X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 10 Oct 2007 15:47:50 -0400 Message-ID: X-Original-Return-Path: Received: from [68.98.211.24] (HELO systems3.net) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2379703 for lml@lancaironline.net; Wed, 10 Oct 2007 13:43:59 -0400 Received-SPF: none receiver=logan.com; client-ip=68.98.211.24; envelope-from=cberland@systems3.net Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C80B65.0CAE02A1" X-MimeOLE: Produced By Microsoft Exchange V6.5 Subject: [LML] Legacy Engine/Prop/Speed/ Vibration? X-Original-Date: Wed, 10 Oct 2007 10:43:19 -0700 X-Original-Message-ID: <87C33F695961494D886EB3B6C8A47651400C95@s3server.Systems3.local> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [LML] Legacy Engine/Prop/Speed/ Vibration? Thread-Index: AcgLNvBVyhN6yUFVSf+bvOA5YjH1iQALP7yQ From: "Craig Berland" X-Original-To: "Lancair Mailing List" This is a multi-part message in MIME format. ------_=_NextPart_001_01C80B65.0CAE02A1 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Erik, =20 It may be easier to "delete" things. I don't think it is the engine. By just changing indicated airspeed you are changing engine parameters only very very slightly. You are changing prop blade angle. Possible source. And you are changing pressures on the various parts of the airplane. Gear doors, cowl, etc. Possible source. If it is indeed RPM sensitive, then the prop would be my first pick assuming you have ruled out FM. (f***g magic). I will be at Palomar tomorrow, hope to see you. Craig Berland =20 Hi All: Just wondering if anyone has an idea on which way to go to start trouble shooting this problem.=20 Here are the particulars: I have a Legacy with about 120 hrs on it. Performance Engines IO-550 / Hartzell Prop / Mags. It has been running exceptionally well, very smooth until just yesterday when I first noticed a sort of nondescript rumble/vibration after a long descent at relatively high speed, from 17,500'.=20 As we slowed to enter the pattern for landing it cleared up and everything seemed normal. I went out and flew today to see if it was just an anomaly......apparently it was NOT. * A download of all the engine parameters was normal...... nothing out of the ordinary. * Engine run-up and full power run were all normal/smooth. * Takeoff and initial climb out were all normal with no vibration UNTIL we accelerated through approximately 165kts. * At 165kts and greater, on three successive flights, we felt a distinct cyclical type vibration setting up. It's a bit hard to describe in words but it does NOT seem to be a steady vibration (like a gear door) but seems to feel almost like a prop out of balance. * Without touching the power or prop we can make the vibration go away by raising the nose and slowing < 165kts. * When we do get the vibration > 165kts..... you can mitigate it somewhat by increasing prop RPM. The vibration is still there but not has bad. * The prop is NOT surging in any way, RPM's are rock steady and remain where they are set. * The issue is serious enough, in my mind, that I am DRIVING tomorrow from San Diego to Las Vegas.......and I HATE driving;))) So in summary, it seems this vibration just happened somewhat spontaneously (ie. not progressively worsened over time) and although were not ruling anything out, it seems to be Engine/Prop/Speed related. We would GREATLY appreciate any ideas, comments, suggestions.... we are kind of at a loss as to which way to head in troubleshooting/fixing this problem. Best regards, Erik Larson asw20747@aol.com (619) 301-7475 ________________________________ Email and AIM finally together. You've gotta check out free AOL Mail ! ------_=_NextPart_001_01C80B65.0CAE02A1 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
Erik,
 
It may be easier to "delete" things.  I = don't=20 think it is the engine. By just changing indicated airspeed you=20 are changing engine parameters only very very slightly.  You = are=20 changing prop blade angle. Possible source.  And you are changing = pressures=20 on the various parts of the airplane.  Gear doors, cowl, etc.  = Possible source. If it is indeed RPM sensitive, then the prop would be = my first=20 pick assuming you have ruled out FM. (f***g magic).  I will be at = Palomar=20 tomorrow, hope to see you.
Craig Berland

 


Hi = All:

Just=20 wondering if anyone has an idea on which way to go to start trouble = shooting=20 this problem.

Here are the particulars:

I have a Legacy = with=20 about 120 hrs on it.  Performance Engines IO-550 / Hartzell Prop /=20 Mags.

It has been running exceptionally well, very smooth until = just=20 yesterday when I first noticed a sort of nondescript rumble/vibration = after a=20 long descent at relatively high speed, from 17,500'.

As we = slowed to=20 enter the pattern for landing it cleared up and everything seemed = normal. =20 I went out and flew today to see if it was just an = anomaly......apparently it=20 was NOT.

*  A download of all the engine parameters was = normal......=20 nothing out of the ordinary.
*  Engine run-up and full power run = were=20 all normal/smooth.
*  Takeoff and initial climb out were all = normal with=20 no vibration UNTIL we accelerated through approximately = 165kts.
*  At=20 165kts and greater, on three successive flights, we felt a distinct=20 cyclical type vibration setting up.  It's a bit hard to = describe in=20 words but it does NOT seem to be a=20 steady           &= nbsp; =20 vibration (like a gear door) but seems to feel almost like a prop out of = balance.
*  Without touching the power or prop we can make the = vibration=20 go away by raising the nose and slowing < 165kts.
*  When we = do get=20 the vibration > 165kts..... you can mitigate it somewhat by = increasing prop=20 RPM.  The vibration is still there but not has bad.
* The prop = is NOT=20 surging in any way, RPM's are rock steady and remain where they are=20 set.
*  The issue is serious enough, in my mind, that I am = DRIVING=20 tomorrow from San Diego to Las Vegas.......and I HATE = driving;)))

So in=20 summary, it seems this vibration just happened somewhat spontaneously = (ie. not=20 progressively worsened over time) and although were not ruling anything = out, it=20 seems to be Engine/Prop/Speed related.

We would GREATLY = appreciate any=20 ideas, comments, suggestions.... we are kind of at a loss as to which = way to=20 head in troubleshooting/fixing this problem.

Best = regards,

Erik=20 Larson

asw20747@aol.com
(619) = 301-7475
Email and AIM finally together. You've gotta check out free AOL Mail!
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