X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 21 Dec 2012 07:47:44 -0500 Message-ID: X-Original-Return-Path: Received: from webmail.emmett.org ([75.147.240.42] verified) by logan.com (CommuniGate Pro SMTP 6.0) with ESMTPS id 5962015 for lml@lancaironline.net; Fri, 21 Dec 2012 07:03:27 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.147.240.42; envelope-from=sbuller@emmett.org Received: from EMMETTSERVER.emmett.local ([fe80::3914:271a:9fbf:ccce]) by EMMETTSERVER.emmett.local ([fe80::3914:271a:9fbf:ccce%10]) with mapi id 14.01.0355.002; Fri, 21 Dec 2012 07:02:50 -0500 From: Steve Buller X-Original-To: Lancair Mailing List Subject: RE: [LML] IV maingear lock down pin spring Thread-Topic: [LML] IV maingear lock down pin spring Thread-Index: AQHN3t1q3UzCT5qGI02v/1K633WTY5gjJ2bg X-Original-Date: Fri, 21 Dec 2012 12:02:49 +0000 X-Original-Message-ID: <144B9F97D0F6E34980160899EF1014E93CB5FCE4@EMMETTSERVER.emmett.local> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.10.240.26] x-avast-antispam: clean, score=2 x-original-content-type: application/ms-tnef Content-Type: multipart/alternative; boundary="_000_144B9F97D0F6E34980160899EF1014E93CB5FCE4EMMETTSERVERemm_" MIME-Version: 1.0 --_000_144B9F97D0F6E34980160899EF1014E93CB5FCE4EMMETTSERVERemm_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Hay there K K, Did Lancair tell you what year they made the change from 6 to 7 pairs of sp= ring washers? Steve Buller From: k k [mailto:ktad9@hotmail.com] Sent: Thursday, December 20, 2012 1:11 PM To: lml@lancaironline.net Subject: [LML] IV maingear lock down pin spring Hello all, Sometime ago, I watched with surprise 2 separate videos each showing Lancai= r 4 main landing gear collapse during Taxiing, Well, I tested mine and with a force of about 50 Lbs pushing backwards on a= down locked gear, I was able to dislodge it and unlock the gear. Due to th= e design angle of the main gear leg, it is difficult to exert a backward fo= rce, since the weight of the airplane exerts a force to extend the gear fur= ther, With the exception of a rock or small pothole on the runway, the only= other situation I can imagine which exerts a backward force on the main ge= ar is Breaking while taxiing. As all of us probably aware of the lock down pin in the hydraulic cylinder = which is pushed down by a spring to engage it in a groove inorder to lock t= he gear in the down position. the spring is a series washers type stacked against each other in alternati= ng up and down position (6 pairs =3D total of 12 washers). they are sold at McMaster part # 9712k58 with a working load of 110 lbs and= a flat load of 175 lbs. I contacted Lancair and they said they changed the number of washers to imp= rove the spring to a total of 14 ( 7 pair) and they emailed me the drawing = which I am attaching in a PDF, however Lancair did not test it against sign= ificant loads. I have 2 questions, first, how far down the groove should the lock down pin= travel to secure a down lock position and maybe a mark on the pin above th= e piston retainer should be placed and checked every annual or so. The second, and probably will be subject of more discussion is, what is the= optimum number of washers in the spring? what is the minimum load it shoul= d exert? there is also an offline comments regarding replacing it with a sp= iral type spring, well these are questions for the techs and engineers in t= he group! Kamal IVP 1104T --_000_144B9F97D0F6E34980160899EF1014E93CB5FCE4EMMETTSERVERemm_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

 <= /p>

Hay there K K,=

Did Lancair tell you what= year they made the change from 6 to 7 pairs of spring washers?<= /span>

 <= /p>

 

 

Steve  Buller

 <= /p>

From: k k [mai= lto:ktad9@hotmail.com]
Sent: Thursday, December 20, 2012 1:11 PM
To: lml@lancaironline.net
Subject: [LML] IV maingear lock down pin spring

 


 Hello all,
 
Sometime ago, I watched with surprise 2 separate videos each showing L= ancair 4 main landing gear collapse during Taxiing,
Well, I tested mine and with a force of about 50 Lbs pushing backwards on a= down locked gear, I was able to dislodge it and unlock the gear. Due to th= e design angle of the main gear leg, it is difficult to exert a backward fo= rce, since the weight of the airplane exerts a force to extend the gear further, With the exception of a rock or= small pothole on the runway, the only other situation I can imagine w= hich exerts a backward force on the main gear is Breaking while taxiing. As all of us probably aware of the lock down pin in the hydraulic cylinder = which is pushed down by a spring to engage it in a groove inorder to lock t= he gear in the down position.
the spring is a series washers type stacked against each other in alternati= ng up and down position (6 pairs =3D total of 12 washers).
they are sold at McMaster part # 9712k58 with a working load of 110 lbs and= a flat load of 175 lbs.
I contacted Lancair and they said they changed the number of washers to imp= rove the spring to a total of 14 ( 7 pair) and they emailed me the dra= wing which I am attaching in a PDF, however Lancair did not test it against= significant loads.
I have 2 questions, first, how far down the groove should the lock down pin= travel to secure a down lock position and maybe a mark on the pin abo= ve the piston retainer should be placed and checked every annual or so.
The second, and probably will be subject of more discussion is, what i= s the optimum number of washers in the spring? what is the minimum load it = should exert? there is also an offline comments regarding replacing it with= a spiral type spring, well these are questions for the techs and engineers in the group!
 
Kamal
IVP 1104T

 

 

 

 

 

 

 


 
 
 
 
 
 
 

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