X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 23 Apr 2012 12:05:17 -0400 Message-ID: X-Original-Return-Path: Received: from mail-ob0-f180.google.com ([209.85.214.180] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTPS id 5501542 for lml@lancaironline.net; Mon, 23 Apr 2012 05:59:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.180; envelope-from=pjdmiller@gmail.com Received: by obbwc20 with SMTP id wc20so12509382obb.25 for ; Mon, 23 Apr 2012 02:58:39 -0700 (PDT) Received: by 10.182.155.35 with SMTP id vt3mr3279218obb.63.1335175119461; Mon, 23 Apr 2012 02:58:39 -0700 (PDT) X-Original-Return-Path: Received: from [10.162.201.177] (mobile-166-147-065-038.mycingular.net. [166.147.65.38]) by mx.google.com with ESMTPS id s8sm12467058oec.1.2012.04.23.02.58.37 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 23 Apr 2012 02:58:38 -0700 (PDT) Subject: Re: [LML] Re: Excessive down hydraulic pressure References: From: Paul Miller Content-Type: multipart/alternative; boundary=Apple-Mail-2-385630412 X-Mailer: iPad Mail (8L1) In-Reply-To: X-Original-Message-Id: <5FAC91CA-4D34-47E7-9B41-8270F661F876@gmail.com> X-Original-Date: Mon, 23 Apr 2012 04:58:01 -0500 X-Original-To: Lancair Mailing List Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (iPad Mail 8L1) --Apple-Mail-2-385630412 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Something doesn't make sense Adam. If there is no restriction then the Dow= n pressure and any size cylinder should easily close the inner door even wit= h the spring and you have removed the spring. Why isn't that door slamming= shut with 600 psi? Paul On 2012-04-22, at 23:53, Adam Molny wrote: > Chris =E2=80=93 > =20 > The pump p/n is 108AM19-CLB-3VT, manufacture date 11/00. I did change to t= he higher capacity pump, so the =E2=80=9819=E2=80=99 part of the number is n= o longer correct. > =20 > Regarding uncharted territory, you can take a look at the hydraulic schema= tic here. The only difference from the stock system it that the fluid flow t= o the doors is reversed during certain phases of operation. As with any long= -duration build, there could be age related issues involved (the pump=E2=80=99= s age, not mine!). The next step will be to disassemble the pump to see if t= here=E2=80=99s anything suspicious in there (such as a reversed spool valve o= r deteriorated o-rings). > =20 > -Adam Molny > Still test flying, 10.0hrs on the Hobbs > From: Chris Zavatston [mailto:chris_zavatson@yahoo.com]=20 > Sent: Wednesday, April 18, 2012 3:35 PM > To: lml@lancaironline.net > Subject: Re: [LML] Re: Excessive down hydraulic pressure > =20 > Adam, > Wow, I looks like you are venturing into some uncharted territory - both i= n design and now troubleshooting. Your hydraulic schematic is the place to s= tart. > The recorded time history of pressure is a really neat tool to have. > =20 > Chris Zavatson > N91CZ > 360std > www.N91CZ.net >=20 >=20 >=20 > On Apr 18, 2012, at 10:01 AM, Adam Molny wro= te: >=20 >> Hi Jeff =E2=80=93 >> =20 >> Yes, I=E2=80=99m using my Sequenced Gear System in this plane. The inner g= ear doors close after the landing gear is extended for landing. I can say fr= om experience that it provides a huge reduction in wind noise and cockpit dr= afts. Naturally I investigated whether my system could