X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 20 Apr 2011 08:05:28 -0400 Message-ID: X-Original-Return-Path: Received: from imr-ma04.mx.aol.com ([64.12.206.42] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4951419 for lml@lancaironline.net; Tue, 19 Apr 2011 20:31:58 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.206.42; envelope-from=VTAILJEFF@aol.com Received: from imo-ma01.mx.aol.com (imo-ma01.mx.aol.com [64.12.78.136]) by imr-ma04.mx.aol.com (8.14.1/8.14.1) with ESMTP id p3K0VFvN027817 for ; Tue, 19 Apr 2011 20:31:15 -0400 Received: from VTAILJEFF@aol.com by imo-ma01.mx.aol.com (mail_out_v42.9.) id q.e63.fcbb75f (43908) for ; Tue, 19 Apr 2011 20:31:11 -0400 (EDT) Received: from smtprly-md03.mx.aol.com (smtprly-md03.mx.aol.com [64.12.143.156]) by cia-dc07.mx.aol.com (v129.9) with ESMTP id MAILCIADC075-d4354dae294e9b; Tue, 19 Apr 2011 20:31:11 -0400 Received: from webmail-d100 (webmail-d100.sim.aol.com [205.188.255.1]) by smtprly-md03.mx.aol.com (v129.9) with ESMTP id MAILSMTPRLYMD034-d4354dae294e9b; Tue, 19 Apr 2011 20:31:10 -0400 References: X-Original-To: lml@lancaironline.net Subject: Re: [LML] Re: Gear operation fix for the LNC2 X-Original-Date: Tue, 19 Apr 2011 20:31:10 -0400 X-AOL-IP: 24.107.65.42 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: vtailjeff@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8CDCD09615456F5_10AC_107CB_webmail-d100.sysops.aol.com" X-Mailer: AOL Webmail 33540-STANDARD Received: from 24.107.65.42 by webmail-d100.sysops.aol.com (205.188.255.1) with HTTP (WebMailUI); Tue, 19 Apr 2011 20:31:10 -0400 X-Original-Message-Id: <8CDCD09614D32C6-10AC-8E4C@webmail-d100.sysops.aol.com> X-Spam-Flag:NO X-AOL-SENDER: VTAILJEFF@aol.com ----------MB_8CDCD09615456F5_10AC_107CB_webmail-d100.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" Bill, What was the cause of the engine failure? Jeff -----Original Message----- From: GT Phantom To: lml@lancaironline.net Sent: Tue, Apr 19, 2011 5:13 pm Subject: [LML] Re: Gear operation fix for the LNC2 Wolfgang, I know that this was discussed a while back, but it occurs to me that this= module could induce catastrophic failure if it activates a few times in= flight, e.g. if the pressure for some ungodly reason is NOT relieved the= pump could build up so much pressure that it blows a seal or worse. Bypassing the pressure switches AUTOMATICALLY is not, IMHO, an actual solu= tion but rather a work-around that could unintentionally cause unexpected= consequences. While fixing the pump with the latest mods and installing= the three-way dump valve is probably the best actual solution (fix the pr= oblem, not the symptoms), if you want to do a work-around it's probably sa= fer to use the momentary push-button solution (e.g. manually bypassing the= pressure switch by intentional pilot command) than to have an automatic= system repeatedly exercising a workaround without the pilot's knowledge. Everyone, By now some of you know that I experienced engine loss a few months ago an= d ended up attempting to land on a highway. Unfortunately an SUV pulled= onto the highway at the last moment, and the energy spent waiting to get= past the SUV was simply too much to leave enough for a flare. The result= was a hard touchdown, breaking off the left main and slamming the left wi= ngtip onto the highway. The plane pulled hard left, leaving me concerned= that the plane would cross the grass median into oncoming traffic. There= was just enough energy left to momentarily re-raise the left wing, apply= the right brake and rudder to straighten out, and make a split second dec= ision as to whether I could land on two wheels safely or whether attemptin= g that would result in either resuming course towards oncoming traffic or= result in flipping in the median. Given the choice, I chose to raise the= remaining gear and slide rather than risk flipping and being trapped in= a scenario that might possibly have involved gasoline leaking on a hot en= gine with us trapped inside. Google N351E for photos of the result. Why is that pertinent to this discussion? Prior to that I had had a gear-up landing from pump failure and other fact= ors involving a potential partner. I spent 3 yrs of weekends rebuilding= and a year flying before this incident. In the mean time, I became VERY= familiar with my systems. And, I just don't want to see any more of our= community end up busting their ass if it is avoidable or spending your ti= me fixing what might have remained a perfectly good airplane. SOooooooo.... =20 Chris has made an EXTREMELY generous offer to all of you. If you don't KN= OW that your pump has the latest mods, take him up on it. He is sharp and= an obsessively careful individual.