X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from omr-d01.mx.aol.com ([205.188.252.208] verified) by logan.com (CommuniGate Pro SMTP 6.0.5) with ESMTPS id 6353966 for lml@lancaironline.net; Fri, 28 Jun 2013 15:00:27 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.252.208; envelope-from=Sky2high@aol.com Received: from mtaomg-db05.r1000.mx.aol.com (mtaomg-db05.r1000.mx.aol.com [172.29.51.203]) by omr-d01.mx.aol.com (Outbound Mail Relay) with ESMTP id 05038700544FB for ; Fri, 28 Jun 2013 14:59:53 -0400 (EDT) Received: from core-mtd004b.r1000.mail.aol.com (core-mtd004.r1000.mail.aol.com [172.29.235.205]) by mtaomg-db05.r1000.mx.aol.com (OMAG/Core Interface) with ESMTP id D1CA2E000082 for ; Fri, 28 Jun 2013 14:59:52 -0400 (EDT) From: Sky2high@aol.com Full-name: Sky2high Message-ID: Date: Fri, 28 Jun 2013 14:59:52 -0400 (EDT) Subject: Re: [LML] Re: Fwd: Hydraulic pump cycling / Replacing dump valve To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_a6524.43e4c6c.3eff3728_boundary" X-Mailer: AOL 9.6 sub 168 X-Originating-IP: [67.175.156.123] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1372445992; bh=HdI8TfOHzS//+2pjYPMcE+BLQmwGyPrbpd49RUPotiE=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=pf+IY7EmzOmR4AdAr9U/T1ESsVWTCLhuxHbvHQv+ZerCTXs3Vg97OgMTR3HWkxJ3n 0GS8q51ykCTN4IwsGyaxlGFSt4WBsuZqvHBDJ1yMphH1bp2OqXJ/4KO8t51eCVB/yM C6YVGxSHRF0wfGqHcfMethpFNQqlFVrlszp+eBS0= X-AOL-SCOLL-SCORE: 0:2:399313632:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d33cb51cddd281e21 --part1_a6524.43e4c6c.3eff3728_boundary Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en Erik and Danny, =20 There are other ways to more quickly isolate the problem. If you suspect= =20 an actuator, first determine if the potential internal leak is on the up o= r=20 down side - that cuts the max number of tests in half. Consider that each= =20 gear has a door. So, a better place to cap off a pair is at the X=20 (actually shaped like a plus sign). This means a max of 2 tests would iso= late the=20 problem to a specific gear/door pair. Then one more test at one of the=20 actuators should isolate it to a specific actuator. =20 Yeah, it is a fun time...... =20 Grayhawk =20 =20 In a message dated 6/28/2013 1:34:34 P.M. Central Daylight Time, =20 danny@n107sd.com writes: =20 You=E2=80=99re about to embark on some real time consuming fun. If you ha= ve one=20 of the old dump valves, they were rated at only about 600 psi as I recall.= =20 The ball valve had a Teflon coating that would deform under high pressure= =20 and leak. You need a Parker valve rated at 2000 psi or higher. I believe= =20 mine is rated at 5000 psi. But, if your dump valve is that hard to get to= ,=20 maybe you want to check all your gear and door cylinders first. There are= =20 six of them so get a handful of AN fitting caps & plugs, jack up your plan= e=20 and have at it. I=E2=80=99d also suggest installing 2 hydraulic 3000 psi = pressure=20 gauges, one on the low pressure side, another on the high side. Cap &=20 plug all of the cylinders, isolate the valve from the pump and then run th= e =20 pump. If it cycles, the pump has an internal leak. If not, introduce the= =20 valve back into the system and run it again. If it cycles, your valve is= =20 bad. Then introduce one cylinder at a time, run the pump and see when it= =20 cycles. This all takes a lot of time but it=E2=80=99s the only way to fig= ure it out. =20 Happy hunting.=20 Danny=20 LNC2-360 Mk-II=20 Nothing is foolproof to the sufficiently talented fool.=20 From: Erik Larson [mailto:asw20747@aol.com]=20 Sent: Friday, June 28, 2013 9:32 AM To: lml@lancaironline.net Subject: [LML] Fwd: Hydraulic pump cycling / Replacing dump valve=20 =20 I have a Legacy, 6 1/2 years, appx 650 hours, we started experiencing=20 momentary hydraulic pump cycling, averaging now every 6-8 minutes for a mi= cro =20 second.=20 =20 =20 =20 There are NO external leaks and NO loss of fluid in the system, so I guess= =20 it's time to start trouble shooting to find the internal bypass. =20 Following some previous postings on the issue, it seems that if it's not t= he=20 cylinders, then the next logical place would be the dump valve. =20 =20 At first glance it looks like getting the dump valve changed out could be= =20 quite a job. Anyone that's done it recently care to share some Helpful =20 Hints? =20 =20 It looks like the only way to get to it, is by disassembling the throttle= =20 quadrant, even then it looks tight? =20 =20 Any advise on that or general trouble shooting advise for the hydraulic=20 system would be GREATLY appreciated! =20 =20 Erik Larson =20 Legacy/N74FX --part1_a6524.43e4c6c.3eff3728_boundary Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
Erik and Danny,
 
