X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 11 Jan 2006 10:20:43 -0500 Message-ID: X-Original-Return-Path: Received: from mta-out-1.udlp.com ([207.109.1.8] verified) by logan.com (CommuniGate Pro SMTP 5.0.6) with ESMTP id 921744 for lml@lancaironline.net; Wed, 11 Jan 2006 00:33:15 -0500 Received-SPF: none receiver=logan.com; client-ip=207.109.1.8; envelope-from=Christopher.Zavatson@baesystems.com Received: from mnexch01.MSGDOMAIN.MPLS.UDLP.COM ([10.1.62.20]) by mta-out-1.udlp.com (8.12.10/8.12.10) with ESMTP id k0B5Cpbk011033 for ; Tue, 10 Jan 2006 23:13:06 -0600 Received: from asdmngwia.udlp.com ([10.1.62.22] RDNS failed) by mnexch01.MSGDOMAIN.MPLS.UDLP.COM with Microsoft SMTPSVC(6.0.3790.211); Tue, 10 Jan 2006 23:27:32 -0600 Received: from DM-MN-06-MTA by asdmngwia.udlp.com with Novell_GroupWise; Tue, 10 Jan 2006 23:31:55 -0600 X-Original-Message-Id: X-Mailer: Novell GroupWise Internet Agent 6.5.4 X-Original-Date: Tue, 10 Jan 2006 23:31:41 -0600 From: "Christopher Zavatson" X-Original-To: Subject: Re: [LML] low fuel pressure indication Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-OriginalArrivalTime: 11 Jan 2006 05:27:32.0637 (UTC) FILETIME=[B8ED2CD0:01C6166F] Gerard, <<...the fuel pressure normally sits at 2 psi, just above redline in the = cruise, but intermittently (and apparently spontaneously) wanders to 5psi = before returning to 2 psi.>> I have noticed the same thing. A former Piper rep. told me that Piper = tried to figure out what causes this behavior many years ago. Despite all = the instrumentation they installed, they never could find the cause. They = left the matter as an unexplained but harmless quirk. The true redline for the engine is 0.5 psi. It is quite normal for = pressures to indicate lower while at high fuel flow rates, such as during = take-off, and highest at low/no flow. I don't recall seeing anything = lower than 2 psi in my plane. Less than 2psi would bother me if this was = a change from typical observation. Questions: Was this the first time = the pressure has dropped below 2 psi? Have you checked all of your = filters and strainers recently? Have you checked the flow rate of the = electric pump at the inlet to the carb. You might also want to check the = calibration of the gauge. I have seen aircraft gauges out of calibration = right out of the box and others that drifted over time. Other items that = may be relevant: Are your two pumps in series or parallel? Do you have a = fuel flow transducer in the line? Chris Zavatson N91CZ 360 std www.N91CZ.com