X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from S3.cableone.net ([24.116.0.229] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 1036994 for flyrotary@lancaironline.net; Fri, 17 Mar 2006 00:22:41 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.116.0.229; envelope-from=crayd@cableone.net Received: from chuckathlon (unverified [69.92.218.28]) by S3.cableone.net (CableOne SMTP Service S3) with ESMTP id 49962828 for ; Thu, 16 Mar 2006 22:59:10 -0700 Return-Path: From: "Chuck Dunlap" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Motor teardown results Date: Thu, 16 Mar 2006 22:23:33 -0700 Message-ID: <00e101c64982$efa175b0$6501a8c0@chuckathlon> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00E2_01C64948.43429DB0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.3416 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2727.1300 In-Reply-To: Importance: Normal X-NotAscii: charset=us-ascii X-IP-stats: Incoming Last 1, First 15, in=2, out=0, spam=0 X-External-IP: 69.92.218.28 X-Abuse-Info: Send abuse complaints to abuse@cableone.net This is a multi-part message in MIME format. ------=_NextPart_000_00E2_01C64948.43429DB0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable =20 I have not thought about it until now :-) I always thought 3mm was for turbo motors to avert detonation damage, or as a way to salvage rotors with worn slots. Chuck=20 =20 - Chuck have you thought to go to 3mm? George ( down under) =20 =20 I finally got time to get my failed 13b apart. The rear rotor was missing one apex seal, the other 2 were intact but jammed due to the fragments of the broken one. The rotor housing has the classic chatter marks all around. Doing a Google of "13B apex seal chatter" results in plenty of examples of this failure mode. Apparently the chatter is from the natural resonant frequency of the seal, it eventually fatigues the seal causing failure. The front rotor was in good shape, but the housing had the same chatter marks, but not as severe as the rear rotor. The front rotor housing was brand new 150 hours ago when I rebuilt this motor after the Grand Canyon forced landing. At that time the good rotor housing had slight chatter marks but I reused it. The front rotor was destroyed at that time due to foreign object entering the rotor. Both rotors were missing the corner seal rubber plugs on the side with the short apex seal segment. Perhaps the small segment vibrated more, disintegrating the rubber seals? The first 260 hours of flying my rotary bird was with stock 3-piece seals, and I never saw any chatter marks. The last 250 hours has been flown with 2 piece seals and now I have chatter marks . I now have Tracy's 2 piece apex seals and I wonder how they will perform, it appears that the heavier weight of the 2 piece seals puts the resonant frequency in the cruising range of 6000RPM? =20 Chuck Dunlap RV6 13B _____ =20 -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ------=_NextPart_000_00E2_01C64948.43429DB0 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable Message
 
I  = have not=20 thought about it until now :-) I always thought 3mm was for turbo = motors to=20 avert detonation damage, or as a way to salvage rotors with worn=20 slots.
Chuck 
 
- Chuck have you thought to go to = 3mm?
George ( down under)
 
 
I = finally got=20 time to get my failed 13b apart. The rear rotor was missing one apex = seal,=20 the other 2 were intact but jammed due to the fragments of the = broken one.=20 The rotor housing has the classic chatter marks all around. Doing a = Google=20 of "13B apex seal chatter" results in plenty of examples of this = failure=20 mode. Apparently the chatter is from the natural resonant frequency = of the=20 seal, it eventually fatigues the seal causing = failure.
The front rotor=20 was in good shape, but the housing had the same chatter marks, but = not as=20 severe as the rear rotor. The front rotor housing was brand new 150 = hours=20 ago when I rebuilt this motor after the Grand Canyon forced landing. = At that=20 time the good rotor housing had slight chatter marks but I reused = it. The=20 front rotor was destroyed at that time due to foreign object = entering the=20 rotor.
Both rotors were=20 missing the  corner seal rubber plugs on the side with the = short apex=20 seal segment. Perhaps the small segment vibrated more, = disintegrating the=20 rubber seals?
The first 260=20 hours of flying my rotary bird was with stock 3-piece seals, and I = never saw=20 any chatter marks. The last 250 hours has been flown with 2 piece = seals and=20 now I have chatter marks .
I = now have=20 Tracy's 2 piece apex seals and I wonder how they will perform, it = appears=20 that the heavier weight of the 2 piece seals puts the resonant = frequency in=20 the cruising range of 6000RPM?
 
Chuck=20 Dunlap
RV6=20 13B

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Homepage:  http://www.flyrotary.com/
Archive = and=20 UnSub:  =20 = http://mail.lancaironline.net/lists/flyrotary/
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