X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from EXHUB003-4.exch003intermedia.net ([207.5.74.111] verified) by logan.com (CommuniGate Pro SMTP 5.3.5) with ESMTPS id 4222878 for flyrotary@lancaironline.net; Thu, 15 Apr 2010 15:52:44 -0400 Received-SPF: none receiver=logan.com; client-ip=207.5.74.111; envelope-from=jwhaley@datacast.com Received: from EXVMBX003-5.exch003intermedia.net ([207.5.74.45]) by EXHUB003-4.exch003intermedia.net ([207.5.74.111]) with mapi; Thu, 15 Apr 2010 12:52:09 -0700 From: Jeff Whaley To: Rotary motors in aircraft Date: Thu, 15 Apr 2010 12:53:02 -0700 Subject: RE: [FlyRotary] Re: Weird sound during descent Thread-Topic: [FlyRotary] Re: Weird sound during descent Thread-Index: Acrcxd5mlhEpwB/aTFeJdPtHR+gwtwADmFiw Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_C03ABB0A7362B84BB53D544B3C305E0E017944BEAD34EXVMBX0035e_" MIME-Version: 1.0 --_000_C03ABB0A7362B84BB53D544B3C305E0E017944BEAD34EXVMBX0035e_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable The controls are pretty tight, plus the ailerons and flaps are skinned with= corrugated aluminum - maybe the corrugation bumps are reacting to the airf= low like a whistle? Jeff From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of David Staten Sent: Thursday, April 15, 2010 2:02 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Weird sound during descent Is there any free play in the control surfaces that could cause a flutterin= g of the surface that you dont hear when power/noice is higher? On Thu, Apr 15, 2010 at 10:13 AM, Jeff Whaley > wrote: 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 z= zuuzz, 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 th= at lifted me against the seat belts -- the noise stopped. Tracy had cautioned me against low power steeps descents, something about t= hrust 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 wh= at 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 signatur= e 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 a= ddressee and may contain privileged or confidential information. Any unauth= orized 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. __________ Information from ESET NOD32 Antivirus, version of virus signatur= e database 5031 (20100415) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signatur= e 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 a= ddressee and may contain privileged or confidential information. Any unauth= orized 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. --_000_C03ABB0A7362B84BB53D544B3C305E0E017944BEAD34EXVMBX0035e_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

The controls are pretty tight, plus the ailerons and flaps a= re skinned with corrugated aluminum – maybe the corrugation bumps are= reacting to the airflow like a whistle?

Jeff

 

From: Rotary m= otors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Staten
Sent: Thursday, April 15, 2010 2:02 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Weird sound during descent

 

Is there any free pla= y in the control surfaces that could cause a fluttering of the surface that= you dont hear when power/noice is higher?

On Thu, Apr 15, 2010 at 10:13 AM, Jeff Whaley <jwhaley@datacast.com> wrote:

I have been hearing a weird buzzing sound usually detectable on ba= se leg at low power settings.  It is hard to describe in text but is r= epeatedly 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-sty= le gear.

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

Tracy had cautioned me against low power steeps descents, somethin= g 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?<= /o:p>

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

Jeff



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The message was checked by ESET NOD32 Antivirus.

http://www.eset.com<= br>
This message, and the documents attached hereto, is i= ntended only for the addressee and may contain privileged or confidential i= nformation. Any unauthorized disclosure is strictly prohibited. If you have received this message in error, please notify us immediately s= o that we may correct our internal records. Please then delete the original= message. Thank you.

 

 

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

 

The message was checked by ESET NOD32 Antivirus.

 

http://www.eset.com



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The message was checked by ESET NOD32 Antivirus.

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This message, and the docum= ents attached hereto, is intended only for the addressee and may contain pr= ivileged or confidential information. Any unauthorized disclosure is strict= ly 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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