=20 Install the 3-way valve if you have the time and inclination. Install the= push-button override, too. But do NOT install automated work-arounds that may be disguising or exacer= bating real problems. Please. Blue skies, Bill Reister From: Wolfgang To: lml@lancaironline.net Sent: Sun, April 17, 2011 10:13:18 AM Subject: [LML] Gear operation fix for the LNC2 Here are some details on the Gear Fix Module - - - - - There is a potential for the landing gear to fail to operate in the LNC2. =20 The spool in the hydraulic pump can come off it's end position and seal th= e fluid volume in the lines. When the system incurs a large temperature ri= se, the trapped fluid expands raising the pressure in the lines, tripping= both pressure switches open and making the hydraulic pump inoperable. =20 A module to fix this gear operation failure in the LNC2 using the standard= hydraulic system is now available. It is installed across the pressure sw= itches and monitors their operation. If both switches are tripped open by= high pressure, the pump is made to run in the direction set by the gear= switch re-seating the spool in it's end position restoring normal pump op= eration and relieving pressure in the offending side. This happens automat= ically without pilot intervention. =20 The module is 2.5" x 1.5" x .75", weighs 2.3 oz. and has two pairs of lead= s that connect directly to each pressure switch with 1/4" spade terminals.= No other wiring is necessary. Price is $250.00 each. Simple installation= instructions included. =20 Contact Wolfgang Franke at 248-471-2000 or Wolfgang@MiCom.net =20 ----- Original Message -----=20 From: Bryan Wullner=20 To: lml@lancaironline.net=20 Sent: Saturday, April 16, 2011 8:24 PM Subject: Re: [LML] Re: LNC2 Gear Hydraulics Wolfgang,=20 What is your gear fix module? Bryan On Fri, Apr 15, 2011 at 10:11 AM, Wolfgang wrote: From a design point of view, I still have a big concern about relying on= the friction from an O-ring to keep the landing gear functioning properly= . Vibration levels can exceed 70 G's. I would be much happier with a sprin= g loaded ball detent or something similar. =20 That's why I came up with the gear fix module. =20 Wolfgang =20 ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 Sent: Wednesday, April 13, 2011 8:25 AM Subject: Re: [LML] Re: LNC2 Gear Hydraulics A symmetric back-pressure circuit and spool will eliminate the possibility= of installing the spool backwards as happened with pumps manufactured in= about the '96 through '98 time frame. The spool must still remain in pla= ce after the pump shuts down to prevent both high and low circuits from lo= cking up simultaneously. Using o-ring 013-70 requires 30 g's to move the spool. Using o-ring 013-90 requires 70 g's to move the spool. This includes the return force generated by the poppet springs (410462).= =20 The difference between the two o-rings is durometer. I have been using th= e softer one without any problems. The stiffer o-ring (intended for pumps= with back pressure circuits) should leave no doubt. The first thing to= do with a pump that has a history of locking up both sides is to measure= the return force for the spool and make sure it has an o-ring installed. =20 Chris Zavatson N91CZ 360std www.N91CZ.net From: Wolfgang To: lml@lancaironline.net Sent: Mon, April 11, 2011 4:56:57 AM Subject: [LML] Re: LNC2 Gear Hydraulics When I first got into this problem with the hydraulic pumps last year, I= had a few conversations with the product manager of the Oildyne 108 pump.= There have been many changes in it's production life and one of them was= to make the spool symmetrical and have the relief circuit the same both= ways. =20 Wolfgang Wolfgang, Yes, I have considered this. The spool with O-ring is a very tight fight.= While I have not tried to measure the force to move it, I would estimate= something over 50 g's to move it (I'll measure this the next time I have= a pump opened up) Could it be that a pump somehow ended up mounted such= that it was subjected to some resonant frequency? Seems like a remote po= ssibilty given all the variables and the mass of the pump. How about we= ar and tear? Perhaps sitting dry and idle for ten years would do it. A= missing O-ring or a spool that doesn't utilize an O-ring would allow the= spool to move very easily. Parker does make spools that don't even have= O-rings. Did these end up getting installed by chance? Based on reports from the LML, the behavior seems to be rather binary. On= the one hand we have planes with over 1000 hours and more than ten years= of service that have never once had the spool move off the poppet. On th= e other hand, we have planes with circuits that lock up right out of the= box (put into service). This leads me to believe there is a difference in configuration. The easi= est way to verify this is to simply open up a pump that is known to lock= up hi and low circuits simultaneously. While I have opened up several pumps (primarily to flip around spool valve= s), I have not yet worked on one that had this lock up issue. I am optimi= stic the difference will be quite obvious upon inspection. =20 Chris Zavatson N91CZ 360std www.N91CZ.net Sent from my iPad On Apr 7, 2011, at 11:53 AM, "Wolfgang" wrote: Chris, have you considered what effect airframe vibration has on the posit= ion of the spool in the pump and the problem in general ? =20 Wolfgang From: Chris Sender: Subject: Re: [LML] Re: LNC2 Gear Hydraulics Date: Wed, 06 Apr 2011 07:38:35 -0400 To: lml@lancaironline.net I would like to extend the offer to the whole group. I think the entire= community would benefit from understanding why some pumps are allowing th= e system to lock up. If anyone has a pump that exhibits this behavior and= could part with it for a week, I am willing to check it out on the test= stand and examine the internal configuration. Chris Zavatson N91CZ 360std www.N91CZ.net -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.htm= l ----------MB_8CDCD09615456F5_10AC_107CB_webmail-d100.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="us-ascii"
Bill,
 
