Return-Path: Received: from fed1rmmtao09.cox.net ([68.230.241.30] verified) by logan.com (CommuniGate Pro SMTP 4.2.1) with ESMTP id 401398 for flyrotary@lancaironline.net; Tue, 07 Sep 2004 19:18:24 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.30; envelope-from=ALVentures@cox.net Received: from BigAl ([68.107.116.221]) by fed1rmmtao09.cox.net (InterMail vM.6.01.03.02.01 201-2131-111-104-103-20040709) with ESMTP id <20040907231752.FTLA16651.fed1rmmtao09.cox.net@BigAl> for ; Tue, 7 Sep 2004 19:17:52 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] high oil pressure and coolers Date: Tue, 7 Sep 2004 16:17:55 -0700 Message-ID: <000001c49530$e7c9fe00$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C494F6.3B6B2600" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C494F6.3B6B2600 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Me thinks thou dost worry too much. =20 First, he still says he wouldn't run over 210F. I was of course hoping = that he's say it was OK to run more. =20 I would not suggest running routinely over about 210, but I'd see no = great worries for short durations over that. It is not the lubrication or the lubricant that we are concerned about - it's the side seal o-rings. = Running over 210-220 consistently will speed loss of seal. At least that's the consensus that I've pulled together. =20 Next, I was asking about how the oil pressure regulator worked, and got = an education. While this may not be news to some of you, others will find = it as disturbing as I do. The engine has two oil regulators. In my case, = the normal regulator is set at about 75 psi, and is at the inlet of the oil = to the engine. The other regulator is in the front cover, to regulate oil outlet pressure, and is fixed at 157 psi!!! This is to allow for restriction in the oil coolers and long lines. He said you'll see this = when cold, and likely during that first climbout, but he didn't believe it = would stay that high all the time. He did think it would always be over 100 = psi though. =20 The 'regulator' in the front cover is not so much regulator as it is emergency bypass at the pump outlet. This means that the pressure will never go above 157 psi at the outlet because it is bypassed back to the = pan. I don't know about your evaporator coolers, but it is very unlikely that = you would ever see more than 10-20 psi drop in the rest of your loop, = including the filter. And I don't think you are ever going to start your takeoff = roll when the oil temp is less than about 140F, at which point it is very = fluid - unless you are using 60 weight gear oil :-).=20 =20 I have 100 psi regulator for the "normal" regulator, -10 lines with = cooler and filters (dual in parallel) and I am not very concerned. (hum-m-m; = does that help any?) I'd say with your 75 psi regulator you can relax. Just don't start up on a 20F day and immediately rev to 6000. =20 >>>Didn't a rotary airplane have two (count 'em) engine fires because of burst aftermarket oil coolers. If memory serves the owners wife made him sell the rotary and install a Lycoming. <<< =20 This is a guy that had three coolers in series, two of which where in = the nose (engine in back) with long runs of -6 line and many fittings. Also = had a 100 psi regulator. You can bet that pressure to the first cooler; the = one that ruptured twice, was always at the relief pressure of 157 psi. Add = to that some unsupported heavy flex line to the connector on the cooler = tank (can you say "fatigue failure"), and you have a prescription for a bad = day. I had cautioned him twice about the poor flow path and high pressures; = but to no avail. He is just completing the installaton of a turbocharged = IO360 that he rebuilt himself. He had it run up on a test stand for break-in = and it runs well, and he expects to be flying soon. =20 =20 Al ------=_NextPart_000_0001_01C494F6.3B6B2600 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

Me thinks thou dost worry too = much.

 

First, he still says he = wouldn't run over 210F.  I was of course hoping that he's say it was OK to run more. 

I would not suggest running = routinely over about 210, but I’d see no great worries for short durations = over that.  It is not the lubrication or the lubricant that we are = concerned about – it’s the side seal o-rings.  Running over = 210-220 consistently will speed loss of seal.  At least that’s the = consensus that I’ve pulled together.

 

Next, I was asking about = how the oil pressure regulator worked, and got an education.  While this may = not be news to some of you, others will find it as disturbing as I do.  = The engine has two oil regulators.  In my case, the normal regulator is = set at about 75 psi, and is at the inlet of the oil to the engine.  The = other regulator is in the front cover, to regulate oil outlet pressure, and is = fixed at 157 psi!!!  This is to allow for restriction in the oil coolers = and long lines.  He said you'll see this when cold, and likely during = that first climbout, but he didn't believe it would stay that high all = the time.  He did think it would always be over 100 psi = though.

 

The ‘regulator’ in = the front cover is not so much regulator as it is emergency bypass at the pump = outlet.  This means that the pressure will never go above 157 psi at the outlet = because it is bypassed back to the pan.  I don’t know about your = evaporator coolers, but it is very unlikely that you would ever see more than 10-20 = psi drop in the rest of your loop, including the filter.  And I = don’t think you are ever going to start your takeoff roll when the oil temp is = less than about 140F, at which point it is very fluid – unless you are = using 60 weight gear oil J.

 

 I have 100 psi regulator = for the “normal” regulator, -10 lines with cooler and filters (dual in parallel) and I am = not very concerned. (hum-m-m; does that help any?)  I’d say with your = 75 psi regulator you can relax.  Just don’t start up on a 20F day = and immediately rev to 6000.

 

>>>Didn't a rotary = airplane have two (count 'em) engine fires because of burst aftermarket oil coolers. If memory serves the owners wife made him sell the rotary = and install a Lycoming. <<<= ;

 

This is a guy that had three = coolers in series, two of which where in the nose (engine in back) with long runs = of -6 line and many fittings. Also had a 100 psi regulator.  You can bet = that pressure to the first cooler; the one that ruptured twice, was always at = the relief pressure of 157 psi.  Add to that some unsupported heavy = flex line to the connector on the cooler tank (can you say “fatigue = failure”), and you have a prescription for a bad day.  I had cautioned him = twice about the poor flow path and high pressures; but to no avail.  He = is just completing the installaton of a turbocharged IO360 that he rebuilt = himself.  He had it run up on a test stand for break-in and it runs well, and he = expects to be flying soon. 

 

Al

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