X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 50 [XX] Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 22 Apr 2007 11:36:31 -0400 Message-ID: X-Original-Return-Path: Received: from mtai04.charter.net ([209.225.8.184] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 1998550 for lml@lancaironline.net; Sun, 22 Apr 2007 08:44:46 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.225.8.184; envelope-from=LHenney@charter.net Received: from aa05.charter.net ([10.20.200.157]) by mtai04.charter.net (InterMail vM.7.08.02.00 201-2186-121-20061213) with ESMTP id <20070422124344.UFUI1421.mtai04.charter.net@aa05.charter.net>; Sun, 22 Apr 2007 08:43:44 -0400 Received: from CYBERMAX ([68.116.130.237]) by aa05.charter.net with ESMTP id <20070422124344.FWWO9261.aa05.charter.net@CYBERMAX>; Sun, 22 Apr 2007 08:43:44 -0400 From: "Larry Henney" X-Original-To: "Lancair List" X-Original-Cc: "Dick Keyt" , "Don & Shirley Saint" , "Mike Henney" Subject: L360 Nose Gear Collapse, The Adventure, The Cause X-Original-Date: Sun, 22 Apr 2007 07:45:58 -0500 X-Original-Message-ID: <003d01c784dc$2d2f61e0$640fa8c0@CYBERMAX> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_003E_01C784B2.445959E0" X-Mailer: Microsoft Office Outlook 11 Thread-Index: AceE3Cwqkae1rEcSQnqDZGNHOe6WYQ== X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Chzlrs: 0 This is a multi-part message in MIME format. ------=_NextPart_000_003E_01C784B2.445959E0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Guys, As I read with great interest last month the saga of possible improvements to the L360 scissor link systems I deemed it appropriate to give a thorough inspection to mine on my annual next month. Lo and Behold my annual came early. Upon taxi out the other day I was following my home owners association request to avoid the new taxi way. We have several acres by which I can get to my runway. It was crappy and rough for years so the HOA finally acknowledged who owned that parcel and accepted responsibility to make it a functional taxi way. The HOA started there project last fall by bringing in 5 yards of dirt and a half hour of grading. By"avoid" we mean to taxi across the end of the new taxiway and stay off the remaining couple hundred feet to let the grass grow. Long story short, it has been a dirt mud pit since last fall. This spring an irrigation line was added. Excitement was building. Rumor had it that seed would soon follow. There still was no grass on the new dirt so we would taxi across the new taxiway at the beginning and then down the hill to the runway. All that is to say I deliquately taxied across the dirt taxiway and stuck the right main in the adjacent soft irrigation line trench. Moments later (or less) the prop visited the earth. What happened? I figured the side loads on the nose strut caused my "weak" scissor to fail. Indeed the scissor lower link was in 3 parts. But there were more parts in spaghetti mode. Both hyd cylinders were askew and the nitrogen strut had a 30 degree bend in the rod. The main T boss (part number GM-?) was attached by only on end. You know the part, the chromoly piece in the top of the wheel well with the 3/8" pivot rod going through the nose tunnel? The T Boss attach point appears to be the primary initiator of the failure sequence. Upon close inspection, the 3/8" pivot rod had been rotating with the moving piece (read, lack of lube). The cotter key in cockpit was found in pieces (under the EAR stick on insulation- who knows why I tolerated that invisibility.... out of site out of mind..) Anyway, the rod appears to have been easing it's way West for several gear cycles. The little bump into the irrigation line trench appears to have been the last straw allowing the East end of the rod to swing freely with the help of the nitrogen strut and bend the 3/8" pivot, unleashing all manor of devilish forces. The fix.... May be nothing in your case. I believe larger cotter keys, inspection, and annual lubrication would have eliminated the problem. I seem to remember not knowing much about drilling stainless back in the day. My cotter key was a wee little piece. However, there are at least two additional things I am going to do to repair mine. First, I'll add a grease zirt to the T Boss part so I can get lube to the 3/8" bushings. Additionally, I'll use a roll pin on one end of the 3/8" pivot rod. In conjunction with the roll pin will be a slotted mating piece of phenolic. This will eliminate any possibility of the axle ever turning. That's what I'm looking at so far. I'd like to hear any other suggestions. BTW, the scissor link ("weak part") had very pretty holes after 700 hours and probably as many landings. So far, I'm inclined to install new Lancair scissors and inspect annually. Of course my good neighbor and fellow race junky Dick Keyt is recommending Titanium. The key to that whole hydraulic over center link conversation (including the mains) requires zero hydraulic over center force. I assume that's a dead horse on the list? Larry Henney N360LH 700 hours Still "The fastest LNC2 in the Western Hemisphere" Next race... May 19 http://sportairrace.org/ Be there! PS: Did I mention the prop hit the ground... Da*&%$#! PSS: Oh yeah, the taxiway? 60 Workers daily all week. It is now a sodded, rolled, pressed, groomed, fertilized, irrigated, putting green. They must've thought their irrigation trench had something to do with my nose gear collapse. Remember, it is preferable to collapse one's nose gear while taxiing as opposed to flight. ------=_NextPart_000_003E_01C784B2.445959E0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
Guys,
 
As I = read with great=20 interest last month the saga of possible improvements to the L360 = scissor link=20 systems I deemed it appropriate to give a thorough inspection to mine on = my=20 annual next month.  Lo and Behold my annual came = early.
 
