X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 912081 for flyrotary@lancaironline.net; Sat, 23 Apr 2005 07:50:22 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; 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-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j3NBnX0W020928 for ; Sat, 23 Apr 2005 07:49:35 -0400 (EDT) Message-ID: <000a01c547fa$89984120$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: All Parts have arrived, Whew! Date: Sat, 23 Apr 2005 07:49:42 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0007_01C547D9.024886B0" 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_0007_01C547D9.024886B0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Well, a bit of wobble can indeed break apex seals - that is one of the = failure modes. Its just I didn't think my seal slots were that worn - = however after finding the were in some cases past the 0.15mm limit set = by Mazda, I think it possible that the stresses from the "leaned over" = profile broke the brittle seal. I had not measured the compression = since last year at the annual inspection - so don't know what it was, = but I agree it seemed good based on the rpm and power. However, a slop = apex seal slot will not necessarily show up as low compression - it may = still seal - but under more stress due to the angle. However, it could have been an foreign object, don't know what it would = have been at 7000 msl. Don't see where anything could have laid around = in the intake through my max power take off and then break loose. = Besides, there is nothing missing. The things it could have been was a = chunk of my plastic manifold - no pieces missing, the epoxy shaping the = secondary intake ports in the lower manifold - inspected and all there. I could find not scrape mark or impression on the rotor housing with the = broken seal - which surprised me. I will inspect the rotor housings = more carefully after I get the engine back together in case I missed it. I looked at the four spark plugs again yesterday for missing pieces of = ceramic cone, chunks of electrode, etc. These are Racing plugs and seem = fairly well constructed and nothing was missing. I will be sticking = them back in the new engine - after I found their electrode is at least = 5mm from the combustion chamber. Just a coincident that the engine = broke right after I put the new spark plugs in - perhaps I was = generating more power with the new unshrouded plugs and broke the seals = {:>). So may never know for certain - could have been just a combination of = things adding up, weak fractured seal, sloppy apex slot, etc. could have = been the dust. Ed ----- Original Message -----=20 From: Finn Lassen=20 To: Rotary motors in aircraft=20 Sent: Friday, April 22, 2005 11:27 PM Subject: [FlyRotary] Re: All Parts have arrived, Whew! You all have to remember that Ed has a knack for finding and exploring = all possible failure modes - known, unknown, and yes, even the = impossible :) Something that no one has memtioned is the gears (end = housings/rotors). Also rotor bearings/e-shaft clearance. What's the consequences of out-of tolerances here? I just can't see that a bit of wobble of the apex seals in their = grooves could cause a seal to break. Also, how could you have such excellent compression with worn = seals/grooves? Sounds more like a fluke or foreign object to me. Any chance that some = carbon build-up near exhaust ports could break loose and get jammed = between seal and edge of exhaust port? Any telltale on the rotor housing as to where the seal broke? Did you *thoroughly* inspect the four sparkplugs? Any piece of metal = or porcelain missing at all? Finn Ed Anderson wrote: Well, George, I would not take the conclusion that far. We have = folks flying with several hundred more hours than I have with no apex = seal failures. In fact to the best of my knowledge, I am the only one I = am aware of other than Chuck Dunlap who's rotary engine swallowed a 1/4" = dia steel bolt (it was retained - so we know) to have an apex seal = failure in an aircraft. However, I do believe that folks need to be = more aware of the true condition of their used engine components - I = know all probably did was look at it and not seeing any obviously = defects or dings said - "good to go!" As you know, Leon is convinced my apex seal failure was also due to = foreign object ingestion - I certainly can not prove it was something = else (like the apex seal slop) although I don't believe a foreign = object to be the case - belief is not a fact {:>).=20 Ed ------=_NextPart_000_0007_01C547D9.024886B0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Well, a bit of wobble can indeed break = apex seals -=20 that is one of the failure modes.  Its just I didn't think my seal = slots=20 were that worn - however after finding the were in some cases past the = 0.15mm=20 limit set by Mazda, I think it possible that the stresses from the = "leaned over"=20 profile broke the brittle seal.  I had not measured the compression = since=20 last year at the annual inspection - so don't know what it was, but I = agree it=20 seemed good based on the rpm and power.  However, a slop apex seal = slot=20 will not necessarily show up as low compression - it may still seal - = but under=20 more stress due to the angle.
 
However, it could have been an foreign = object,=20 don't know what it would have been at 7000 msl.  Don't see where = anything=20 could have laid around in the intake  through my max power take off = and=20 then break loose.  Besides, there is nothing missing.  The = things it=20 could have been was a chunk of my plastic manifold - no pieces missing, = the=20 epoxy shaping the secondary intake ports in the lower manifold - = inspected and=20 all there.
 
I could find not scrape mark or = impression on the=20 rotor housing with the broken seal - which surprised me.  I will = inspect=20 the rotor housings more carefully after I get the engine back together = in case I=20 missed it.
 
I looked at the four spark plugs again = yesterday=20 for missing pieces of ceramic cone, chunks of electrode, etc.  = These are=20 Racing plugs and seem fairly well  constructed and nothing was=20 missing.  I will be sticking them back in the new engine  - = after I=20 found their electrode is at least 5mm from the combustion chamber.  = Just a=20 coincident that the engine broke right after I put the new spark plugs = in -=20 perhaps I was generating more power with the new unshrouded plugs and = broke the=20 seals {:>).
 
So may never know for certain - could = have been=20 just a combination of things adding up, weak fractured seal, sloppy apex = slot,=20 etc. could have been the dust.
 
Ed
----- Original Message -----
From:=20 Finn=20 Lassen
Sent: Friday, April 22, 2005 = 11:27=20 PM
Subject: [FlyRotary] Re: All = Parts have=20 arrived, Whew!

You all have to remember that Ed has a knack for = finding and=20 exploring all possible failure modes - known,  unknown, and yes, = even the=20 impossible :)

Something that no one has memtioned is the gears = (end=20 housings/rotors).
Also rotor bearings/e-shaft clearance.
What's = the=20 consequences of out-of tolerances here?
I just can't see that a bit = of=20 wobble of the apex seals in their grooves could cause a seal to=20 break.
Also, how could you have such excellent compression with = worn=20 seals/grooves?
Sounds more like a fluke or foreign object to me. = Any chance=20 that some carbon build-up near exhaust ports could break loose and get = jammed=20 between seal and edge of exhaust port?
Any telltale on the rotor = housing as=20 to where the seal broke?
Did you *thoroughly* inspect the four = sparkplugs?=20 Any piece of metal or porcelain missing at all?

Finn

Ed = Anderson=20 wrote:
Well, George, I would not =  take the=20 conclusion that far.  We have folks flying with several hundred = more=20 hours than I have with no apex seal failures.  In fact to the = best of=20 my knowledge, I am the only one I am aware of other than Chuck = Dunlap who's=20 rotary engine swallowed a 1/4" dia steel bolt (it was retained - so = we know)=20 to have an apex seal failure in an aircraft.  However, I do = believe=20 that folks need to be more aware of the true condition of their used = engine=20 components - I know all probably did was look at it and not seeing = any=20 obviously defects or dings said - "good to go!"
 
As you know, Leon is = convinced my=20 apex seal failure was also due to foreign object ingestion - I = certainly can=20 not prove it was something else (like the apex seal slop)  = although I don't believe a foreign object  to be the case = - belief=20 is not a fact {:>). 
 
 
Ed
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