Return-Path: Received: from mailout1.pacific.net.au ([61.8.0.84] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 573273 for flyrotary@lancaironline.net; Sun, 19 Dec 2004 16:21:08 -0500 Received-SPF: none receiver=logan.com; client-ip=61.8.0.84; envelope-from=peon@pacific.net.au Received: from mailproxy1.pacific.net.au (mailproxy1.pacific.net.au [61.8.0.86]) by mailout1.pacific.net.au (8.12.3/8.12.3/Debian-7.1) with ESMTP id iBJLKaGx001898 for ; Mon, 20 Dec 2004 08:20:36 +1100 Received: from ar1 (ppp201C.dyn.pacific.net.au [61.8.32.28]) by mailproxy1.pacific.net.au (8.12.3/8.12.3/Debian-7.1) with SMTP id iBJLKWcG030128 for ; Mon, 20 Dec 2004 08:20:32 +1100 Message-ID: <004e01c4e610$90de00b0$1c20083d@ar1> From: "Leon" To: "Rotary motors in aircraft" References: Subject: Engine Failure modes was Re: [FlyRotary] Engine damage thoughts Date: Mon, 20 Dec 2004 08:20:28 +1100 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0049_01C4E66C.C3663B90" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 This is a multi-part message in MIME format. ------=_NextPart_000_0049_01C4E66C.C3663B90 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageYo Rusty, My experience has been that there are 2 basic failure modes when oil = pressure is lost. 1. At heavy loads and high RPM, (as in race engines at WOT) the main = problem is that the side housings require oil spill from the rotors to = cool them. Should the oil flow stop, and the engine continue to be = held at full throttle (which is not your scenario), the side housings = close to the crank hole tend to get hot and buckle like a belville = washer, and in the process grip the rotors like a vice and cause the = engine to seize. =20 I've even had a couple of blokes come to me saying that they have = experienced total lockup on the open road. This usually occurs due to = oil surge on long sweeping corners at high speed (esp long expressway = sweepers in the middle of the night!) when the oil level is low (coz = the owner hadn't checked it for the last 3 months!!), and it uncovers = the pick-up. Lockup can occur within 10 -15 seconds of losing oil pressure at WOT. = If the driver isn't smart enough to de-clutch immediately, the back = wheels will remain locked, and flatspot the tyres all the way to the = steel belts as the car spins out of control into whatever happens to be = on the side of the road! Scary Stuff!! Even if the engine doesn't seize, it will have badly scuffed oil = control rings and the side housings. Additionally, there is obviously = always bearing damage, but normally, the engine will lock up on the = side houings before it will seize on the bearings. The next time you start the engine, it will blow copious amount of oil = smoke for ever. The only solution is to split the engine, re-machine = the faces and fit new oil control rings and bearings. However, as you = took the power off the instant you noticed the oil leak, I don't think = this would have happened to your engine. (Whew he says!!). 2. If the engine loses oil pressure say at idle, or low RPM, the most = likely damage is that it will pick up the front stationary gear bearing. = If the engine is run at moderate speeds and light load, it can also = pick up on the rotor bearings on occasion, sometimes causing them to = spin in the rotors, but the front gear bearing is usually the first to = grab. So there are the two worst case failure modes you can expect. From what = you have described, I would think that there would be very little = damage, if any. After all, even though the cooler was leaking, there = appears to have been some oil flow, and you took the load off the = engine the isntant you noticed the leak. I would suspect that if there = is any damage, it will only be light scuffing or wiping of the bearings. The only REAL way to know is to split the engine and inspect it. = However, first do some simple preliminary diagnosis. Open up the oil = filter as Lynn suggested, and if it doesn't have any metal in it, the = the engine is probably OK. As a second check, make a small loop in a = piece of wire, and scrape the bottom of the sump through the drain = plug. =20 If you have internal damage, you will get metal deposits (babbitt metal = any maybe some copper) on the wire loop. Thirdly, if there happens to = be fine metal in the oil, you will be able to see it in a bottle = backlit with strong sunlight. If the oil is black, put some on a sheet = of plastic or Gladwrap and view it via transmitted light. Generally has = the appearance of metalflake paint. An oil analysis will pick up any = occult metal that is too fine to be seen with the naked eye. If all is clear, then the engine is probably not damaged, so fit a new = filter, re-fill with oil, start her up and do a couple of = precautionary filghts as you suggested below. Cheers, Leon. ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Sunday, December 19, 2004 4:36 AM Subject: [FlyRotary] Engine damage thoughts Greetings again, I've been thinking more about the engine, and wondering what the = chances are that there's any damage inside. =20 I'm pretty sure I noticed the oil about the instant it started to lose = any significant amount. As soon as the oil started to leak, I pulled = the engine back to idle, and descended ASAP. I'm sure I was doing at = least 2000 fpm from 6000 to 2000 ft, which only accounts for 2 minutes = of time. At 2000 ft, is when I tried to throttle up, and the engine = quit, so no time after that counts. I'm absolutely sure the engine quit = because I had the mixture knob set way lean for cruise, and not because = it seized up. =20 This means that at worst, the engine idled for 2 minutes with no oil = pressure. My guess would be that it was more like 30 seconds or less. = With this in mind, I'm thinking that it's worth doing some ground runs = of the engine to see how healthy it seems. If I can thoroughly run it = on the ground without problems, then I can follow that with about 10 = hours of circling the field. By that point, I can't imagine having any = further concerns. If there was a problem, it would damage the engine = further, but still continue to until I made it to an airport. If I'm = wrong about how much damage there might be, it will get expensive, but = shouldn't be life threatening. =20 Many of you have a lot more experience with these engines than I do. = Does this sound like a reasonable plan? Thanks, Rusty (late for the airport as always) ------=_NextPart_000_0049_01C4E66C.C3663B90 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Yo Rusty,
 
My experience has been that there are 2 = basic=20 failure modes when oil pressure is lost.
 