Upon = taxi out the=20 other day I was following my home owners association request to = avoid the=20 new taxi way.  We have several acres by which I can get to my = runway. =20 It was crappy and rough for years so the HOA finally acknowledged who = owned that=20 parcel and accepted responsibility to make it a functional taxi = way.  The=20 HOA started there project last fall by bringing in 5 yards of dirt and a = half=20 hour of grading.
 
By"avoid" we mean to=20 taxi across the end of the new taxiway and stay off the remaining couple = hundred=20 feet to let the grass grow.  Long story short, it has been a = dirt mud=20 pit since last fall.  This spring an irrigation line was = added. =20 Excitement was building.  Rumor had it that seed would soon = follow. =20 There still was no grass on the new dirt so we would taxi across the new = taxiway=20 at the beginning and then down the hill to the = runway.
 
All = that is to say I=20 deliquately taxied across the dirt taxiway and stuck the right = main in=20 the adjacent soft irrigation line trench.  Moments later (or=20 less) the prop visited the earth.
 
What = happened? =20 I figured the side loads on the nose strut caused my "weak" scissor to=20 fail.  Indeed the scissor lower link was in 3 parts.  But = there were=20 more parts in spaghetti mode.  Both hyd cylinders were askew and = the=20 nitrogen strut had a 30 degree bend in the rod.  The main T boss = (part=20 number GM-?) was attached by only on end.  You know the part, the = chromoly=20 piece in the top of the wheel well with the 3/8" pivot rod going through = the=20 nose tunnel? 
 
The T = Boss attach=20 point appears to be the primary initiator of the failure=20 sequence.  Upon close inspection, the 3/8" pivot rod had been = rotating=20 with the moving piece (read, lack of lube).  The cotter key in = cockpit was=20 found in pieces (under the EAR stick on insulation- who knows why I = tolerated=20 that invisibility.... out of site out of mind..) Anyway, the rod appears = to have=20 been easing it's way West for several gear cycles.  The little bump = into=20 the irrigation line trench appears to have been the last straw allowing = the East=20 end of the rod to swing freely with the help of the nitrogen strut and = bend the=20 3/8" pivot, unleashing all manor of devilish forces.
 
The = fix.... =20 May be nothing in your case.  I believe larger cotter keys, = inspection, and=20 annual lubrication would have eliminated the problem.  I = seem to=20 remember not knowing much about drilling stainless back in the = day.  My=20 cotter key was a wee little piece.  However, there are at least two = additional things I am going to do to repair mine.  First, I'll add = a=20 grease zirt to the T Boss part so I can get lube to the 3/8" = bushings. =20 Additionally, I'll use a roll pin on one end of the 3/8" pivot = rod. =20 In conjunction with the roll pin will be a slotted mating piece of=20 phenolic.  This will eliminate any possibility of the axle = ever=20 turning.
 
That's = what I'm=20 looking at so far.  I'd like to hear any other=20 suggestions.
 
BTW, = the scissor=20 link ("weak part") had very pretty holes after 700 hours and probably as = many=20 landings.  So far, I'm inclined to install new Lancair scissors and = inspect=20 annually.  Of course my good neighbor and fellow race junky Dick = Keyt is=20 recommending Titanium.
 
The = key to that=20 whole hydraulic over center link conversation (including the=20 mains) requires zero hydraulic over center=20 force. I assume that's a dead horse on the=20 list?
 
Larry=20 Henney
N360LH = 700=20 hours
Still = "The fastest=20 LNC2 in the Western Hemisphere"
Next race... May 19 http://sportairrace.org/ Be=20 there!
 
PS:  Did I=20 mention the prop hit the ground... Da*&%$#!
 
PSS: = Oh yeah, the=20 taxiway?  60 Workers daily all week.  It is now a sodded, = rolled,=20 pressed, groomed, fertilized, irrigated, putting green.  They = must've=20 thought their irrigation trench had something to do with my nose gear=20 collapse.
 
Remember, it is=20 preferable to collapse one's nose gear while taxiing as = opposed=20 to flight.
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