There are other ways to more quickly isolate the problem.&nb= sp;=20 If you suspect an actuator, first determine if the potential internal leak = is on=20 the up or down side - that cuts the max number of tests in half. = =20 Consider that each gear has a door. So, a better place to cap off a pair is= at=20 the X (actually shaped like a plus sign).  This means a max of 2 = tests=20 would isolate the problem to a specific gear/door pair.  Then one more= test=20 at one of the actuators should isolate it to a specific=20 actuator.
 
Yeah, it is a fun time......
 
Grayhawk
 
In a message dated 6/28/2013 1:34:34 P.M. Central Daylight Time,=20 danny@n107sd.com writes:
=

You=E2=80=99re about = to embark on some=20 real time consuming fun.  If you have one of the old dump valves, th= ey=20 were rated at only about 600 psi as I recall.  The ball valve had a= =20 Teflon coating that would deform under high pressure and leak.  You = need=20 a Parker valve rated at 2000 psi or higher.  I believe mine is rated= at=20 5000 psi.  But, if your dump valve is that hard to get to, maybe you= want=20 to check all your gear and door cylinders first.  There are six of t= hem=20 so get a handful of AN fitting caps & plugs, jack up your plane and h= ave=20 at it.  I=E2=80=99d also suggest installing 2 hydraulic 3000 psi pre= ssure gauges,=20 one on the low pressure side, another on the high side.  Cap & p= lug=20 all of the cylinders, isolate the valve from the pump and then run the=20 pump.  If it cycles, the pump has an internal leak.  If not,=20 introduce the valve back into the system and run it again.  If it cy= cles,=20 your valve is bad.  Then introduce one cylinder at a time, run the p= ump=20 and see when it cycles.  This all takes a lot of time but it=E2=80= =99s the only=20 way to figure it out.  Happy hunting.

 

Danny

LNC2-360=20 Mk-II

Nothing is foolproof = to the=20 sufficiently talented fool.

 

From: Erik Larso= n=20 [mailto:asw20747@aol.com]
Sent: Friday, June 28, 2013 9:32=20 AM
To: lml@lancaironline.net
Subject: [LML] Fwd: Hydr= aulic=20 pump cycling / Replacing dump valve

 

I=20 have a Legacy, 6 1/2 years, appx 650 hours, we started experiencing momen= tary=20 hydraulic pump cycling, averaging now every 6-8 minutes for a micro=20 second.

 

There are NO ex= ternal=20 leaks and NO loss of fluid in the system, so I guess it's time to start= =20 trouble shooting to find the internal bypass.  Following some previo= us=20 postings on the issue, it seems that if it's not the cylinders, then the = next=20 logical place would be the dump valve.

 

At first glance= it=20 looks like getting the dump valve changed out could be quite a job.=20  Anyone that's done it recently care to share some Helpful=20 Hints?

 

It looks like t= he only=20 way to get to it, is by disassembling the throttle quadrant, even then it= =20 looks tight?

 

Any advise on t= hat or=20 general trouble shooting advise for the hydraulic system would be=20 GREATLY appreciated!

 

Erik=20 Larson

Legacy/N74FX

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