1.  At heavy loads and high = RPM, (as in=20 race engines at WOT) the main problem is that the side housings = require oil=20 spill from the rotors to cool them.  Should the oil flow = stop,  and=20 the engine continue to be held at full throttle (which is not your=20 scenario),  the side housings close to the crank hole tend to = get hot=20 and buckle like a belville washer,  and in the process grip the = rotors like=20 a vice and cause the engine to seize. 
 
I've even had a couple of blokes come = to me saying=20 that they have experienced total lockup on the open road.  This = usually=20 occurs due to oil surge on long sweeping corners at high speed (esp long = expressway sweepers in the middle of the night!)  when the oil = level=20 is low (coz the owner hadn't checked it for the last 3 months!!),  = and it=20 uncovers the pick-up.
 
Lockup can occur within 10 -15 = seconds of=20 losing oil pressure at WOT.  If the driver isn't smart enough to = de-clutch=20 immediately,  the back wheels will remain locked, and flatspot = the=20 tyres all the way to the steel belts as the car spins out of control = into=20 whatever happens to be on the side of the road! Scary = Stuff!!
 
Even if the engine doesn't seize,  = it=20 will have badly scuffed oil control rings and the side=20 housings. Additionally,  there is obviously = always bearing=20 damage,  but normally,  the engine will lock up on the side = houings=20 before it will seize on the bearings.
 
The next time you start the = engine,  it will=20 blow copious amount of oil smoke for ever.  The only solution is to = split=20 the engine,  re-machine the faces and fit new oil control rings and = bearings. However,  as you took the power off the instant you = noticed the=20 oil leak,  I don't think this would have happened to your engine. = (Whew he=20 says!!).
 
2.   If the engine loses oil = pressure say=20 at idle, or low RPM,  the most likely damage is that it will = pick up=20 the front stationary gear bearing.  If the engine is run at = moderate speeds=20 and light load,  it can also pick up on the rotor bearings on=20 occasion,  sometimes causing them to spin in the rotors,  but = the=20 front gear bearing is usually the first to grab.
 
So there are the two worst=20 case failure modes you can=20 expect.  From what you have described,  I would think that = there would=20 be very little damage,  if any.  After all,  even though = the=20 cooler was leaking,  there appears to have been some oil = flow,  and=20 you took the load off the engine the isntant you noticed the leak.  = I would=20 suspect that if there is any damage, it will only be light scuffing or = wiping of=20 the bearings.
 
The only REAL way to know is to = split the=20 engine and inspect it.  However,  first do some simple=20 preliminary diagnosis.  Open up the oil filter as Lynn=20 suggested,  and if it doesn't have any metal in it,  the the = engine is=20 probably OK.  As a second check,  make a small loop in a piece = of=20 wire,  and scrape the bottom of the sump through the drain = plug. =20
 
If you have internal damage,  you = will get=20 metal deposits (babbitt metal any maybe some copper) on the wire=20 loop.  Thirdly,  if there happens to be fine metal = in the=20 oil,  you will be able to see it in a bottle backlit with strong=20 sunlight.  If the oil is black,  put some on a sheet of = plastic or=20 Gladwrap and view it via transmitted light. Generally has the = appearance of=20 metalflake paint. An oil analysis will pick up any occult metal = that is too=20 fine to be seen with the naked eye.
 
If all is clear,  then the engine = is probably=20 not damaged,  so fit a new filter,  re-fill with = oil,  start=20 her up and do a couple of precautionary filghts as you suggested=20 below.
 
Cheers,
 
Leon.
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Sunday, December 19, 2004 = 4:36=20 AM
Subject: [FlyRotary] Engine = damage=20 thoughts

Greetings=20 again,
 
I've been = thinking more=20 about the engine, and wondering what the chances are that there's any = damage=20 inside. 
 
I'm pretty = sure I noticed=20 the oil about the instant it started to lose any significant = amount.  As=20 soon as the oil started to leak, I pulled the engine back to idle, and = descended ASAP.  I'm sure I was doing at least 2000 fpm from = 6000 to=20 2000 ft, which only accounts for 2 minutes of time.  At 2000 ft, = is when=20 I tried to throttle up, and the engine quit, so no time after that=20 counts.  I'm absolutely sure the engine quit because I had = the=20 mixture knob set way lean for cruise, and not because it seized = up. =20
 
This means = that at worst,=20 the engine idled for 2 minutes with no oil pressure.  My guess = would be=20 that it was more like 30 seconds or less.  With this in mind, I'm = thinking that it's worth doing some ground runs of the engine to see = how=20 healthy it seems.  If I can thoroughly run it on the ground = without=20 problems, then I can follow that with about 10 hours of circling the=20 field.  By that point, I can't imagine having any further = concerns. =20 If there was a problem, it would damage the engine further, but still = continue=20 to until I made it to an airport.  If I'm wrong = about how=20 much damage there might be, it will get expensive, but shouldn't be = life=20 threatening. 
 
Many of you = have a lot=20 more experience with these engines than I do.  Does this sound = like a=20 reasonable plan?
 
Thanks,
Rusty (late = for the=20 airport as always)
 
 
 
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