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 5.0.8) with ESMTP id 988772 for flyrotary@lancaironline.net; Fri, 17 Feb 2006 09:04:05 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-025-165.carolina.res.rr.com [24.74.25.165]) by ms-smtp-04-eri0.southeast.rr.com (8.13.4/8.13.4) with SMTP id k1HE3EKE028654; Fri, 17 Feb 2006 09:03:17 -0500 (EST) Message-ID: <009201c633ca$a250c310$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" , "Chuck Dunlap" Cc: "Chuck Dunlap" References: Subject: Check Apex slots was Re: [FlyRotary] Another rotary failure Date: Fri, 17 Feb 2006 09:01:21 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_008F_01C633A0.B8E6DF80" 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_008F_01C633A0.B8E6DF80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageHi Chuck, Sorry to hear about your engine troubles, but glad the landing came out = a bit better this time. It sounds like to me you lost an apex seal. = When I lost mine last April on way to Sun & Fun, I lost power on one = rotor, there was some vibration - but not bad, the EGT on the bad rotor = dropped to 1200F or below. Also, I could maintain 4800 rpm (enough to = keep me level at 6000 msl), but I had to turn up the fuel flow to 14 GPH = to keep that rpm. Normally, that would give me around 160HP, so figured = I was getting around 70-80 HP. I have found that 67HP will keep me = airborne at 120 MPH IAS. Be certain and check the wear of your apex seal slots. If they get too = worn the apex seal lacks support from the side walls of the slot, will = lay over and drag against the rotor housing until the pressure simply = becomes too much and they break. When I tore my engine down I found what I believe was the cause. 1. One apex seal had broken with the center section of the seal leaving = its slot and the two ends remaining. 2. That broken piece flew back and caught the second apex seal down in = its slot and smeared the soft iron over the lip of the slot. That = prevented the second apex seal from coming up - so had no compression on = that rotor. 3. I found that the apex seals on my used rotor had wallowed out due = to wear and the walls of the apex slot instead of being vertical were = sloped in a "V". In other words, the rectangular shape of the slot had = turned into a "V" with the tops wider than the bottom of the slot. =20 4. The slots were worn out of tolerance which means the apex seal had = less and less support from the slot side walls and finally it became too = much and the seal broke. I was using Dave Atkins seals (same as = Hurley's) and when they were tested on a Rockwell tester the ones I had = turned out to be a bit softer than a comparison set they were measured = against. But, I think the main cause was the worn apex slots. 5. So I am convinced the use of worn rotors with worn-out slots = combined with softer seals was the end cause of the problem. I was just = not aware that there were limits on the slots (never really even thought = about it). But, after the incident, I did find in the Mazda overhaul = books a WARNING about using rotors with the "V"ing beyond a certain = limit - mine were. 6. I then purchased brand-new rotors and am using Tracy Crooks new = seals and thus far have had no problem. I also had some of my flying friends try to talk me into putting in a = Lycoming, but I asked them how many lycomings had they seen fly back = with two cylinders out of operation. No, while I was certainly not = happy about it, the performance on one rotor convinced me that the = rotary is the way to go. By the way, there was no damage to the rotor housings or side housings = in my case. The one rotor did have a corner cracked where the broken = part of the seal smeared over the following apex seal area. Otherwise, = I could have reused the rotor (NOT!) assuming it had not been worn = beyond the spec limit . Hopefully, you won't have that problem. Good luck in your rebuild - its a pain doing it in a rotor no-man's = land. Been there, done that. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ----- Original Message -----=20 From: Chuck Dunlap=20 To: Rotary motors in aircraft=20 Sent: Sunday, February 12, 2006 12:26 AM Subject: [FlyRotary] Another rotary failure Sorry I didn't make to Bill Eslick's for the Rotorfest, I missed by = about one hour. About 30 miles north of San Angelo TX the RPM suddenly = dropped and I could not restore it with any of my emergency procedures. = GPS told me nearest airport was Robert Lee about 15 miles away. I headed = there and landed without incident. Turning the prop by hand shows almost zero compression in one rotor, = indicating bad/broken apex seals, quite similar to my engine-out = experience 2 1/2 years ago which caused a forced landing near the Grand = Canyon. This time the vibration was not quite as bad, and the RPM = dropped to around 4300 which was still not enough to maintain altitude. = I called my friend with a Glasair and he cam got me and took me home. I = will have to find some time to build another motor and drive 12 hours = back there and swap motors. Or I might drive there, remove the wings and = trailer it back, have not decided yet. My good friend/mentor/flight instructor is trying to talk me into = going back to a Lycosaurus, and I have to think of some good reasons not = to. Until I get the motor back and torn apart, I wont know what caused = the failure, but I will post anything that I find. Regards Chuck Dunlap RV-6 13B 535 hours ------=_NextPart_000_008F_01C633A0.B8E6DF80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Hi Chuck,
 
