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 4.3.5) with ESMTP id 1020327 for flyrotary@lancaironline.net; Fri, 24 Jun 2005 11:02:54 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-065-188-083-049.carolina.res.rr.com [65.188.83.49]) by ms-smtp-04-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j5OF24L5010995 for ; Fri, 24 Jun 2005 11:02:06 -0400 (EDT) Message-ID: <000601c578cd$b0374c50$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" Subject: Engine Rebuild - Coolant Leak Cause Date: Fri, 24 Jun 2005 11:02:06 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0003_01C578AC.28E08D00" 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_0003_01C578AC.28E08D00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Those of you who look at the Real World Solutions web site and their = latest photos may recall seeing a photo titled "Congratulations, it's a = boy" which shows coolant squirting into the air from my overflow tank. = Photo taken at Charlie's fly in. That was pretty good evidence of a = coolant leak between combustion chamber and coolant galleys and = supported by the fact that I had notice my coolant pressure increasing = on the flight to Charlies by approx 11/2 psi per hour of flight. It = started at a normal 10 psi and had increased to18 psi by the end of the = flight. =20 Well, by the time I had flown another two hours to Louisiana in and out = of rain showers, etc, back-tracking, I finally made it to my = destination. There I found that the number 1 (front) rotor would shoot = coolant out of the removed spark plug hole like old faithful when I = pulled the prop through. Clearly, had to fix the problem. Upon = opening up the engine I found two things 1. One of the triangular pieces of the apex seal was missing - I first = though it had fallen out on disassembly in my brother-in-law's garage, = but concerted search failed to locate it.=20 2. There were two "hot" spots (metal discolored to blue) on the front = rotor side housings opposite each other. One about the size of a half = dollar coin was on the side of the missing piece of the apex seal. the = second spot on the opposite housing at the same location was smaller = about the size of a quarter. It was clear looking at the "O" rings = that the heat had compromised their integrity. The appearance of the = "O" rings at that spot was as if they had shrunk in diameter. Elsewhere = the "O" rings were slightly proud of the surface of the side housing = indicating good sealing. Someone on the list suggested that the missing piece of the apex seal = might have gotten wedge at the end of the rotor and caused the problem. = At first, I was inclined to dismiss that hypothesis but failure to find = any other explanation leads me to the following conclusion. At this point, it appears that one of the triangular pieces of the apex = seal (could not find it anywhere) left its proper position (undoubtedly = during my assembly) and got lodged at the end (apex) of one of the = rotors. May have been held their by some combination of the corner and = side seal. In any case, it appears that one area of the rotor housing = was slightly narrower than the rest (some area has to be {:>)). Every = time that rotor with the wedged piece of apex seal passed that area it = created tremendous friction and heated the side housing hot enough for = the blue discoloration. The large Hot spot was on the side of the rotor = that the piece of apex seal would normally have been. I think the = smaller Hot spot on the opposite side housing was due to the rotor being = pushed to that side by the wedged piece on the opposite side of the = rotor. So the brunt of the heat occurred where the wedged piece was = rubbing the side wall - but, at that same spot in rotation, the seal = piece forced the opposite side of the rotor into the opposite side wall = creating a smaller hot spot - but still sufficient to overheat the "O" = ring. The wedged piece probably accounts for the initial tightness of the = engine and after two hours of running it had either disintegrated or = dropped out of the housing causing the engine to loosen up. Of course, = by that time the damage to the "O" rings had been done and the results = was the slowly increasing in my coolant pressure and of course the = resulting "Congratulations, it's a boy" photo. The main point is that several folks (including Bruce T) expressed = concern when I reported the initial tightness after reassemble from my = apex seal failure on way to Sun & Fun. However, I was in a hurry to get = my aircraft off that derelict airfield and talked my self into the = notion that I had just rebuild a really "tight" engine. Clearly, I paid = for that by having to open up and correct the situation. This time = there was no tightness and the compression was even better (guess the = missing apex seal piece could account for less compression as well). Fortunately, having friends like Laura and Tracy Crook really helps. = Laura was practically reading my mind in shipping the parts I needed to = get the engine back together. The longest time line was simply the time = required to get the parts I needed. No local source within 60 miles was = found. As always, I aim to share my experience in hopes it will preclude = someone from making the same mistakes I made. Between the brake failure/fire and the engine rebuild in no-rotary land = during the heat and humidity of a Louisiana summer, its been one long = month - but finally home and glad to be doing "Honey Dos" Best Regards Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ------=_NextPart_000_0003_01C578AC.28E08D00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