What was the cause of the engine failure?
 
Jeff



-----Original Message-----
From: GT Phantom <gt_phantom@hotmail.com>
To: lml@lancaironline.net
Sent: Tue, Apr 19, 2011 5:13 pm
Subject: [LML] Re: Gear operation fix for the LNC2

Wolfgang,

I know that this was discussed a while back, but it occurs to me that this= module could induce catastrophic failure if it activates a few times in= flight, e.g. if the pressure for some ungodly reason is NOT relieved the= pump could build up so much pressure that it blows a seal or worse.

Bypassing the pressure switches AUTOMATICALLY is not, IMHO, an actual solu= tion but rather a work-around that could unintentionally cause unexpected= consequences.  While fixing the pump with the latest mods and instal= ling the three-way dump valve is probably the best actual solution (fix th= e problem, not the symptoms), if you want to do a work-around it's probabl= y safer to use the momentary push-button solution (e.g. manually bypassing= the pressure switch by intentional pilot command) than to have an automat= ic system repeatedly exercising a workaround without the pilot's knowledge= .

Everyone,

By now some of you know that I experienced engine loss a few months ago an= d ended up attempting to land on a highway.  Unfortunately an SUV pul= led onto the highway at the last moment, and the energy spent waiting to= get past the SUV was simply too much to leave enough for a flare. = The result was a hard touchdown, breaking off the left main and slamming= the left wingtip onto the highway.  The plane pulled hard left, leav= ing me concerned that the plane would cross the grass median into oncoming= traffic.  There was just enough energy left to momentarily re-raise= the left wing, apply the right brake and rudder to straighten out, and ma= ke a split second decision as to whether I could land on two wheels safely= or whether attempting that would result in either resuming course towards= oncoming traffic or result in flipping in the median.  Given the cho= ice, I chose to raise the remaining gear and slide rather than risk flippi= ng and being trapped in a scenario that might possibly have involved gasol= ine leaking on a hot engine with us trapped inside.  Google N351E for= photos of the result.

Why is that pertinent to this discussion?

Prior to that I had had a gear-up landing from pump failure and other fact= ors involving a potential partner.  I spent 3 yrs of weekends rebuild= ing and a year flying before this incident.  In the mean time, I beca= me VERY familiar with my systems.  And, I just don't want to see any= more of our community end up busting their ass if it is avoidable or spen= ding your time fixing what might have remained a perfectly good airplane.<= br>
SOooooooo.... 

Chris has made an EXTREMELY generous offer to all of you.  If you don= 't KNOW that your pump has the latest mods, take him up on it.  He is= sharp and an obsessively careful individual.

Install the 3-way valve if you have the time and inclination.  Instal= l the push-button override, too.

But do NOT install automated work-arounds that may be disguising or exacer= bating real problems.

Please.

Blue skies,

Bill Reister


From: Wolfgang <Wolfgang@MiCo= m.net>
To: lml@lancaironline.net<= /A>
Sent: Sun, April 17, 2011= 10:13:18 AM
Subject: [LML] Gear operat= ion fix for the LNC2

Here are some details on the Gear Fix Mod= ule - - - - -
There is a potential for the landing gear= to fail to operate in the LNC2.
 
The spool in the hydraulic pump can come= off it's end position and seal the fluid volume in the lines. When the sy= stem incurs a large temperature rise, the trapped fluid expands raising th= e pressure in the lines, tripping both pressure switches open and mak= ing the hydraulic pump inoperable.
 
A module to fix this gear operation failu= re in the LNC2 using the standard hydraulic system is now available.= It is installed across the pressure switches and monitors their operation= . If both switches are tripped open by high pressure, the pump is mad= e to run in the direction set by the gear switch re-seating the spool in= it's end position restoring normal pump operation and relieving pres= sure in the offending side. This happens automatically without pilot inter= vention.
 
