X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 22 Mar 2009 16:13:59 -0400 Message-ID: X-Original-Return-Path: Received: from nskntmtas04p.mx.bigpond.com ([61.9.168.146] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3555186 for lml@lancaironline.net; Sat, 21 Mar 2009 22:24:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=61.9.168.146; envelope-from=frederickmoreno@bigpond.com Received: from nskntotgx02p.mx.bigpond.com ([121.221.148.35]) by nskntmtas04p.mx.bigpond.com with ESMTP id <20090322022335.RYCY1877.nskntmtas04p.mx.bigpond.com@nskntotgx02p.mx.bigpond.com> for ; Sun, 22 Mar 2009 02:23:35 +0000 Received: from Razzle ([121.221.148.35]) by nskntotgx02p.mx.bigpond.com with ESMTP id <20090322022334.PDWL6515.nskntotgx02p.mx.bigpond.com@Razzle> for ; Sun, 22 Mar 2009 02:23:34 +0000 From: "Frederick Moreno" X-Original-To: "Lancair Mail" Subject: Crankcase pressurization X-Original-Date: Sun, 22 Mar 2009 11:23:29 +0900 X-Original-Message-ID: <29364FA9D5104FCEBDEC166320135314@Razzle> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0073_01C9AAE0.A231D1E0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6838 Importance: Normal Thread-Index: AcmqlTBO5SQI+I7wQ9GxVCrNR85oBg== X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-RPD-ScanID: Class unknown; VirusThreatLevel unknown, RefID str=0001.0A150205.49C5A127.001C,ss=1,fgs=0 This is a multi-part message in MIME format. ------=_NextPart_000_0073_01C9AAE0.A231D1E0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I wrote earlier that my IO-550 was dumping oil out the air oil = separator, and with some fiddling with the plumbing, it appeared I solved the = problem. High power climbs yielded no oil loss. Ground tests showed no blow by. Problem solved. =20 =20 Wrong. =20 =20 New hypothesis: It appears that the losses occur during cruise, not take = off and climb. I climb at 160 knots, cowl flaps open. I cruise at 200-220 IAS, cowl flaps closed. The ram pressure at cruise is 1.5-1.7 times = greater than in climb. =20 =20 So the current hypothesis is that the crankcase could be pressurized by external air pressure and the air flow through the crankcase carries oil overboard.=20 =20 A bit of research suggests checking the crankshaft nose seal and the oil filler cap. =20 =20 Has anyone had problems with Continental crank case pressurization? = What have you learned? =20 =20 My next step is to pull the breather tube off the air oil separator and = use some low pressure compressed air to pressurize the crankcase (engine = off) and see if I can find some leaks. The next level of complexity is to = put a tube up the crankcase breather, connect to an airspeed indicator in the cockpit to check pressure, and go flying and see what happens.=20 =20 Other suggestions or other experience that might help guide us through = this maze? =20 Thanks in advance,=20 =20 Fred Moreno ------=_NextPart_000_0073_01C9AAE0.A231D1E0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

I wrote earlier that my IO-550 was dumping oil out = the air oil separator, and with some fiddling with the plumbing, it appeared I = solved the problem.   High power climbs yielded no oil loss.  Ground tests showed no blow = by.  Problem solved. 

 

Wrong. 

 

New hypothesis: It appears that the losses occur = during cruise, not take off and climb.   I climb at 160 knots, cowl = flaps open.  I cruise at 200-220 IAS, cowl flaps closed.  The ram = pressure at cruise is 1.5-1.7 times greater than in climb.  =

 

So the current hypothesis is that the crankcase could = be pressurized by external air pressure and the air flow through the crankcase carries = oil overboard.

 

A bit of research suggests checking the crankshaft = nose seal and the oil filler cap. 

 

Has anyone had problems with Continental crank case = pressurization?  What have you learned? 

 

My next step is to pull the breather tube off the air = oil separator and use some low pressure compressed air to pressurize the = crankcase (engine off) and see if I can find some leaks.   The next = level of complexity is to put a tube up the crankcase breather, connect to an = airspeed indicator in the cockpit to check pressure, and go flying and see what = happens.

 

Other suggestions or other experience that might help = guide us through this maze?

 

Thanks in advance,

 

Fred Moreno

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