X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 01 Aug 2008 13:07:32 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m24.mx.aol.com ([64.12.137.5] verified) by logan.com (CommuniGate Pro SMTP 5.2.5) with ESMTP id 3050468 for lml@lancaironline.net; Thu, 31 Jul 2008 18:11:49 -0400 Received: from Sky2high@aol.com by imo-m24.mx.aol.com (mail_out_v38_r9.4.) id q.c1d.454a43cf (32914) for ; Thu, 31 Jul 2008 18:11:47 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Thu, 31 Jul 2008 18:11:45 EDT Subject: Re: [LML] LNC2 Vibration X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1217542305" X-Mailer: Unknown sub 34 X-Spam-Flag:NO -------------------------------1217542305 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Tom, 1. Because of the design of Matco wheel and bearings, the wheels must be bolted up tight - that is, while the plane is up on jacks, the axle nuts must be tight enough that an attempt to spin the wheels means that they make no more than 1/4 to 1/2 turn. Loose wheels can cause damage to the bearings and their surfaces as they are rattling around. 2. You should try to maintain about 50 psi in the mains and about 38-40 in the nose. Low inflation pressure can lead to premature wear on the inner tubes and ultimately a flat tire. 3. Inspect nose tire for "cupping" - an uneven outer edge. Cupped tires can lead to apparent vibration at certain rolling speeds. 4. Alignment of the mains can be mechanically checked, however the wear pattern on the tires may be revealing. 5. You should check the damping of the nose gear. - usually 2 steel plates with grease between them placed under the nose wheel. There should be reasonable resistance (damping) when you try to turn the wheel by hand. If not, the strut may have to be rebuilt or serviced. You may need weight on the nose gear so the "self-centering" mechanism is not engaged when the wheel is turned. If you accomplish these tasks, you have passed "Lawn Dart Landing Gear Maintenance 101". Grayhawk PS You could always remove the rotors and check them for "warping" against a flat surface (laminated composite wood shelf material from Lowes or Home Depot). In a message dated 7/31/2008 2:27:32 P.M. Central Daylight Time, dudewanarace@yahoo.com writes: Before I go and over engineer a problem, I thought I would get every ones expert advice first. It clearly has worked well for me in the past. (Thanks Grayhawk) I have what feels to be a classic case of warped rotors, but that isn't it. About the last half of the roll out I start to get a vibration from the right main gear. Or at least I think it is the right side. Thinking it was an easy fix I replaced the rotors with a new set. I think it is better, but that could be just in my head. The vibration is much worse under braking, but does exist while just rolling. As most vibrations, it seems to have a peak intensity at a certain speed. 30-50 mph I would guess. This has the original rubber cushion landing gear. So, here are my ideas.. Bad tire that is out of balance? Waaay out of balance. They are Chang Shin tires, so maybe I got what I paid for. haha Out of Alignment? This aircraft has had the service bulletin completed regarding the main gear reinforcement. Could this have caused an alignment issue? Nature of the beast? It has had this problem from the day I purchased it, so maybe it is just me. Although I hope not! Would love to hear some ideas or past experience with this. Thank a ton! Tom McNerney N54SG -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html **************Get fantasy football with free live scoring. Sign up for FanHouse Fantasy Football today. (http://www.fanhouse.com/fantasyaffair?ncid=aolspr00050000000020) -------------------------------1217542305 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
Tom,
 
1.  Because of the design of Matco wheel and bearings, the wheels=20= must=20 be bolted up tight - that is, while the plane is up on jacks, the axle=20= nuts=20 must be tight enough that an attempt to spin the wheels means that they make= no=20 more than 1/4 to 1/2 turn.  Loose wheels can cause damage to the bearin= gs=20 and their surfaces as they are rattling around. 
 
2. You should try to maintain about 50 psi in the mains and=20 about 38-40 in the nose.  Low inflation pressure can lead to prema= ture=20 wear on the inner tubes and ultimately a flat tire.
 
3. Inspect nose tire for "cupping" - an uneven outer edge.  Cupped= =20 tires can lead to apparent vibration at certain rolling speeds.
 
4. Alignment of the mains can be mechanically checked, however the wear= =20 pattern on the tires may be revealing.
 
5. You should check the damping of the nose gear.  - usually 2 ste= el=20 plates with grease between them placed under the nose wheel.  There sho= uld=20 be reasonable resistance (damping) when you try to turn the wheel by=20 hand.    If not, the strut may have to be rebuilt or=20 serviced.  You may need weight on the nose gear so the "self-centering"= =20 mechanism is not engaged when the wheel is turned.
 
If you accomplish these tasks, you have passed "Lawn Dart Landing Gear=20 Maintenance 101".
 
Grayhawk
 
PS  You could always remove the rotors and check them for=20 "warping" against a flat surface (laminated composite wood shelf=20 material from Lowes or Home Depot).
 
In a message dated 7/31/2008 2:27:32 P.M. Central Daylight Time,=20 dudewanarace@yahoo.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Before I=20 go and over engineer a problem, I thought I would get every ones expert ad= vice=20 first.  It clearly has worked well for me in the past. (Thanks=20 Grayhawk) 
 
I have what feels to be a classic case of war= ped=20 rotors, but that isn't it.  About the last half of the roll out I sta= rt=20 to get a vibration from the right main gear.  Or at least I think it=20= is=20 the right side.  Thinking it was an easy fix I replaced the rotors wi= th a=20 new set.  I think it is better, but that could be just in my head.&nb= sp;=20 The vibration is much worse under braking, but does exist while just=20 rolling.  As most vibrations, it seems to have a peak intensity at a=20 certain speed. 30-50 mph I would guess.  This has the original rubber= =20 cushion landing gear.
 
So, here are my ideas..
 
Ba= d=20 tire that is out of balance?  Waaay out of balance. They are Chang Sh= in=20 tires, so maybe I got what I paid for.  haha
 
Out of=20 Alignment? This aircraft has had the service bulletin completed regar= ding=20 the main gear reinforcement.  Could this have caused an alignmen= t=20 issue? 
 
Nature of the beast?  It has had this probl= em=20 from the day I purchased it, so maybe it is just me. Although I hope=20 not!
 
Would love to hear some ideas or past experience with=20 this.
 
Thank a ton!
Tom McNerney
N54SG

--
For=20 archives and unsub=20 http://mail.lancaironline.net:81/lists/lml/List.html


Get fantasy football with fre= e live scoring. Sign up for FanHouse Fantasy Football to= day.
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