fuel, it reached a peak around 420. All the other cylinders were around = 350 initially and cooled down to 300-330 while the No. 2 stayed hot. = Even downhill on the way back to the airport with the power around 15", = the No. 2 stayed high (around 400) while the other three cylinders were = in the high 200s / low 300s. The highest oil temp I saw was 212. >=20 > Upon inspection, there were no obstructions to the airflow, and = everything in the cowling looked unchanged--leading me to suspect = instrumentation. >=20 > I was unable to duplicate the problem on the ground; I ran for 15 = minutes, got all four cylinders up above 400, and they stayed mostly = matched. >=20 > After cleaning and reseating the connections to the No. 2 CHT probe = and double checking the baffling, I went for a test flight...and the = problem came back. Once again, the No. 2 went up to around 420 and the = others stayed in the mid 300s. The No. 2 stayed hot even after pulling = the power. However, after some delay getting into the pattern, they all = came down to around 300 before landing and were fairly well matched on = the taxi in. >=20 > At this point, I'm still suspecting a faulty CHT indication, as the = engine runs quite smoothly and the cylinder is getting plenty of air. >=20 > I was wondering if anyone knows the failure mode of VM1000 CHT = probes--does this sound like it's on the fritz? Also...does anyone know = where I can get a new CHT probe for the system? Am I on the right track = with troubleshooting? >=20 > My next step is to swap the probes from the No. 2 and No. 4 cylinders = and see if the problem moves. >=20 > Thanks for your time everyone -=20 >=20 > Louis Gabriel > LNC2, KRTS >=20 >=20 >=20 >=20 --Apple-Mail=_11BD52D2-CAA3-4CF1-A7D3-AC494B1DEB01 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=iso-8859-1 This = is a good article if you want to test a probe.


Paul
Calgary
On 2012-07-26, at 9:19 PM, Louis Gabriel = <louis@gabriels.us> = wrote:

Hello all!

I have a bizarre = CHT issue that I'm currently troubleshooting, and I could use some = advice and perhaps a source for a part.

I have = a LNC2 with an IO-360-C1C (angle valve 200 hp).  The engine has 365 = hours SMOH (which was about 10 years ago), a history of good = compressions, and clean oil analysis results.  It is burning about = half a quart an hour, but I suspect most of that is through the No. 1 = cylinder.  I'm currently running mineral oil for 25 hours in an = attempt to reseat the oil ring in that cylinder.  That issue is = most likely unrelated, but I figured I'd mention it in case I am = overlooking something.  I have experienced slightly higher oil = temps because of the oil choice, but otherwise no issues.

All four EGTs and CHTs are monitored by a Vision = Microsystems VM1000.  I fly from a 5000' MSL field, and on a normal = summer day on a 140 mph climb, I usually see CHTs between 350 and = 380.

Two flights ago, I took off on a standard climb profile = and the No. 2 CHT ran away.  Climbing through pattern altitude it = was already pushing 400, and after slowing my climb rate, accelerating = to 160, and adding fuel, it reached a peak around 420.  All the = other cylinders were around 350 initially and cooled down to 300-330 = while the No. 2 stayed hot.  Even downhill on the way back to the = airport with the power around 15", the No. 2 stayed high (around 400) = while the other three cylinders were in the high 200s / low 300s. =  The highest oil temp I saw was 212.

Upon inspection, there were no obstructions to the = airflow, and everything in the cowling looked unchanged--leading me to = suspect instrumentation.

I was unable to = duplicate the problem on the ground; I ran for 15 minutes, got all four = cylinders up above 400, and they stayed mostly matched.

After cleaning and reseating the connections to the = No. 2 CHT probe and double checking the baffling, I went for a test = flight...and the problem came back.  Once again, the No. 2 went up = to around 420 and the others stayed in the mid 300s.  The No. 2 = stayed hot even after pulling the power.  However, after some delay = getting into the pattern, they all came down to around 300 before = landing and were fairly well matched on the taxi in.

At this point, I'm still suspecting a faulty CHT = indication, as the engine runs quite smoothly and the cylinder is = getting plenty of air.

I was wondering if = anyone knows the failure mode of VM1000 CHT probes--does this sound like = it's on the fritz?  Also...does anyone know where I can get a new = CHT probe for the system?  Am I on the right track with = troubleshooting?

My next step is to swap the probes from the No. 2 = and No. 4 cylinders and see if the problem = moves.

Thanks for your time everyone = - 

Louis Gabriel
LNC2, = KRTS





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