X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [207.46.163.206] (HELO na01-bl2-obe.outbound.protection.outlook.com) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTPS id 6640571 for lml@lancaironline.net; Mon, 16 Dec 2013 09:34:37 -0500 Received-SPF: pass receiver=logan.com; client-ip=207.46.163.206; envelope-from=rpastusek@htii.com Received: from BY2PR07MB550.namprd07.prod.outlook.com (10.141.217.145) by BY2PR07MB549.namprd07.prod.outlook.com (10.141.217.140) with Microsoft SMTP Server (TLS) id 15.0.842.7; Mon, 16 Dec 2013 14:33:32 +0000 Received: from BY2PR07MB550.namprd07.prod.outlook.com ([10.141.217.145]) by BY2PR07MB550.namprd07.prod.outlook.com ([10.141.217.145]) with mapi id 15.00.0842.003; Mon, 16 Dec 2013 14:33:32 +0000 From: Robert R Pastusek To: Lancair Mailing List Subject: RE: [LML] Paint Cracks Thread-Topic: [LML] Paint Cracks Thread-Index: AQHO+l4dGebM1gLqY0e6KocW9I5HY5pW1UHg Date: Mon, 16 Dec 2013 14:33:31 +0000 Message-ID: <37cf2749816a43c19d5adb49e66d5d99@BY2PR07MB550.namprd07.prod.outlook.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [108.28.164.93] x-forefront-prvs: 0062BDD52C x-forefront-antispam-report: SFV:NSPM;SFS:(10019001)(199002)(189002)(52314003)(24454002)(74316001)(19300405004)(31966008)(83322001)(19580405001)(85852003)(77982001)(59766001)(74662001)(54356001)(74366001)(80022001)(56776001)(53806001)(19580395003)(85306002)(33646001)(50986001)(47976001)(15975445006)(47736001)(49866001)(15202345003)(4396001)(54316002)(81816001)(81686001)(16236675002)(76786001)(46102001)(74876001)(51856001)(2656002)(87266001)(74706001)(65816001)(81342001)(83072002)(87936001)(74502001)(81542001)(66066001)(76796001)(76576001)(80976001)(69226001)(76482001)(47446002)(90146001)(63696002)(56816005)(79102001)(24736002);DIR:OUT;SFP:1102;SCL:1;SRVR:BY2PR07MB549;H:BY2PR07MB550.namprd07.prod.outlook.com;CLIP:108.28.164.93;FPR:;RD:InfoNoRecords;A:1;MX:3;LANG:en; Content-Type: multipart/alternative; boundary="_000_37cf2749816a43c19d5adb49e66d5d99BY2PR07MB550namprd07pro_" MIME-Version: 1.0 X-OriginatorOrg: htii.com --_000_37cf2749816a43c19d5adb49e66d5d99BY2PR07MB550namprd07pro_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Justin Wrote: I recently had my ESP painted and there are already significant cracks show= ing in the paint around the door frame corners and hinges. I was told that = the flexibility of modern urethane paints would prevent this. How common is= this for the pressurized aircraft? Justin, I went to great pains to prevent this while building my IV-P...bedded every= through-bolt in flox/epoxy, and covered every through-bolt around the door= and over each "chicken plate" where the pressure bulkheads attach to the f= uselage (except two that I missed...but that's another story). Anyway, N437= RP looked perfect when we first flew it...and for about a year. Then I star= ted noticing very slight "dimples" where the screw heads were located. No c= racks or breaks, but the surface was being pulled inward very slightly...I = presume by flexing during pressurization. To be sure, these are very diffic= ult to see; I'd likely need to point them out with a light or specific sun = angle for you to see them at all, but they are noticeable to a discerning b= uilder... At almost 6 years/1200 hours now, I am starting to develop slight cracks in= the paint around the door latches. Nothing longer than =BC," but every lat= ch attachment as at least one. They are more noticeable than the dimples. I= am sure these are not structural defects, and I took one of the latches of= f the fuselage to look at the flox pad it's mounted on...just to be sure. I= t's absolutely solid; no cracks or visible defects. My opinion is that the = fuselage/door undergo a lot more flexing/expansion than you'd imagine durin= g pressurization cycles; that some deformation/cracking at the stress point= s is inevitable. ...one reason to be sure the cabin over-pressure relief wo= rks as intended... J I'd be interested in the comments of others, but I'm not sure how/if these = can be completely eliminated. Bob Pastusek --_000_37cf2749816a43c19d5adb49e66d5d99BY2PR07MB550namprd07pro_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Justin Wrote:

 

I recently had my ESP painted and there are already = significant cracks showing in the paint around the door frame corners and h= inges. I was told that the flexibility of modern urethane paints would prev= ent this. How common is this for the pressurized aircraft? 

Justin,

I went to great pains to prevent this while building my IV-P…bedd= ed every through-bolt in flox/epoxy, and covered every through-bolt ar= ound the door and over each “chicken plate” where the pressure = bulkheads attach to the fuselage (except two that I missed…but that&#= 8217;s another story). Anyway, N437RP looked perfect when we first flew it…and for about a year. Then I started noticing very = slight “dimples” where the screw heads were located. No cracks = or breaks, but the surface was being pulled inward very slightly…I pr= esume by flexing during pressurization. To be sure, these are very difficult to see; I’d likely need to point them out with a = light or specific sun angle for you to see them at all, but they are notice= able to a discerning builder…

At almost 6 years/1200 hours now, I am starting to develop slight crack= s in the paint around the door latches. Nothing longer than =BC,” but every latch attachment as at least one. They are more noticeable than = the dimples. I am sure these are not structural defects, and I took one of = the latches off the fuselage to look at the flox pad it’s mounted on…just to = be sure. It’s absolutely solid; no cracks or visible defects. My opin= ion is that the fuselage/door undergo a lot more flexing/expansion than you= ’d imagine during pressurization cycles; that some deformation/cracki= ng at the stress points is inevitable. …one reason to be sure the cabin= over-pressure relief works as intended… J

I’d be interested in the comments of others, but I’m not su= re how/if these can be completely eliminated.

Bob Pastusek

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