X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao06.cox.net ([68.230.241.33] verified) by logan.com (CommuniGate Pro SMTP 5.1c.2) with ESMTP id 1332647 for flyrotary@lancaironline.net; Tue, 01 Aug 2006 20:49:51 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.33; envelope-from=ALVentures@cox.net Received: from BigAl ([72.192.132.90]) by fed1rmmtao06.cox.net (InterMail vM.6.01.06.01 201-2131-130-101-20060113) with ESMTP id <20060802004902.GPOH6235.fed1rmmtao06.cox.net@BigAl> for ; Tue, 1 Aug 2006 20:49:02 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Auto Fuel - composite tanks Date: Tue, 1 Aug 2006 17:49:07 -0700 Message-ID: <000001c6b5cd$75e4f460$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C6B592.C9861C60" 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 V6.00.2900.2869 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C6B592.C9861C60 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =20 If you read the archives from canard builders you will find it's = extremely common to have such pinhole leaks. If I had to guess, I'd say 50% have = this problem. Regardless of type of fuel I agree that could well be that the leak in the bottom strake inner skin = has been there and has nothing to do with the type of fuel. I had leak = tested with air after strake closure, and it held about an 8 =96 10=94 head of = water pressure for days. =20 If you had any mushiness near leaks, then I'd be concerned. I tested non-compatible epoxy and it just gradually got mushy. What I have now is a roughly oval area about 6=94 by 4=94 where the = weave of the glass cloth is showing through the paint finish, and it feels/looks like there maybe some dis-bonding of the outer skin from the foam. My guess = is that somewhere in that area there is a pinhole leak in the inner skin, = and the fuel has permeated the foam. There is no fuel leak on the outside. Because of the roughness/weave showing, and the dis-bonding, it seems = clear that the fuel (or something) is doing something to the epoxy. It was my understanding that fuel (avgas, I suppose) would not permeate the closed cell PVC foam, and not effect the epoxy. I drained tank, then drill 1/16" hole at leak location. Hole only goes = part way into tank wall. Fuel came burbling out. I then used syringe with no needle to inject epoxy. Totally solved problem, no leaks for years now. Do you also have a foam core sandwich tank wall? How did you decide = where to drill the outer skin? What epoxy did you use; I=92d think the = presence of fuel would mess up the epoxy before it cured? Leaks take a long time to show on surface, fuel has to migrate from = interior hole to exterior hole. That also makes it tough to find leak source. I=92ve drained the fuel on that side, and for now I=92m leaving it as is = since we are trying to get first flight done Friday/Saturday. I=92ll probably = put some avgas in on that side for balance, and deal with the apparent leak later. Thanks, Al =20 =20 =20 On Mon, 31 Jul 2006 10:14:58 -0700 "Al Gietzen" = writes: Not sure where to go with this because there are only a few here with = epoxy fuel tanks, and on the Velocity list very few interested in the use of mogas. I=92m suspecting fuel compatibility isses. =20 I first put fuel in the tanks nearly 2 years ago and used Chevron = regular. Everything was fine. When I moved the plane to the airport 3 months ago (tanks empty) I filled with Exxon-Mobile. Four troubling things have = come up in the past few weeks.=20 =20 1. I have Vance Atkinson site gauge that has a white plastic back = plate for easier reading of the fuel level. The small hole through the backing = has been swelling shut so the sight gauge no longer works. I contacted Vance = who said that there are hundreds of these gauges in EZs using mogas without problems, but he has had 3 incidents like mine in the last three months. = 2. A couple of weeks ago there was suddenly a pinhole leak in one of = the gear well enclosures. These enclosures are part of the fuel tank wall, = and are parts that come with the Velocity kit. These are also made and = coated with EZ-poxy.=20 3. Looking in through the filler cap I see reddish-purple splotches = and streaks on those gear leg enclosures. Poking and scratching with some safety wire on a stick does not indicate any softness of the surface.=20 4. Yesterday, under the leading edges of one of the strakes, I noted = an area with some slight surface irregularity. Pushing on it suggests some sponginess. This is =BD=94 foam core material, and indicates the = possibility of a pinhole leak in the inner skin, and fuel softening the PVC foam. PVC = foam is supposed to be unaffected by fuel.=20 =20 My tanks (strakes) were made and coated with EZ-poxy back in 1998. At = the time I polled EZ flyers about there experience, and talked to reps of various epoxy manufacturers about auto fuel compatibility. All the = evidence said go with the EZ-poxy. =20 Any others with composite tanks having any trouble? Anybody using Exxon-mobile fuel? Know of any new additives that are an issue? =20 I=92m thinking I should drain this fuel ASAP, but then what? Other = brand? That expensive Avgas? Regardless I may be faced with cutting open a = strake at some point, but right now we are trying to get first flight done this coming weekend. =20 =20 =20 -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design = info: http://www.maddyhome.com/canardpages/pages/alwick/index.html ------=_NextPart_000_0001_01C6B592.C9861C60 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

