Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Tue, 03 Feb 2004 21:45:47 -0500 Message-ID: X-Original-Return-Path: Received: from imo-r03.mx.aol.com ([152.163.225.99] verified) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2974113 for lml@lancaironline.net; Tue, 03 Feb 2004 21:07:13 -0500 Received: from Sky2high@aol.com by imo-r03.mx.aol.com (mail_out_v36_r4.12.) id q.d4.4586124 (18555) for ; Tue, 3 Feb 2004 21:07:06 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Tue, 3 Feb 2004 21:07:05 EST Subject: Vacuum Pump Failure - a footnote X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1075860425" X-Mailer: 9.0 for Windows sub 460 -------------------------------1075860425 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit As I said in an earlier post, my vacuum pump failed about 1 hour from my home destination after delivering about 2 years and 150 hours of service. This pump had a blast air shroud around it, but was present thru a prop strike about 120 hours before its' demise. The shaft sheared in the proper shaft shear location. However, there was no damage to the pump chamber. This was a good thing since no particles were drawn back into the gyros. I do not know why the shaft sheared in cruise flight. In testing the new pump I did notice that is was delivering 5" during idle engine operation. The failed pump had fallen to 2-3 inches during idle for at least the last 40-50 hours. The next time a vacuum pump fails to hold the proper vacuum at 900-1000 rpm, it will be cause for me to investigate further. That is if I don't switch to an all electric system before that happens. Scott Krueger AKA Grayhawk Sky2high@aol.com II-P N92EX IO320 Aurora, IL (KARR) "...as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns - the ones we don't know we don't know." D. Rumsfeld -------------------------------1075860425 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
As I said in an earlier post, my vacuum pump failed about 1 hour from m= y=20 home destination after delivering about 2 years and 150 hours of service.&nb= sp;=20 This pump had a blast air shroud around it, but was present thru a prop stri= ke=20 about 120 hours before its' demise.
 
The shaft sheared in the proper shaft shear location.  However, th= ere=20 was no damage to the pump chamber.  This was a good thing since no=20 particles were drawn back into the gyros.  I do not know why the shaft=20 sheared in cruise flight.
 
In testing the new pump I did notice that is was delivering 5" during i= dle=20 engine operation. The failed pump had fallen to 2-3 inches during idle=20= for=20 at least the last 40-50 hours. 
 
The next time a vacuum pump fails to hold the proper vacuum at 900-1000= =20 rpm, it will be cause for me to investigate further.  That is if I don'= t=20 switch to an all electric system before that happens.=20
 
Scott Krueger=20 AKA Grayhawk
Sky2high@aol.com
II-P N92EX IO320 Aurora, IL=20 (KARR)

"...as we know, there are known knowns; there are things we kn= ow=20 we know. We also know there are known unknowns; that is to say we know there= are=20 some things we do not know. But there are also unknown unknowns - the ones w= e=20 don't know we don't know." D. Rumsfeld
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