X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 12 Jul 2010 09:41:14 -0400 Message-ID: X-Original-Return-Path: Received: from DB3EHSOBE004.bigfish.com ([213.199.154.142] verified) by logan.com (CommuniGate Pro SMTP 5.3.8) with ESMTPS id 4388389 for lml@lancaironline.net; Sat, 10 Jul 2010 23:41:13 -0400 Received-SPF: pass receiver=logan.com; client-ip=213.199.154.142; envelope-from=rpastusek@htii.com Received: from mail37-db3-R.bigfish.com (10.3.81.252) by DB3EHSOBE004.bigfish.com (10.3.84.24) with Microsoft SMTP Server id 8.1.436.0; Sun, 11 Jul 2010 03:40:35 +0000 Received: from mail37-db3 (localhost.localdomain [127.0.0.1]) by mail37-db3-R.bigfish.com (Postfix) with ESMTP id CC0CC19201EE for ; Sun, 11 Jul 2010 03:40:35 +0000 (UTC) X-SpamScore: -4 X-BigFish: VPS-4(zzace9izz1202hzz186Mz2fh2a8h) Received: from mail37-db3 (localhost.localdomain [127.0.0.1]) by mail37-db3 (MessageSwitch) id 1278819630824416_18474; Sun, 11 Jul 2010 03:40:30 +0000 (UTC) Received: from DB3EHSMHS001.bigfish.com (unknown [10.3.81.253]) by mail37-db3.bigfish.com (Postfix) with ESMTP id 97BF816B0062 for ; Sun, 11 Jul 2010 03:40:03 +0000 (UTC) Received: from va3diahub022.RED001.local (65.55.171.153) by DB3EHSMHS001.bigfish.com (10.3.87.101) with Microsoft SMTP Server (TLS) id 14.0.482.44; Sun, 11 Jul 2010 03:40:03 +0000 Received: from VA3DIAXVS171.RED001.local ([172.18.2.196]) by va3diahub022.RED001.local ([10.32.21.22]) with mapi; Sat, 10 Jul 2010 20:40:03 -0700 From: Robert R Pastusek X-Original-To: Lancair Mailing List X-Original-Date: Sat, 10 Jul 2010 20:39:08 -0700 Subject: Door Window Failure-Lancair IV-P Thread-Topic: Door Window Failure-Lancair IV-P Thread-Index: Acsgn0hyjcvyGQgcSsyWrgHXbQSNgAAAydjA X-Original-Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-cr-hashedpuzzle: VPU= B+Gu C/WA DZwN FJhn FlP8 GfF9 Go9T G8IO HQvf IMlX Imap JnVx KKzN KLpO L7/M;1;bABtAGwAQABsAGEAbgBjAGEAaQByAG8AbgBsAGkAbgBlAC4AbgBlAHQA;Sosha1_v1;7;{0BDAE788-9BB6-4185-B7AC-6A01E43E57AD};cgBwAGEAcwB0AHUAcwBlAGsAQABoAHQAaQBpAC4AYwBvAG0A;Sun, 11 Jul 2010 03:39:08 GMT;RABvAG8AcgAgAFcAaQBuAGQAbwB3ACAARgBhAGkAbAB1AHIAZQAtAEwAYQBuAGMAYQBpAHIAIABJAFYALQBQAA== x-cr-puzzleid: {0BDAE788-9BB6-4185-B7AC-6A01E43E57AD} acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_E374BE0180357344BBD396A27A0527F60F18F6C0VA3DIAXVS171RED_" MIME-Version: 1.0 X-Reverse-DNS: smtp801.microsoftonline.com X-Original-Return-Path: rpastusek@htii.com --_000_E374BE0180357344BBD396A27A0527F60F18F6C0VA3DIAXVS171RED_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Gentlemen, After much exchange of ideas and techniques with several of you, I finally = cut into my cabin door today to replace a cracked window. I discovered this= crack-only visible by looking at an angle into the sandwich between the in= ner and outer skins in the upper back corner-during pre-flight. The crack d= id not extend into the transparent part of the window. This was one of the = early "fast build" doors from Lancair; purchased in 2004-2005. I will post = a detailed report when I'm done, but thought you'd be interested in what I = found today...I was surprised. As this fault was observed directly opposite a door latch, I assumed it res= ulted from the holes drilled through the Plexi to accommodate the latch. As= the door/window was still intact (not blown out), I was careful to grind a= way carbon from the outside to free the window without further damage so we= could confirm this. As I removed the carbon, I exposed a 4" crack starting= about an inch below the latch and extending toward the top of the door and= around the corner radius. The crack was about =BC" "under" the carbon skin= , and had not progressed to the edge of the Plexi at either end. It did not= originate at the bolt holes, but was generally parallel to the edge of the= Plexi and about =BD" farther from the edge than the bolt holes. The crack = appeared to be caused by forceful flexing of the Plexi parallel to its edge= . I am not a structural engineer, but observed two possibilities. First hypothesis: the latch exerts a twisting moment on the door frame whe= n closed and the door is pressurized. Possible, but I checked the latch ali= gnment and function carefully during initial installation, and all of them = are aligned the same, and work very easily...no binding and no stress upon = opening or closing. They also engage fully, and only very slightly "pull" o= n the door frame when going over-center. No other latches showed any damage= or stress in the area, and one of the forward latches is also bolted with = holes drilled through the Plexi. The process of pressurizing is a gradual i= ncrease in force on the door/window, allowing them to conform-within their = stress limits. This concept seems to work for all other areas around the do= or/window. Second hypothesis. The FB door re-oriented the lift strut location so that= its door attach point is just above the"offending" latch location, and it= s mounted to the door stiffener. On at least two known occasions, other peo= ple have opened the canopy door in the wind and allowed it to extend the li= ft strut forcibly against the lift strut internal stop. This would cause a = sudden twisting of the door frame in the location of the crack. Although bo= th violent door openings occurred some time ago, I believe this to be the c= ause of the failure--subject to further review/ideas/comments from you. A couple of related observations. The door was well constructed in the area= s I opened. I found no voids or weak areas. Holes in the Plexi for through-= bolts had been drilled to approximately =BD", filled with Hysol and redrill= ed. All four of them were intact, and these "spacers" quite forcefully held= the inner and outer skins together. The window had been bedded against the= outer skin with Hysol, and bedded with micro around the edges. The window = was well attached to the door skins, although it could be separated with a = thin putty knife. The bond appears to be mechanical-the Hysol adheres by co= nforming very closely to the rough surface without making a chemical or adh= esive attachment. More to follow as I have data... Bill Harrelson and I took a lot of pictures, and I'll take more as we compl= ete this job. I'll write up the details for posting on the LML and LOBO web= sites for those interested. I'd like to extend a special thanks to Laurie = Fitzgerald (Australia), Brent Regan and Brad Simmons for their exceptional = advice, pictures, information-and encouragement. As with most things done o= n this airplane, I'm combining their excellent recommendations to hopefully= make a long-lasting and reliable fix. See you at Oshkosh! Bob --_000_E374BE0180357344BBD396A27A0527F60F18F6C0VA3DIAXVS171RED_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Gentlemen,