 

Those of you who look at the Real = World Solutions=20 web site and their latest photos may recall seeing a photo titled=20 "Congratulations, it's a boy" which shows coolant squirting into the air = from my=20 overflow tank.  Photo taken at Charlie's fly in.  That was = pretty good=20 evidence of a coolant leak between combustion chamber and coolant = galleys and=20 supported by the fact that I had notice my coolant pressure increasing = on the=20 flight to Charlies by approx 11/2 psi per hour of flight. It started at = a normal=20 10 psi and had increased to18 psi by the end of the flight.  =

Well, by the time I had flown another = two hours to=20 Louisiana in and out of rain showers, etc, back-tracking, I finally made = it to=20 my destination.  There I found that the number 1 (front) rotor = would shoot=20 coolant out of the removed spark plug hole like old faithful when I = pulled the=20 prop through.  Clearly, had to fix the problem.    Upon = opening=20 up the engine I found two things

1.  One of the triangular pieces = of the apex=20 seal was missing - I first though it had fallen out on disassembly in my = brother-in-law's garage,  but concerted search failed to locate it. =

2.  There  were two "hot" = spots (metal=20 discolored to blue) on the front rotor side housings opposite each = other. =20 One about the size of a half dollar coin was on the side of the = missing=20 piece of the apex seal. the second spot on the opposite housing at the = same=20 location was smaller about the size of a quarter.   It was = clear=20 looking at the "O" rings that the heat had compromised their = integrity. =20 The appearance of the "O" rings at that spot was as if they had shrunk = in=20 diameter.  Elsewhere the "O" rings were slightly proud of the = surface of=20 the side housing indicating good sealing.

Someone on the list suggested that the = missing=20 piece of the apex seal might have gotten wedge at the end of the rotor = and=20 caused the problem.  At first, I was inclined to dismiss that = hypothesis=20 but failure to find any other explanation leads me to the following=20 conclusion.

At this point, it appears that = one of the=20 triangular pieces of the apex seal (could not find it anywhere) left its = proper=20 position (undoubtedly during my assembly) and got lodged at the end = (apex) of=20 one of the rotors. May have been held their by some combination of the = corner=20 and side seal. In any case, it appears that one area of the rotor = housing was=20 slightly narrower than the rest (some area has to be {:>)). Every = time that=20 rotor with the wedged piece of apex seal passed that area it created = tremendous=20 friction and heated the side housing hot enough for the blue = discoloration. The=20 large Hot spot was on the side of the rotor that the piece of apex seal = would=20 normally have been. I think the smaller Hot spot on the opposite side = housing=20 was due to the rotor being pushed to that side by the wedged piece on = the=20 opposite side of the rotor. So the brunt of the heat occurred where the = wedged=20 piece was rubbing the side wall =96 but, at that same spot in = rotation,=20  the seal piece forced the opposite side of the rotor into the = opposite side wall creating a smaller hot spot =96 but still sufficient = to=20 overheat the "O" ring.

The wedged piece = probably accounts=20 for the initial tightness of the engine and after two hours of running = it had=20 either disintegrated or dropped out of the housing causing the engine to = loosen=20 up. Of course, by that time the damage to the "O" rings had been done = and the=20 results was the slowly increasing in my coolant pressure and of course = the=20 resulting "Congratulations, it=92s a boy" photo.

The main point is that several folks = (including=20 Bruce T) expressed concern when I reported the initial tightness after=20 reassemble from my apex seal failure on way to Sun & Fun.  = However, I=20 was in a hurry to get my aircraft off that derelict airfield and talked = my self=20 into the notion that I had just rebuild a really "tight" engine.  = Clearly,=20 I paid for that by having to open up and correct the situation.  = This time=20 there was no tightness and the compression was even better (guess the = missing=20 apex seal piece could account for less compression as well).

Fortunately, having friends like Laura = and Tracy=20 Crook really helps.  Laura was practically reading my mind in = shipping the=20 parts I needed to get the engine back together.  The longest time = line was=20 simply the time required to get the parts I needed.  No local = source within=20 60 miles was found.

As always, I aim to share my = experience in hopes=20 it will preclude someone from making the same mistakes I = made.

Between the brake failure/fire and the = engine=20 rebuild in no-rotary land during the heat and humidity of a Louisiana = summer,=20 its been one long month - but finally home and glad to be doing "Honey=20 Dos"

Best Regards

Ed

Ed Anderson
Rv-6A N494BW Rotary = Powered
Matthews,=20 NC
eanderson@carolina.rr.com
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