Sorry to hear about your engine troubles, but = glad the=20 landing came out a bit better this time.  It sounds like to me you = lost an=20 apex seal.  When I lost mine last April on way to Sun & Fun, I = lost=20 power on one rotor, there was some vibration - but not bad, the EGT on = the bad=20 rotor dropped to 1200F or below.  Also, I could maintain 4800 rpm = (enough=20 to keep me level at 6000 msl), but I had to turn up the fuel flow to 14 = GPH to=20 keep that rpm.  Normally, that would give me around 160HP, so = figured I was=20 getting around 70-80 HP.  I have found that 67HP will keep me = airborne at=20 120 MPH IAS.
 
Be certain and check the wear of your apex seal=20 slots.  If they get too worn the apex seal lacks support from the = side=20 walls of the slot, will lay over and drag against the rotor housing = until the=20 pressure simply becomes too much and they break.
 
When I tore my engine down I found what I = believe was the=20 cause.
 
1.  One apex seal had broken with the = center section=20 of the seal leaving its slot and the two ends remaining.
2.  That broken piece flew back and caught = the second=20 apex seal down in its slot and smeared the soft iron over the lip of the = slot.  That prevented the second apex seal from coming up - so had = no=20 compression on that rotor.
3.  I found that the apex seals on my used=20 rotor  had wallowed out due to wear and the walls of the apex slot = instead=20 of being vertical were sloped in a "V".  In other words, the = rectangular=20 shape of the slot had turned into a "V" with the tops wider than the = bottom of=20 the slot. 
 
4.  The slots were worn out of tolerance = which means=20 the apex seal had less and less support from the slot side walls and = finally it=20 became too much and the seal broke.  I was using Dave Atkins seals = (same as=20 Hurley's) and when they were tested on a Rockwell tester the ones I had = turned=20 out to be a bit softer than a comparison set they were measured = against. =20 But, I think the main cause was the worn apex slots.
 
5.  So I am convinced the use of worn = rotors with=20 worn-out slots combined with softer seals was the end cause of the=20 problem.  I was just not aware that there were limits on the slots = (never=20 really even thought about it).  But, after the incident, I did find = in the=20 Mazda overhaul books a WARNING about using rotors with the "V"ing beyond = a=20 certain limit - mine were.
 
6.  I then purchased brand-new rotors and = am using=20 Tracy Crooks new seals and thus far have had no problem.
 
I also had some of my flying friends try to talk = me into=20 putting in a Lycoming, but I asked them how many lycomings had they seen = fly=20 back with two cylinders out of operation.  No, while I was = certainly not=20 happy about it, the performance on one rotor convinced me that the = rotary is the=20 way to go.
 
By the way, there was no damage to the rotor = housings or=20 side housings in my case.  The one rotor did have a corner cracked = where=20 the broken part of the seal smeared over the following apex seal = area. =20 Otherwise, I could have reused the rotor (NOT!) assuming it had not been = worn=20 beyond the spec limit
.
Hopefully, you won't have that = problem.
 
Good luck in your rebuild - its a pain doing it = in a rotor=20 no-man's land.  Been there, done that.
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary = Powered
Matthews,=20 NC
eanderson@carolina.rr.com
----- Original Message -----
From:=20 Chuck = Dunlap=20
Sent: Sunday, February 12, 2006 = 12:26=20 AM
Subject: [FlyRotary] Another = rotary=20 failure

Sorry I didn't=20 make to Bill Eslick's for the Rotorfest, I missed by about one hour. = About 30=20 miles north of San Angelo TX the RPM suddenly dropped and I could not = restore=20 it with any of my emergency procedures. GPS told me nearest airport = was Robert=20 Lee about 15 miles away. I headed there and landed without=20 incident.
Turning the prop=20 by hand shows almost zero compression in one rotor, indicating = bad/broken apex=20 seals, quite similar to my engine-out experience 2 1/2 years ago which = caused=20 a forced landing near the Grand Canyon. This time the vibration was = not quite=20 as bad, and the RPM dropped to around 4300 which was still not enough = to=20 maintain altitude.  I called my friend with a Glasair and he cam = got me=20 and took me home. I will have to find some time to build another motor = and=20 drive 12 hours back there and swap motors. Or I might drive there, = remove the=20 wings and trailer it back, have not decided yet.
My = good=20 friend/mentor/flight instructor is trying to talk me into going back = to a=20 Lycosaurus, and I have to think of some good reasons not to. Until I = get the=20 motor back and torn apart, I wont know what caused the failure, = but I=20 will post anything that I find.
 
Regards
Chuck=20 Dunlap
RV-6 = 13B 535=20 hours
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