LNC2 Gear pump

Submitted by Anonymous on

Forums: 

From: Greenbacks, UnLtd. <n4zq [at] verizon.net>
Subject: LNC2 Gear pump
Date: Wed, 06 Aug 2014 12:12:58 -0400
To: List Lancair Mailing <lml [at] lancaironline.net>

Well, my return flight from KBTV this morning ended on a bit of a sour note. About 30 minutes out, I began hearing the occasional single click behind me and it turned out to be the hi pressure gear relay.

The gear in transit light would come on for a very, very brief moment as the pressure dropped to about 970psi. About 30seconds later the process would repeat.

So the system does not want to hold high pressure. I’m heading back to the hangar in a bit to download data from the last few flights as well as to check for any fluid leaks.



Bummer…



Angier Ames

N4ZQ

LNC2 Gear Pump

Submitted by Anonymous on

From: Greenbacks, UnLtd. <n4zq [at] verizon.net>
Subject: LNC2 Gear Pump
Date: Thu, 07 Aug 2014 19:07:48 -0400
To: List Lancair Mailing <lml [at] lancaironline.net>
Message Header


Undecoded Message

Hey guys, I have attached an excel spreadsheet showing the hydraulic pressure data for nine flights from March 5, 2013 through August 6, 2014.

The data for the first 6 flights seem fairly typical, and I would expect minor changes due to altitude/temperature differences.

The flight on July 11th for example had the gear coming up at 7:21:12am with the pump shutting off at 1440psi. and slowly dropping to 1080psi at 7500ft

where Bill Harrelson aka Wineaux and I conducted a first GAMI lean exercise. Not sure why some residual pressure seems to remain on the low side.

Perhaps one of you can shed light on this.

The first indication of any irregularity occurred on the 7/31 flight at 9:49:09am when the pressure had dropped to 850 and the pump came on. The on cycles were momentary

for the remainder of the flight but came with greater frequency.

For the last flight on 8/6, the gear came up with the pump shutting off at 1470psi and I climbed to 2500ft, pressure immediately began to drop and the pump cycled again at 860psi

and the recycle events came with greater frequency.



So at this point, there is no evidence of any external fluid leaks. I’m thinking there may an internal leak in one of the six actuators, an issue with the pump itself, or possibly….

a failing high pressure limit switch.



Any comments and advice from all you hydraulic wizards is gratefully appreciated.



Thanks,



Angier Ames

N4ZQlml



This file only contains the last three flights due to the size of the original not being accepted on LML.

The complete file is posted to Lancairtalk.net.

LNC2 Gear Pump

Submitted by Anonymous on

From: Greenbacks, UnLtd. <n4zq [at] verizon.net>
Subject: Re: LNC2 Gear Pump
Date: Thu, 07 Aug 2014 20:28:21 -0400
To: John Cooper <snopercod [at] comporium.net>
Cc: List Lancair Mailing <lml [at] lancaironline.net>
Message Header


Undecoded Message

Hey, thanks for your response.

Which flight date are you looking at?

Your test gauge offer is much appreciated, does it monitor both HI and LO sides or do you switch from one side to the other?

I put 4ZQ up on jacks this morning and raised the gear. HI pressure immediately started to bleed off but it was interesting to note

that the gear stayed tucked up nicely until the pressure had dropped to 310psi. At this pressure, the gear doors had begun to open by about .125”.



Angier Ames



I’m at 250 Cutler Road

South Hamilton, MA. 01982





On Aug 7, 2014, at 8:08 PM, John Cooper <snopercod [at] comporium.net> wrote:



> Angier--

>

> I'm no "wizard", but In looking at that data, everything seemed to be just fine until 9:31:45 when the LO pressure spiked up to 1220 and then bled off. A few seconds later, at 9:31:54, apparently you put the gear up since the high pressure went up to 1490 then started a slow decay for 17 minutes until 9:49:12, Whatever happened, it got worse from then on. Maybe you can relate those times to anything you might have been doing at those times?

>

> I don't think it matters, though; I'm guessing you have an internal leak somewhere. OTOH, The high-pressure switch kept starting the pump at ~850 (sounds right to me)  and shutting it off at ~1050 (seems a little low). So the pressure switch was doing its job.

>

> What happened between 10:58:26 and 10:58:32 when there was little pressure on either side? Was the dump valve open for 6 seconds or was that just a transition from Gear Down to Gear Up? If the latter, it seems kind of long...