 

If you read the archives from canard builders = you will find it's extremely common to have such pinhole leaks. If I had to = guess, I'd say 50% have this problem. Regardless of type of fuel

I agree that could well be that = the leak in the bottom strake inner skin has been there and has nothing to do = with the type of fuel.=A0 I had leak tested with air after strake closure, and it = held about an 8 – 10” head of water pressure for = days.

=A0

If you had any mushiness near leaks, then I'd = be concerned. I tested non-compatible epoxy and it just gradually got = mushy.

What I have now is a roughly oval = area about 6” by 4” where the weave of the glass cloth is showing through the paint finish, and it feels/looks like there maybe some = dis-bonding of the outer skin from the foam. My guess is that somewhere in that area = there is a pinhole leak in the inner skin, and the fuel has permeated the = foam.=A0 There is no fuel leak on the outside.=A0 Because of the roughness/weave = showing, and the dis-bonding, it seems clear that the fuel (or something) is doing = something to the epoxy.=A0 It was my understanding that fuel (avgas, I suppose) = would not permeate the closed cell PVC foam, and not effect the = epoxy.

I drained tank, then drill 1/16" hole at = leak location. Hole only goes part way into tank wall. Fuel came burbling = out. I then used syringe with no needle to inject epoxy. Totally solved = problem, no leaks for years now.

Do you also have a foam core sandwich = tank wall? =A0How did you decide where to drill the outer skin?  What epoxy = did you use; I’d think the presence of fuel would mess up the epoxy before = it cured?

Leaks take a long time to show on surface, = fuel has to migrate from interior hole to exterior hole. That also makes it tough to = find leak source.

I’ve drained the fuel on that = side, and for now I’m leaving it as is since we are trying to get first = flight done Friday/Saturday. =A0I’ll probably put some avgas in on that side = for balance, and deal with the apparent leak later.

Thanks,

Al

=A0

 

 

On Mon, 31 Jul 2006 10:14:58 = -0700 "Al Gietzen" <ALVentures@cox.net> writes:

Not sure where to go with = this because there are only a few here with epoxy fuel tanks, and on the = Velocity list very few interested in the use of mogas.  I’m suspecting = fuel compatibility isses.

 

I first put fuel in the = tanks nearly 2 years ago and used Chevron regular. Everything was fine.  = When I moved the plane to the airport 3 months ago (tanks empty) I filled with Exxon-Mobile.  Four troubling things have come up in the past few = weeks.

 

1.     I have Vance Atkinson site gauge that has a = white plastic back plate for easier reading of the fuel level. The small hole = through the backing has been swelling shut so the sight gauge no longer works. I contacted Vance who said that there are hundreds of these gauges in EZs = using mogas without problems, but he has had 3 incidents like mine in the last = three months.

2.     A couple of weeks ago there was suddenly a = pinhole leak in one of the gear well enclosures.  These enclosures are part = of the fuel tank wall, and are parts that come with the Velocity kit. =  These are also made and coated with EZ-poxy.

3.     Looking in through the filler cap I see reddish-purple splotches and streaks on those gear leg enclosures.  = Poking and scratching with some safety wire on a stick does not indicate any = softness of the surface.

4.     Yesterday, under the leading edges of one of = the strakes, I noted an area with some slight surface irregularity.  = Pushing on it suggests some sponginess.  This is =BD” foam core = material, and indicates the possibility of a pinhole leak in the inner skin, and fuel softening the PVC foam.  PVC foam is supposed to be unaffected by = fuel.

 

My tanks (strakes) were = made and coated with EZ-poxy back in 1998.  At the time I polled EZ flyers = about there experience, and talked to reps of various epoxy manufacturers = about auto fuel compatibility.  All the evidence said go with the = EZ-poxy.

 

Any others with composite = tanks having any trouble?  Anybody using Exxon-mobile fuel?  Know of = any new additives that are an issue?

 

I’m thinking I = should drain this fuel ASAP, but then what?  Other brand?  That expensive Avgas?  Regardless I may be faced with cutting open a strake at = some point, but right now we are trying to get first flight done this coming weekend.

 

 

 


-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru = 2.5
N9032U 200+ hours on engine/airframe from Portland, = Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design = info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html

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