X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 30 Jan 2006 12:49:56 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m27.mx.aol.com ([64.12.137.8] verified) by logan.com (CommuniGate Pro SMTP 5.0.7) with ESMTP id 960733 for lml@lancaironline.net; Mon, 30 Jan 2006 12:21:55 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.8; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m27.mx.aol.com (mail_out_v38_r6.3.) id q.147.55aaa402 (17377) for ; Mon, 30 Jan 2006 12:20:54 -0500 (EST) From: Sky2high@aol.com X-Original-Message-ID: <147.55aaa402.310fa4f5@aol.com> X-Original-Date: Mon, 30 Jan 2006 12:20:53 EST Subject: Re: [LML] Lancair 235 X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1138641653" X-Mailer: 9.0 Security Edition for Windows sub 5300 X-Spam-Flag: NO -------------------------------1138641653 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 1/30/2006 12:17:05 A.M. Central Standard Time, rpastusek@htii.com writes: First, with about 400 hours on the aircraft, he has considerable wear on the right aileron and right elevator hinges, as well as some play in the right aileron linkage. The combination allows visible flutter of the right aileron during high speed flight. He has not yet opened the linkage access panel to see what's worn in side, but will do so this week. When discussing hinge replacement, I advised him that some folks installed Teflon-lined hinges that were supposed to reduce wear. Could you provide recommendation as to the effectiveness of this, and a source for this material? Bob, The common material for "teflon" pins (ss welding rod and teflon spagetti) is slightly smaller than ordinary hinge pins. The looseness is actually worse as the teflon can flow a bit over time. Chris Zavatson and I use SS welding rod that is slightly larger than ordinary hinge pins and find no loss of smoothness or increased friction (3/32 dia, I think. Note that a ream was used to clean up the hinge). This will greatly reduce system lash. Additionally, I rig my ailerons slightly up for a small air load so that they do not bounce around in the very low force dead band at neutral. Even with the larger pins, I still see wear on the right elevator hinge - I am investigating airflow and airframe vibration harmonics (plus a too wiggly tail) to try to resolve the elevator condition. Second, the airplane can not be trimmed to level flight at high speed. With the trim full down, the stick must still be held forward to keep the nose on the horizon. We discussed installing a stronger spring on the trim system, but I told him we should ask the experts about this first. What's the best way to fix this? Did he shorten the elevator bell crank by 1 inch (a common mod)? If so, forces are raised (throw reduced) and a stiffer spring is required. Also, the spring stops can be moved closer together to increase force although the trim could be maxed out anyway. Is he using the cruciform trim mechanism that relies on friction to hold the arm position? If so, the stiffer spring requires a greater friction and more effort to move the trim arm. Also, the trim grip on the elevator push rod could be moved slightly, but one must carefully check that there is plenty of up elevator for the so-called flare. Another aspect is where the flaps are reflexed to during cruise. If set too high, the nose pitch up forces are very pronounced. The flaps will move higher in flight than the angle set on the ground -- just pick them up by hand after they are rigged and that is where they will be during flight. He could try to slightly extend the flaps (reduce the reflex) and check the effect on speed and trim. Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) -------------------------------1138641653 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 1/30/2006 12:17:05 A.M. Central Standard Time,=20 rpastusek@htii.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
First, with about= 400=20 hours on the aircraft, he has considerable wear on the right aileron and r= ight=20 elevator hinges, as well as some play in the right aileron linkage. The=20 combination allows visible flutter of the right aileron during high speed=20 flight. He has not yet opened the linkage access panel to see what's worn=20= in=20 side, but will do so this week. When discussing hinge replacement, I advis= ed=20 him that some folks installed Teflon-lined hinges that were supposed to re= duce=20 wear. Could you provide recommendation as to the effectiveness of this, an= d a=20 source for this material?
 
Bob,
 
The common material for "teflon" pins (ss welding rod and teflon spaget= ti)=20 is slightly smaller than ordinary hinge pins.  The looseness is actuall= y=20 worse as the teflon can flow a bit over time.  Chris Zavatson and I use= SS=20 welding rod that is slightly larger than ordinary hinge pins and find no los= s of=20 smoothness or increased friction (3/32 dia, I think. Note that a ream w= as=20 used to clean up the hinge).  This will greatly reduce system lash.&nbs= p;=20 Additionally, I rig my ailerons slightly up for a small air load so tha= t=20 they do not bounce around in the very low force dead band at neutral.&n= bsp;=20 Even with the larger pins, I still see wear on the right elevator hinge - I=20= am=20 investigating airflow and airframe vibration harmonics (plus a too wiggly ta= il)=20 to try to resolve the elevator condition.
 
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Second, the airpl= ane can=20 not be trimmed to level flight at high speed. With the trim full down, the= =20 stick must still be held forward to keep the nose on the horizon. We discu= ssed=20 installing a stronger spring on the trim system, but I told him we should=20= ask=20 the experts about this first. What's the best way to fix=20 this?
Did he shorten the elevator bell crank by 1 inch (a common mod)? =20= If=20 so, forces are raised (throw reduced) and a stiffer spring is required. = ;=20 Also, the spring stops can be moved closer together to increase force althou= gh=20 the trim could be maxed out anyway.  Is he using the cruciform trim=20 mechanism that relies on friction to hold the arm position?  If so, the= =20 stiffer spring requires a greater friction and more effort to move the trim=20 arm.  Also, the trim grip on the elevator push rod could be moved sligh= tly,=20 but one must carefully check that there is plenty of up elevator for the=20 so-called flare.
 
Another aspect is where the flaps are reflexed to during cruise. =20= If=20 set too high, the nose pitch up forces are very pronounced.  The flaps=20= will=20 move higher in flight than the angle set on the ground -- just pick them up=20= by=20 hand after they are rigged and that is where they will be during flight.&nbs= p;=20 He could try to slightly extend the flaps (reduce the reflex) and check the=20 effect on speed and trim.
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)
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