 

After much exchange of ideas and techniques with several of = you, I finally cut into my cabin door today to replace a cracked window. I discovered this crack—only visible by looking at an angle into the sa= ndwich between the inner and outer skins in the upper back corner—during pre= -flight. The crack did not extend into the transparent part of the window. This was = one of the early “fast build” doors from Lancair; purchased in 2004-2005. I will post a detailed report when I’m done, but thought y= ou’d be interested in what I found today…I was surprised.

 

As this fault was observed directly opposite a door latch, I assumed it resulted from the holes drilled through the Plexi to accommodate= the latch. As the door/window was still intact (not blown out), I was careful t= o grind away carbon from the outside to free the window without further damag= e so we could confirm this. As I removed the carbon, I exposed a 4” crack = starting about an inch below the latch and extending toward the top of the door and around the corner radius. The crack was about =BC” “under”= ; the carbon skin, and had not progressed to the edge of the Plexi at either end.= It did not originate at the bolt holes, but was generally parallel to the edge= of the Plexi and about =BD” farther from the edge than the bolt holes. T= he crack appeared to be caused by forceful flexing of the Plexi parallel to its edge= .

 

I am not a structural engineer, but observed two possibiliti= es.

 

First hypothesis: =A0the latch exerts a twisting moment on t= he door frame when closed and the door is pressurized. Possible, but I checked= the latch alignment and function carefully during initial installation, and all= of them are aligned the same, and work very easily…no binding and no str= ess upon opening or closing. They also engage fully, and only very slightly “p= ull” on the door frame when going over-center. No other latches showed any damag= e or stress in the area, and one of the forward latches is also bolted with hole= s drilled through the Plexi. The process of pressurizing is a gradual increas= e in force on the door/window, allowing them to conform—within their stres= s limits. This concept seems to work for all other areas around the door/wind= ow.

 

Second hypothesis. The FB=A0 door re-oriented the lift strut location so that its door attach point is just above the”offending= 221; =A0latch location, and its mounted to the door stiffener. On at least two k= nown occasions, other people have opened the canopy door in the wind and allowed= it to extend the lift strut forcibly against the lift strut internal stop. Thi= s would cause a sudden twisting of the door frame in the location of the crack. Alt= hough both violent door openings occurred some time ago, I believe this to be the= cause of the failure--subject to further review/ideas/comments from you.

 

A couple of related observations. The door was well construc= ted in the areas I opened. I found no voids or weak areas. Holes in the Plexi f= or through-bolts had been drilled to approximately =BD”, filled with Hysol and redrill= ed. All four of them were intact, and these “spacers” quite forcefu= lly held the inner and outer skins together. The window had been bedded against= the outer skin with Hysol, and bedded with micro around the edges. The window w= as well attached to the door skins, although it could be separated with a thin putty knife. The bond appears to be mechanical—the Hysol adheres by conforming very closely to the rough surface without making a chemical or adhesive attachment. More to follow as I have data…=

 

Bill Harrelson and I took a lot of pictures, and I’ll = take more as we complete this job. I’ll write up the details for posting o= n the LML and LOBO web sites for those interested. I’d like to extend a= special thanks to Laurie Fitzgerald (Australia), Brent Regan and Brad Simmons for t= heir exceptional advice, pictures, information—and encouragement. As with = most things done on this airplane, I’m combining their excellent recommendations to hopefully make a long-lasting and reliable fix.

=A0

See you at Oshkosh!

 

Bob

 

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