X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 10 Feb 2014 07:54:17 -0500 Message-ID: X-Original-Return-Path: Received: from mail-pa0-f50.google.com ([209.85.220.50] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6725568 for lml@lancaironline.net; Mon, 10 Feb 2014 04:50:54 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.220.50; envelope-from=frederickemoreno@gmail.com Received: by mail-pa0-f50.google.com with SMTP id kp14so5958587pab.23 for ; Mon, 10 Feb 2014 01:50:18 -0800 (PST) X-Received: by 10.68.201.163 with SMTP id kb3mr2176181pbc.168.1392025818724; Mon, 10 Feb 2014 01:50:18 -0800 (PST) X-Original-Return-Path: Received: from User-PC (CPE-124-178-176-245.lns4.pie.bigpond.net.au. [124.178.176.245]) by mx.google.com with ESMTPSA id id1sm40709233pbc.11.2014.02.10.01.50.16 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 10 Feb 2014 01:50:17 -0800 (PST) MIME-Version: 1.0 X-Original-Message-Id: <52F8A0D2.0000BB.10416@USER-PC> X-Original-Date: Mon, 10 Feb 2014 17:50:10 +0800 Content-Type: Multipart/Alternative; charset="iso-8859-1"; boundary="------------Boundary-00=_MZXRWEFCCJD000000000" X-Mailer: IncrediMail (6605288) From: "frederickemoreno@gmail.com" X-FID: FLAVOR00-NONE-0000-0000-000000000000 X-Priority: 3 X-Original-To: "Lancair Mail (lml@lancaironline.net)" Subject: Lancair IV landing gear issues --------------Boundary-00=_MZXRWEFCCJD000000000 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Many thanks to members for all the good ideas on why my mains tend to han= g down when retraction is selected. Particular thanks to those that sugges= ted investigating the "shuttle valve" on the back of the landing gear structu= ral box as the likely source of retraction failures that keep both mains in = the wells. =0D =0D We may well have two things going on intermittently: shuttle valve ball flopping to the wrong side occasionally which would stop both mains from going up and we have a couple of incidences of only one main coming up wh= ich must arise from some other cause. =0D =0D So we have made the decision to jack up the airplane, cycle with some careful observations, hand pump gear down while listening carefully for bubbles in the hand pump line when pressure is released, pull the actuato= rs and shuttle valve out (valve first), and carefully investigate and docume= nt. We also plan to replace all O rings, check O ring compressions (piston t= o cylinder O ring compression), and look for signs of locking pin wear or damage and locking slot possible damage. It was also suggested that we rotate both the locking pins and hydraulic pistons to shift the wear poin= t at pin/slot to another location. =0D =0D Will document carefully, take photos where it makes sense, and report.=20 Teardown won't be until mid-March due to schedule conflicts. =0D =0D Sadly an inquiry to Lancair was received and acknowledged by MIchelle, promptly forwarded to tech support, and thereafter.... Silence..... Which seems increasingly common from anecdotal reports collected from various builders contacting the factory with questions. =0D =0D Having no part numbers for O rings, we will have to take them to a hydraulics specialty shop and get or order replacements. Of course since= we are out in the boonies, this means sit and wait time before reassembly si= nce we can not pre-order anything. =0D =0D More to follow.=0D =0D Fred Moreno --------------Boundary-00=_MZXRWEFCCJD000000000 Content-Type: Text/HTML; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Many thanks to members for all the good ideas on why my mains tend t= o hang down when retraction is selected.  Particular thanks to those= that suggested investigating the "shuttle valve" on the back of the land= ing gear structural box as the likely source of retraction failures that = keep both  mains in the wells.
 
We may well have two things going on intermittently: shuttle valve b= all flopping to the wrong side occasionally which would stop both mains f= rom going up and we have a couple of incidences of only one main coming u= p which must arise from some other cause. 
 
So we have made the decision to jack up the airplane, cycle with som= e careful observations, hand pump gear down while listening carefully for= bubbles in the hand pump line when pressure is released, pull the actuat= ors and shuttle valve out (valve first), and carefully investigate and do= cument.  We also plan to replace all O rings, check O ring compressi= ons (piston to cylinder O ring compression), and look for signs of lockin= g pin wear or damage and locking slot possible damage.  It was also = suggested that we rotate both the locking pins and hydraulic pistons to s= hift the wear point at pin/slot to another location.
 
Will document carefully, take photos where it makes sense, and repor= t.  Teardown won't be until mid-March due to schedule conflicts.
 
Sadly an inquiry to Lancair was received and acknowledged by MIchell= e, promptly forwarded to tech support, and thereafter.... Silence..... Wh= ich seems increasingly common from anecdotal reports collected from vario= us builders contacting the factory with questions. 
 
Having no part numbers for O rings, we will have to take them to a h= ydraulics specialty shop and get or order replacements.  Of cou= rse since we are out in the boonies, this means sit and wait time before = reassembly since we can not pre-order anything.
 
More to follow.
 
Fred Moreno
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