be contributing to th= e problem. During system development I changed to a down pressure switch wit= h a set point of 650psi. The stock 550psi switch didn=E2=80=99t provide enou= gh =E2=80=98oomph=E2=80=99 to close the inner gear doors against the emergen= cy opening springs. I have an older kit with the narrow diameter door cylind= ers. Customers with the newer style large-diameter cylinders are able to use= the stock pressure switch. >> =20 >> Theoretically, having a down pressure with a higher set point should help= alleviate this problem since the system would be less sensitive to pressure= buildup on the down side. I believe we can also rule out pressure buildup d= ue to thermal expansion. My early flights never went above 5000=E2=80=99 so t= here wasn=E2=80=99t a big temperature swing. Also, you would expect to see a= gradual rise in pressure due to cold soaking, which wasn=E2=80=99t the case= . >> =20 >> Partway through the build process I also modified my hydraulic pump by in= stalling the high capacity impeller. >> =20 >> As part of the troubleshooting process I have removed the inner gear door= springs. The gear still extend quickly in both ground and flight tests as s= een in my fourth flight video. http://www.youtube.com/watch?v=3Dfo1qnhBuqS8.= While developing the sequenced gear system I learned that the pressure swit= ches can be wildly inaccurate, and they behave oddly at the limits of their a= djustment range. As you turn the adjusting screw to increase the pressure th= e hysteresis decreases. In other words, the pressure difference between turn= ing off and turning back on again gets smaller. This can lead to pump chatte= r where the gear hit their stops, the pressure rises and the pump shuts off.= Then the pressure drops slightly and the pump kicks in again. This can happ= en several times per second and last several seconds. The solution was to ma= ke sure the adjustable pressure switch was set near the middle of its pressu= re range. >> =20 >> I don=E2=80=99t have a solution yet but I=E2=80=99m reading through Chris= Zavatson=E2=80=99s excellent write up on the Lancair hydraulic system http:= //www.n91cz.com/Hydraulics/Lancair%20Hydraulics.pdf. I=E2=80=99m beginning t= o suspect a sticky shuttle valve or some other internal pump problem, with t= he pressure switches as a secondary suspect. On my fifth flight yesterday I h= ad to crack the dump valve to get the doors to close completely with the gea= r retracted =E2=80=93 and this was with the door springs removed! >> =20 >> -Adam Molny >> 7.6hrs Hobbs time and counting >> From: Jeffrey W. Skiba [mailto:jskiba@icosa.net]=20 >> Sent: Tuesday, April 17, 2012 9:52 AM >> To: lml@lancaironline.net >> Subject: RE: [LML] Excessive down hydraulic pressure >> =20 >> Adam, >> =20 >> Are you running the Stock Lancair gear system or are you using your gear s= ystem ? >> =20 >> Do you have the first generation pump or the high capacity one ? > =3D --Apple-Mail-2-385630412 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
Something doesn't make sense Adam. &nbs= p; If there is no restriction then the Down pressure and any size cylinder s= hould easily close the inner door even with the spring and you have removed t= he spring.   Why isn't that door slamming shut with 600 psi?
=
Paul

