X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao107.cox.net ([68.230.241.39] verified) by logan.com (CommuniGate Pro SMTP 5.3.5) with ESMTP id 4222578 for flyrotary@lancaironline.net; Thu, 15 Apr 2010 11:33:42 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.39; envelope-from=alventures@cox.net Received: from fed1rmimpo01.cox.net ([70.169.32.71]) by fed1rmmtao107.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20100415153307.JHGS1969.fed1rmmtao107.cox.net@fed1rmimpo01.cox.net> for ; Thu, 15 Apr 2010 11:33:07 -0400 Received: from BigAl ([72.192.128.205]) by fed1rmimpo01.cox.net with bizsmtp id 5rZ61e0054S1t5C03rZ6Tv; Thu, 15 Apr 2010 11:33:06 -0400 X-VR-Score: -30.00 X-Authority-Analysis: v=1.1 cv=cnbFproiWJRJ9R5Ra84R6dpMd929KZAD6MF01mSBA8Y= c=1 sm=1 a=T-PcxMWY_KAA:10 a=Vegc0WxVmH5BHtpNDyThtA==:17 a=Ia-xEzejAAAA:8 a=nUuTZ29dAAAA:8 a=Pyxl3iawRHC_49qOtZAA:9 a=omRq2kcEvWIP8S8qOjEA:7 a=qx747wAdCPZwHHtlj2Z1Ego_4BkA:4 a=CjuIK1q_8ugA:10 a=EzXvWhQp4_cA:10 a=n7H2LDAWNYkWx05O:21 a=5XPqf6EJq09_R5dZ:21 a=yMhMjlubAAAA:8 a=ZOKmUgG7aIS5tPzG8lMA:9 a=q8XWo6B4ygYdZfbtGAUA:7 a=-ouV2RRcXIh1VASjV0n7HEvXKaEA:4 a=Vegc0WxVmH5BHtpNDyThtA==:117 X-CM-Score: 0.00 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Weird sound during descent Date: Thu, 15 Apr 2010 08:33:39 -0800 Message-ID: <69FD42861FCE4B56BA63FE4F5023CBA8@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000E_01CADC76.5966EE50" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6856 Importance: Normal Thread-Index: AcrcriGfD1cmEwzTSRyKoTV2i5+M8QACiANA In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_000E_01CADC76.5966EE50 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Jeff; =20 Hard to tell, but sounds like something vibrating at the particular frequencies set up under those conditions. There are times I also hear strange noises on descents, and very low throttle settings - sometimes there, sometimes not. You finally just accept them as normal. =20 Not likely anything to do with the thrust bearing. I have a pusher and you'd think the forces are reversed; although I guess if the engine is = being driven by the prop rather than vice-versa, the result is the same. If = there is some issue about steep descents, I'd like to know as well. =20 Al =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Jeff Whaley Sent: Thursday, April 15, 2010 7:13 AM To: Rotary motors in aircraft Subject: [FlyRotary] Weird sound during descent =20 I have been hearing a weird buzzing sound usually detectable on base leg = at low power settings. It is hard to describe in text but is repeatedly as zzuuzz, zzuuzz, zzuuzz . I thought it was wind noise escaping between the fuselage and gear legs, = as there are no fairings between the fuselage and top of the cub-style = gear. Last night it was bit bumpy and during one descent there was a good bump that lifted me against the seat belts -- the noise stopped. Tracy had cautioned me against low power steeps descents, something = about thrust bearing and/or snubber - maybe refresh me on that one Tracy? However, an approach speed of 500 fpm, 80 mph, 3000 rpm, mp <10", is not what I'd consider steep.=20 =20 Anyone care to give me a clue as to what I might be hearing? If I get a chance to fly this weekend, I'll experiment to see if I can stop/change the noise with speed or attitude adjustments.=20 Jeff __________ Information from ESET NOD32 Antivirus, version of virus = signature database 5031 (20100415) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com This message, and the documents attached hereto, is intended only for = the addressee and may contain privileged or confidential information. Any unauthorized disclosure is strictly prohibited. If you have received = this message in error, please notify us immediately so that we may correct = our internal records. Please then delete the original message. Thank you. ------=_NextPart_000_000E_01CADC76.5966EE50 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Jeff;

 

Hard to tell, but sounds like = something vibrating at the particular frequencies set up under those conditions. = There are times I also hear strange noises on descents, and very low throttle settings – sometimes there, sometimes not. You finally just accept = them as normal.

 

Not likely anything to do with = the thrust bearing.  I have a pusher and you’d think the forces = are reversed; although I guess if the engine is being driven by the prop = rather than vice-versa, the result is the same.  = If there is some issue about steep descents, I’d like to know as = well.

 

Al

 

-----Original = Message-----
From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Jeff Whaley
Sent: Thursday, April 15, = 2010 7:13 AM
To: Rotary motors in = aircraft
Subject: [FlyRotary] = Weird sound during descent

 

I have been hearing a weird buzzing sound = usually detectable on base leg at low power settings.  It is hard to = describe in text but is repeatedly as zzuuzz, zzuuzz, zzuuzz .

I thought it was wind noise escaping between = the fuselage and gear legs, as there are no fairings between the fuselage = and top of the cub-style gear.

Last night it was bit bumpy and during one = descent there was a good bump that lifted me against the seat belts -- the noise stopped.

Tracy had cautioned me against low power = steeps descents, something about thrust bearing and/or snubber – maybe = refresh me on that one Tracy?

However, an approach speed of 500 fpm, 80 = mph, 3000 rpm, mp <10”, is not what I’d consider steep. =

 

Anyone care to give me a clue as to what I = might be hearing?

If I get a chance to fly this weekend, = I’ll experiment to see if I can stop/change the noise with speed or attitude adjustments.

Jeff



__________ Information from ESET NOD32 Antivirus, version of virus = signature database 5031 (20100415) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

This message, and the documents attached = hereto, is intended only for the addressee and may contain privileged or = confidential information. Any unauthorized disclosure is strictly prohibited. If you = have received this message in error, please notify us immediately so that we = may correct our internal records. Please then delete the original message. = Thank you.

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