The module is 2.5" x 1.5" x .75", we= ighs 2.3 oz. and has two pairs of leads that connect directly to each= pressure switch with 1/4" spade terminals. No other wiring is necessary.= Price is $250.00 each. Simple installation instructions included.<= /div>
 

 
----- Original Message -----
Sent: Saturday, April 16, 2011 8:24= PM
Subject: Re: [LML] Re: LNC2 Gear Hy= draulics

Wolfgang,=20
What is your gear fix module?
Bryan

On Fri, Apr 15, 2011 at 10:11 AM, Wolfgang <Wolfga= ng@micom.net> wrote:
From a design point of view, I still have= a big concern about relying on the friction from an O-ring to keep the la= nding gear functioning properly. Vibration levels can exceed 70 G's. I wou= ld be much happier with a spring loaded ball detent or something similar.<= /FONT>
 
That's why I came up with the gear fix&nb= sp;module.
 
Wolfgang
 
----- Original Message -----
Sent: Wednesday, April 13, 2011 8:2= 5 AM
Subject: Re: [LML] Re: LNC2 Gear Hy= draulics

A symmetric back-pressure circuit and spool will eliminate the possib= ility of installing the spool backwards as happened with pumps manufacture= d in about the '96 through '98 time frame.  The spool must still rema= in in place after the pump shuts down to prevent both high and low circuit= s from locking up simultaneously.
Using o-ring 013-70 requires 30 g's to move the spool.
Using o-ring 013-90 requires 70 g's to move the spool.
This includes the return force generated by the poppet springs (410462).&n= bsp;
The difference between the two o-rings is durometer.  I have bee= n using the softer one without any problems.  The stiffer o-ring (int= ended for pumps with back pressure circuits) should leave no doubt. = The first thing to do with a pump that has a history of locking up both= sides is to measure the return force for the spool and make sure it has= an o-ring installed.
 
Chris Zavatson
N91CZ
360std
From: Wolfgang <Wolfgang@MiCo= m.net>
To: lml@lancaironline.net
Sent: Mon, April 11, 2011= 4:56:57 AM
Subject: [LML] Re: LNC2 Ge= ar Hydraulics

When I first got into this problem with= the hydraulic pumps last year, I had a few conversations with the product= manager of the Oildyne 108 pump. There have been many changes in it's pro= duction life and one of them was to make the spool symmetrical and have th= e relief circuit the same both ways.
 
Wolfgang
Wolfgang,
Yes, I have considered this.  The spool with O-ring is a very ti= ght fight.  While I have not tried to measure the force to move it,= I would estimate something over 50 g's to move it (I'll measure this the= next time I have a pump opened up)  Could it be that a pump somehow= ended up mounted such that it was subjected to some resonant frequency?=  Seems like a remote possibilty given all the variables and the mass= of the pump.    How about wear and tear?  Perhaps sitting dry and idle for ten years would do it.  A mi= ssing O-ring or a spool that doesn't utilize an O-ring would allow the spo= ol to move very easily.  Parker does make spools that don't even have= O-rings.  Did these end up getting installed by chance?

Based on reports from the LML, the behavior seems to be rather= binary.  On the one hand we have planes with over 1000 hours and mor= e than ten years of service that have never once had the spool move off th= e poppet.  On the other hand, we have planes with circuits that lock= up right out of the box (put into service).
This leads me to believe there is a difference in configuration= .  The easiest way to verify this is to simply open up a pump that is= known to lock up hi and low circuits simultaneously.

While I have opened up several pumps (primarily to flip around spool= valves), I have not yet worked on one that had this lock up issue.  = I am optimistic the difference will be quite obvious upon inspection. &nbs= p;

Chris Zavatson
N91CZ
360std


Sent from my iPad

On Apr 7, 2011, at 11:53 AM, "Wolfgang" <Wolfgang@MiCom.net> wrote:

Chris, have you considered what effect ai= rframe vibration has on the position of the spool in the pump and the prob= lem in general ?
 
Wolfgang
From: Chris <c= hris_zavatson@yahoo.com>
Sender: <marv@lanc= aironline.net>
Subject: Re: [LML] Re: LNC2 Gear Hydraulics
Date: Wed, 06 Apr 2011 07:38:35 -0400
To: lml@lancaironl= ine.net
I would like to extend the offer to the whole group.  I think th= e entire community would benefit from understanding why some pumps are all= owing the system to lock up.  If anyone has a pump that exhibits this= behavior and could part with it for a week, I am willing to check it out= on the test stand and examine the internal configuration.

Chris Zavatson
N91CZ
360std

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