On 2012-04-22, at 23:53, Adam Molny <Adam@ValidationPartners.com> wrote:=

Chris =E2=80=93

 

The pump p/n is 108AM19-CLB-3VT, manufacture date 11/00. I did change to the higher capacity pump, so the =E2= =80=9819=E2=80=99 part of the number is no longer correct.

 

Regarding uncharted territory, you can take a look at the hydraulic schematic here. The only difference from the stock system it that the fluid flow to the doors is reve= rsed during certain phases of operation. As with any long-duration build, there could be age related issues involved (the pump=E2=80=99s age, not mine!). Th= e next step will be to disassemble the pump to see if there=E2=80=99s anything= suspicious in there (such as a reversed spool valve or deteriorated o-rings)= .

 

-Adam Molny

Still test flying, 10.0hrs on the Hobbs<= /font>

From: Chris Z= avatston [mailto:chris_zavatson@yahoo.com]
Sent: Wednesday, April 18, 20= 12 3:35 PM
To: lml@lancaironline.n= et
Subject: Re: [LML] Re: Excess= ive down hydraulic pressure

 

Adam,

Wow, I looks like you are venturing into some uncharted territory - both in design and now troubleshooting.  Your hydraulic schematic is th= e place to start.

The recorded time history of pressure is a really neat tool to have.=

 

Chris Zavatson

N91CZ

360std


On Apr 18, 2012, at 10:01 AM, Adam Molny <Adam@Validati= onPartners.com> wrote:

Hi Jeff =E2=80=93

 <= /o:p>

Yes, I=E2=80=99m using my Sequenced Gea= r System in this plane. The inner gear doors close after the landing gear is extended for landing. I can say from experience that it provides a huge reduction in wind noise and cockpit drafts. Naturally I investigated whether= my system could be contributing to the problem. During system development I changed to a down pressure switch with a set point of 650psi. The stock 550p= si switch didn=E2=80=99t provide enough =E2=80=98oomph=E2=80=99 to close the in= ner gear doors against the emergency opening springs. I have an older kit with the narrow diameter door cylinders. Customers with the newer style large-diamete= r cylinders are able to use the stock pressure switch.

 <= /o:p>

Theoretically, having a down pressure w= ith a higher set point should help alleviate this problem since the system would= be less sensitive to pressure buildup on the down side. I believe we can also r= ule out pressure buildup due to thermal expansion. My early flights never went above 5000=E2=80=99 so there wasn=E2=80=99t a big temperature swing. Also, y= ou would expect to see a gradual rise in pressure due to cold soaking, which wasn=E2=80=99t the case.

 <= /o:p>

Partway through the build process I als= o modified my hydraulic pump by installing the high capacity impeller.

 <= /o:p>

As part of the troubleshooting process I= have removed the inner gear door springs. The gear still extend quickly in b= oth ground and flight tests as seen in my fourth flight video.&nbs= p;http://www.youtube.com/watch?v=3Dfo1qnhBuqS8= . While developing the sequenced gear system I learned that t= he pressure switches can be wildly inaccurate, and they behave oddly at the lim= its of their adjustment range. As you turn the adjusting screw to increase the pressure the hysteresis decreases. In other words, the pressure difference between turning off and turning back on again gets smaller. This can lead to= pump chatter where the gear hit their stops, the pressure rises and the pump= shuts off. Then the pressure drops slightly and the pump kicks in again. Thi= s can happen several times per second and last several seconds. The solution w= as to make sure the adjustable pressure switch was set near the middle of its p= ressure range.

 <= /o:p>

I don=E2=80=99t have a solution yet but= I=E2=80=99m reading through Chris Zavatson=E2=80=99s excellent write up on t= he Lancair hydraulic system http://www.n91cz.com/Hydraulics/Lancair%20Hydraulic= s.pdf. I=E2=80=99m beginning to suspect a sticky shuttle valve or= some other internal pump problem, with the pressure switches as a secondary suspe= ct. On my fifth flight yesterday I had to crack the dump valve to get the doors t= o close completely with the gear retracted =E2=80=93 and this was with the doo= r springs removed!

 <= /o:p>

-Adam Molny<= o:p>

7.6hrs Hobbs time and counting

From: Jeffre= y W. Skiba [mailto:jskiba@icosa.net]
Sent: Tuesday, April 17, 2012= 9:52 AM
To: lml@lancaironline.n= et
Subject: RE: [LML] Excessive d= own hydraulic pressure

 

<= span style=3D"font-size:11.0pt;font-family:Calibri;color:#1F497D">Adam,

<= span style=3D"font-size:11.0pt;font-family:Calibri;color:#1F497D">&nbs= p;

<= span style=3D"font-size:11.0pt;font-family:Calibri;color:#1F497D">Are you ru= nning the Stock Lancair gear system or are you using your gear system ?

<= span style=3D"font-size:11.0pt;font-family:Calibri;color:#1F497D">&nbs= p;

<= span style=3D"font-size:11.0pt;font-family:Calibri;color:#1F497D">Do you hav= e the first generation pump or the high capacity one ?<= o:p>

=3D
= --Apple-Mail-2-385630412--