X-Virus-Scanned: clean according to Sophos on Logan.com X-PolluStop-Diagnostic: ####\eX-PolluStop-Score: 0.46\eX-PolluStop: Scanned with Niversoft PolluStop 2.1 RC1, http://www.niversoft.com/pollustop Return-Path: Received: from [24.25.9.103] (HELO ms-smtp-04-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c4) with ESMTP id 869085 for flyrotary@lancaironline.net; Thu, 14 Apr 2005 15:51:46 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-185-127.carolina.res.rr.com [24.74.185.127]) by ms-smtp-04-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j3EJovL5002645 for ; Thu, 14 Apr 2005 15:50:58 -0400 (EDT) Message-ID: <000801c5412b$4bd4bec0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" Subject: V shape Apex Seal Slots? Date: Thu, 14 Apr 2005 15:51:05 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0005_01C54109.C4660AA0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0005_01C54109.C4660AA0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Well, I continue to gather more information on the seal failure. I = measured the apex seal slot width at it bottom (where you would expect = little wear) and at its top. These are the results on the "good" rotor, = I didn't bother with the "bad" rotor. Apex Location Base Top Seal1 1.99mm 2.16 - 2.26mm Seal2 1.98mm 2.22 - 2.25mm Seal3 1.98mm 2.18 - 2.20mm Clearly the slot is larger at the top - is this due to design or is this = due to wear? Lynn??? Anybody? In any case I found the specs for the space left between seal and slot = side after you stick an Apex seal in the slot, again in the good rotor = (I used a new seal), the max limit permitted (specs) is 0.15mm, ALL the = slots would accept a 0.15mm leaf gauge blade between the seal and top of = the apex slot and some would accept a 0.18mm blade. Clearly at or = outside the max limits. As I rotated the rotors around their housings before I completely = disassembled the engine, I noticed that the apex seals seemed to be = leaning quite a bit as they brushed along the housing walls. I think = these measurements indicate I either got a rotor set that was on its = last legs or something cause abnormal wear. Since the rotors were used, = I have no ideal how many miles or how hard the miles may have been. I = have read that apex slots can become worn sufficiently that the apex = seal will fold over the edge - and a piece of one apex seal certainly = did. The question is did it fold over due to a foreign object first breaking = the seal or did the seal break because its center section was = encountering increased drag and bending motion compared to its ends? = The ends stayed in place. Upon closer examination it appears there are faint "chatter" marks on = the inside of the rotor housings, you can see them visually and when I = move my fingers over them I can detect a very faint variation like a = wave pattern. The rotors were used also and I certainly don't recall = after 4 years - but they could have been present then. Fortunately, I = do have a set of practically brand new rotor housings - although they = are not turbo housings - well, the plus side may be easier to muffler = {:>) At this point I am inclined toward new rotors to h___l with the expense. = I'm going to get hemorrhoids if this keeps up {:>). =20 Just though you would like to know. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ------=_NextPart_000_0005_01C54109.C4660AA0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Well, I continue to gather more = information on the=20 seal failure.  I measured the apex seal slot width at it bottom = (where you=20 would expect little wear) and at its top.  These are the results on = the=20 "good" rotor, I didn't bother with the "bad" rotor.
 
Apex Location    =    =20     Base        =    =20 Top
 
Seal1    =    =20               =  =20 1.99mm        2.16 - 2.26mm
Seal2    =    =20             =    =20 1.98mm        2.22 - 2.25mm
Seal3    =    =20             =    =20 1.98mm        2.18 - 2.20mm
 
Clearly the slot is larger at the top - = is this due=20 to design or is this due to wear?  Lynn??? Anybody?
 
In any case I found the specs for the = space left=20 between seal and slot side after you stick an Apex seal in the slot, = again in=20 the good rotor (I used a new seal), the max limit permitted (specs) is=20 0.15mm,  ALL the slots would accept a 0.15mm leaf gauge blade = between the=20 seal and top of the apex slot and some would accept a 0.18mm = blade. =20 Clearly at or outside the max limits.
 
As I rotated the rotors around their = housings=20 before I completely disassembled the engine, I noticed that the apex = seals=20 seemed to be leaning quite a bit as they brushed along the housing=20 walls.  I think these measurements indicate I either got a rotor = set=20  that was on its last legs or something cause abnormal wear.  = Since=20 the rotors were used, I have no ideal how many miles or how hard the = miles may=20 have been.  I have read that apex slots can become worn = sufficiently that=20 the apex seal will fold over the edge - and a piece of one apex seal = certainly=20 did.
 
The question is did it fold over due to = a foreign=20 object first breaking the seal or did the seal break because its center = section=20 was encountering increased drag and bending motion compared to its = ends? =20 The ends stayed in place.
 
  Upon closer examination it = appears there are=20 faint  "chatter" marks on the inside of the rotor housings, you can = see=20 them visually and when I move my fingers over them I can detect a very = faint=20 variation like a wave pattern.   The rotors were used = also and=20  I certainly don't recall after 4 years - but they could have been = present=20 then.  Fortunately, I do have a set of practically brand new rotor = housings=20 - although they are not turbo housings - well, the plus side may be = easier to=20 muffler {:>)
 
At this point I am inclined toward new = rotors to=20 h___l with the expense.  I'm going to get hemorrhoids if this keeps = up=20 {:>). 
 
Just though you would like to = know.
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.com
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