X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 16 Apr 2009 22:16:35 -0400 Message-ID: X-Original-Return-Path: Received: from imr-m07.mx.aol.com ([64.12.138.209] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3584020 for lml@lancaironline.net; Thu, 16 Apr 2009 20:42:45 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.138.209; envelope-from=Sky2high@aol.com Received: from imo-ma01.mx.aol.com (imo-ma01.mx.aol.com [64.12.78.136]) by imr-m07.mx.aol.com (v107.10) with ESMTP id RELAYIN1-249e7d05d244; Thu, 16 Apr 2009 20:42:05 -0400 Received: from Sky2high@aol.com by imo-ma01.mx.aol.com (mail_out_v40_r1.5.) id q.c73.4e19fd02 (29678) for ; Thu, 16 Apr 2009 20:41:57 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Thu, 16 Apr 2009 20:41:57 EDT Subject: Re: [LML] AW: Gear Free Fall X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1239928917" X-Mailer: AOL 9.1 sub 5006 X-Spam-Flag:NO X-AOL-IP: 64.12.78.136 -------------------------------1239928917 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en Johannes, I have never had the condition you mention happen to me. In my system there has always been a path back to the pump reservoir, thru the pump va= lves. Scott Krueger In a message dated 4/16/2009 1:59:18 P.M. Central Daylight Time, jschredl@web.de writes: Dom, I can confirm your observations! Many years ago I dicussed this subject with NEICO and gave them following= explanation: - when hydraulic pump is off it shut off the high and low pressure lines= too - opening the free fall valve create a short way of the two chambers of= the hydraulic actuator - problem is: the chamber capacity of the retracting is smaller than the= extending caused by the piston rod - hydraulic fluid is almoust incompressible - now free fall of gear - this cause a vacuum in the pusing sinde of the actuator (too less fluid= for chamber) - the lowering gear has to work against this vacuum - the vacuum gradually disapear because of air leakage through the o-ring= s You can do the opposite test: - when gear is down and locked - open the free fall valve - now try to push in the gear -> you won=C2=B4t be able to do so because now you are working against th= e (incombressibel) hydraulic fluid! Typical design error ... ;-( Johannes D-ESWS LNC2 ____________________________________ Von: Dominic V. Crain [mailto:domcrain@tpg.com.au] Gesendet: Mittwoch, 15. April 2009 13:51 An: lml@lancaironline.net Betreff: Gear Free Fall I=E2=80=99d like to draw on the opinion of listers regarding LNC2 gear fr= ee fall problem. The main gear is slow to free fall, and on the jacks (most likely in the= air) the RMG won=E2=80=99t lock in. Slight pressure on the wheel locks it in, which is handy if one wing walk= s upside down. Disconnected the actuator strut and it drops like a beauty and snaps into= position. I doubt the actuator struts are the problem because both main gear have= exhibited the same problem at the same time. The LMG does eventually lock= down on the jacks. One thing I=E2=80=99ve noticed is the NG is slower to lock down under nor= mal extension than it usually does. Until recently, it was always the first,= and quick to lock down. Under free fall the gas strut dives the NG down and= locks as it should quite quickly. Wondered if anyone might have a trouble shooting sequence I can draw upon= . Thanks Dom Crain VH-CZJ **************Great deals on Dell=E2=80=99s most popular laptops =E2=80=93= Starting at $479 (http://pr.atwola.com/promoclk/100126575x1220029082x1201385915/aol?redir= =3Dhttp:%2F%2Fad.doubleclick.net%2Fclk%3B213969145%3B35701480%3Bh) -------------------------------1239928917 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
Johannes,
 
I have never had the condition you mention happen to me.  In my= system there has always been a path back to the pump reservoir, thru the pump valves.
 
Scott Krueger
 
In a message dated 4/16/2009 1:59:18 P.M. Central Daylight Time, jschredl@web.de writes:
Dom,
 
I can confirm your observations!<= /DIV>
Many years ago I dicussed this subject with NEI= CO and gave them following explanation:
- when hydraulic pump is off it shut off the hi= gh and low pressure lines too
- opening the free fall valve create a short wa= y of the two chambers of the hydraulic actuator
- problem is: the chamber capacity of the retra= cting is smaller than the extending caused by the piston rod
- hydraulic fluid is almoust incompressible
- now free fall of gear
- this cause a vacuum in the pusing sinde of th= e actuator (too less fluid for chamber) 
- the lowering gear has to work against th= is vacuum
- the vacuum gradually disapear because of= air leakage through the o-rings
 
You can  do the opposite test:
- when gear is down and locked
- open the free fall valve
- now try to push in the gear
-> you won=C2=B4t be able to do so because= now you are working against the (incombressibel) hydraulic fluid!
 
Typical design error ... ;-(
 
Johannes
D-ESWS  LNC2
 
 

Von: Dominic V. Crain [mailto:domcrain@tpg.com.au]
Gesendet: Mittwoch, 15. April 20= 09 13:51
An: lml@lancaironline.net
Betreff: Gear Free= Fall

I=E2=80=99d like to= draw on the opinion of listers regarding LNC2 gear free fall problem.

The main gear is sl= ow to free fall, and on the jacks (most likely in the air) the RMG won=E2=80=99t lo= ck in.

Slight pressure on= the wheel locks it in, which is handy if one wing walks upside down.

Disconnected the ac= tuator strut and it drops like a beauty and snaps into position.

I doubt the actuato= r struts are the problem because both main gear have exhibited the same problem= at the same time. The LMG does eventually lock down on the jacks.

One thing I=E2=80= =99ve noticed is the NG is slower to lock down under normal extension than it usually does.= Until recently, it was always the first, and quick to lock down. Under free fa= ll the gas strut dives the NG down and locks as it should quite quickly.

Wondered if anyone= might have a trouble shooting sequence I can draw upon.

Thanks

Dom Crain

VH-CZJ


Great deals on Dell's most popular lap= tops - Starting at $479
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