X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.103] (HELO ms-smtp-04-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 912888 for flyrotary@lancaironline.net; Sun, 24 Apr 2005 09:02:02 -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 j3OD1DL5010117 for ; Sun, 24 Apr 2005 09:01:15 -0400 (EDT) Message-ID: <000f01c548cd$b79f4090$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: V slot failure mode and Who knew? Date: Sun, 24 Apr 2005 09:01:23 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000C_01C548AC.30488140" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_000C_01C548AC.30488140 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageThe Hurley seals I installed in 2001 (150 hrs) were brand new. = The are now very worn, there is a groove underneath the rubbing service = the entire length of each seal - so deep on some of the seals that a = ridge of metal has been pushed up along the top of the groove. This is = where the seal rubs against the top edge of the seal slot. I recall = that one of the supposed benefits of these seals is that the were easier = on rotor housings - (because they were softer?). Based on the amount of = wear after 150 hours I think an apex seal failure (in my engine) was = inevitable before 300 hrs (just speculation based on amount of seal = wear). My personal opinion is a combination of softer seals and worn apex = grooves was my problem. If you have nice vertical apex slots then there = is almost no bending force on the seal and the seal slides up and down = in the slot supported by the wall. If the apex groove is wider at the = top (for whatever reason), there is a bending motion imparted to the = seal - the bottom of the slot is still at specs holding the bottom of = the apex seal in one plane, however when the combustion gases push on = the seal, the top portion of the seal is no longer supported (by the top = walls of the slot) in the same plane as the bottom. This imparts a bend = motion on the seal - being brittle it can not take much bending motion = before breaking - and all else follows. On the other hand if you have a stronger seal and one which withstand = some bending motion. IF that is part of the failure process then the = stronger seals will (in my opinion) almost certainly delay the failure. = To answer your question about having a "handle on where those? things = had been", not certain exactly which "things" you are referring to. My = engine was a JSpec engine imported from Japan - it was a turbo engine - = who knows how easily or hard it had been driven. However, since I used = 9.7:1 high compression rotors, we know they came out of a 89-91 NA 13B - = I have no idea what shape that engine was in.=20 NO, I did not check the apex seal slots - I certainly would have - had = I known then, what I know now {:>). They "looked" fine and I was = unaware of the "V" slot problem. =20 In fact, I dare say most of the subscribers (Lynn and a few others = excepted) to this list were unaware ot the "V" slot problem until my = "incident". So if there is any good that has come out of the = "incident", I think it is many more folks will check out the apex seal = slot much more carefully before putting them in an engine. Either you = are comfortably within specs, or you go the 3mm route or buy new rotors = (expensive I agree - but your butt is worth it). Perhaps, as I have stated, it was just a combination of factors (all = converging at the same time) that caused my failure - might not happen 1 = time out 100. It certainly has not done anything but convince me that = the rotary engine can fail (as can all things mechanical) - BUT, even = then it will get you back safely - what more can you ask of an = mechanical thing? Ed A ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Saturday, April 23, 2005 11:26 PM Subject: [FlyRotary] Re: rotor and seal wear was Re: All Parts have = arrived, Whew! Rusty and Ed got what - 100 hrs or so? Rusty's seals were worn, the = slots wallowed out beyond specs, Ed's slots wallowed out beyond specs, = etc. Granted both engines were built from cores, but didn't both have = a pretty good handle on "where those things had been"? =20 Hi Jim, Just need to correct a few facts. My engine was all new. No used = parts at all. The apex slots in the rotors are still just like new, but = the Hurley apex seal was considerably worn on the sides. Maybe the = slots were too tight? =20 Rusty ------=_NextPart_000_000C_01C548AC.30488140 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
The Hurley seals I installed in 2001 = (150 hrs) were=20 brand new.  The are now very worn, there is a groove underneath the = rubbing=20 service the entire length of each seal - so deep on some of the = seals that=20 a ridge of metal has been pushed up along the top of the groove.  = This is=20 where the seal rubs against the top edge of the seal = slot. =20  I recall that one of the supposed benefits of these seals is that = the were=20 easier on rotor housings - (because they were softer?).  Based on = the=20 amount of wear after 150 hours I think an apex seal failure (in my = engine) was=20 inevitable before 300 hrs (just speculation based on amount of seal=20 wear).
 
My personal opinion is a combination of = softer=20 seals and worn apex grooves was my problem.  If you have = nice=20 vertical apex slots then there is almost no bending force on the = seal and=20 the seal slides up and down in the slot supported by the = wall.   If=20 the apex groove is wider at the top (for whatever reason), there is a = bending=20 motion imparted to the seal - the bottom of the slot is still at specs = holding=20 the bottom of the apex seal in one plane, however when the combustion = gases push=20 on the seal, the top portion of the seal is no longer supported (by=20 the top walls of the slot) in the same plane as the = bottom. This=20 imparts a bend motion on the seal - being brittle it can not take much = bending=20 motion before breaking - and all else follows.
 
On the other hand if you have a = stronger seal and=20 one which withstand some bending motion.   IF that is part of the failure process then the stronger seals = will (in=20 my opinion) almost certainly delay the failure. 
 
To answer your question about having a = "handle on=20 where those? things had been", not certain exactly which "things" you = are=20 referring to.  My engine was  a JSpec engine imported from = Japan - it=20 was a turbo engine - who knows how easily or hard it had been=20 driven. However, since I used 9.7:1 high compression rotors, we = know they=20 came out of a 89-91 NA 13B - I have no idea what shape that engine was=20 in. 
 
 NO, I did not check the apex seal = slots - I=20 certainly would have -  had I known then, what I know now = {:>). =20 They "looked" fine and I was unaware of the "V" slot problem. =20
 
In fact, I dare say most of the = subscribers (Lynn=20 and a few others excepted) to this list were unaware ot the "V" slot = problem=20 until my "incident".  So if there is any good that has come out of = the=20 "incident", I think it is many more folks will check out the apex seal = slot much=20 more carefully before putting them in an engine.  Either you =  are=20 comfortably within specs, or you go the 3mm route or buy new rotors = (expensive I=20 agree - but your butt is worth it).
Perhaps, as I have stated, it was just = a=20 combination of factors (all converging at the same time) that caused my = failure=20 - might not happen 1 time out 100.  It certainly has not done = anything but=20 convince me that the rotary engine can fail (as can all things = mechanical) -=20 BUT, even then it will get you back safely - what more can you ask of an = mechanical thing?
 
Ed A
 
 
 
 
 
 
 
 
 
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Saturday, April 23, 2005 = 11:26=20 PM
Subject: [FlyRotary] Re: rotor = and seal=20 wear was Re: All Parts have arrived, Whew!

Rusty and Ed got what - 100 hrs or so?  Rusty's seals were = worn, the=20 slots wallowed out beyond specs, Ed's slots wallowed out beyond specs, = etc.  Granted  both engines were built from cores, but = didn't both=20 have a pretty good handle on "where those things had = been"?   
 
Hi=20 Jim,
 
Just need=20 to correct a few facts.  My engine was all new.  No used = parts at=20 all.  The apex slots in the rotors are still just like = new, but=20 the Hurley apex seal was considerably worn on the = sides.  Maybe=20 the slots were too tight?  
 
Rusty
 
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