>

> I'm assuming that your pump is the newer model with the back pressure circuit?

>

> Bottom line: If I were in your situation, I would isolate the pump and check the pressures. I'd be glad to mail you my test gauge if you'd like.

>

> Best--

>

> --John

>



LNC2 Gear Pump

Submitted by Anonymous on

From: Gary Edwards <gary21sn [at] hotmail.com>
Sender: <marv [at] lancaironline.net>
Subject: Re: LNC2 Gear Pump
Date: Fri, 08 Aug 2014 07:52:22 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message
Or the ball pressure dump value between high & low lines is
leaking.
 
Gary
-----
Original Message -----
To:
lml [at] lancaironline.net (Lancair Mailing List)

Sent:
Thursday, August 7, 2014 4:07 PM
Subject:
[LML] LNC2 Gear Pump

Hey guys, I have attached an excel spreadsheet showing the
hydraulic pressure data for nine flights from March 5, 2013 through August 6,
2014.
The data for the first 6 flights seem fairly typical, and I would
expect minor changes due to altitude/temperature differences.
The flight on
July 11th for example had the gear coming up at 7:21:12am with the pump
shutting off at 1440psi. and slowly dropping to 1080psi at 7500ft
where
Bill Harrelson aka Wineaux and I conducted a first GAMI lean exercise. Not
sure why some residual pressure seems to remain on the low side.
Perhaps
one of you can shed light on this.
The first indication of any irregularity
occurred on the 7/31 flight at 9:49:09am when the pressure had dropped to 850
and the pump came on. The on cycles were momentary
for the remainder of the
flight but came with greater frequency.
For the last flight on 8/6, the
gear came up with the pump shutting off at 1470psi and I climbed to 2500ft,
pressure immediately began to drop and the pump cycled again at 860psi
and
the recycle events came with greater frequency.

So at this point, there
is no evidence of any external fluid leaks. I’m thinking there may an internal
leak in one of the six actuators, an issue with the pump itself, or
possibly….
a failing high pressure limit switch.

Any comments and
advice from all you hydraulic wizards is gratefully
appreciated.

Thanks,

Angier Ames
N4ZQlml

This file
only contains the last three flights due to the size of the original not being
accepted on LML.
The complete file is posted to
Lancairtalk.net.

LNC2 Gear Pump

Submitted by Anonymous on

From: Chris Zavatston <chris_zavatson [at] yahoo.com>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] LNC2 Gear Pump
Date: Fri, 08 Aug 2014 07:52:36 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

Angier,

It looks like it is time to start isolating circuits and then actuators.  If it is a cylinder, don't forget about the sealing washer under the piston nut.

Chris



Sent from my spiffy iPhone



On Aug 7, 2014, at 4:07 PM, "Greenbacks, UnLtd." <n4zq [at] verizon.net> wrote:



> Hey guys, I have attached an excel spreadsheet showing the hydraulic pressure data for nine flights from March 5, 2013 through August 6, 2014.

> The data for the first 6 flights seem fairly typical, and I would expect minor changes due to altitude/temperature differences.

> The flight on July 11th for example had the gear coming up at 7:21:12am with the pump shutting off at 1440psi. and slowly dropping to 1080psi at 7500ft

> where Bill Harrelson aka Wineaux and I conducted a first GAMI lean exercise. Not sure why some residual pressure seems to remain on the low side.

> Perhaps one of you can shed light on this.

> The first indication of any irregularity occurred on the 7/31 flight at 9:49:09am when the pressure had dropped to 850 and the pump came on. The on cycles were momentary

> for the remainder of the flight but came with greater frequency.

> For the last flight on 8/6, the gear came up with the pump shutting off at 1470psi and I climbed to 2500ft, pressure immediately began to drop and the pump cycled again at 860psi

> and the recycle events came with greater frequency.

>

> So at this point, there is no evidence of any external fluid leaks. I’m thinking there may an internal leak in one of the six actuators, an issue with the pump itself, or possibly….

> a failing high pressure limit switch.

>

> Any comments and advice from all you hydraulic wizards is gratefully appreciated.

>

> Thanks,

>

> Angier Ames

> N4ZQlml

>

> This file only contains the last three flights due to the size of the original not being accepted on LML.

> The complete file is posted to Lancairtalk.net.

>

> <new data.xlsx>

> --

> For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html

LNC2 Gear Pump

Submitted by Anonymous on

From: Greenbacks, UnLtd. <n4zq [at] verizon.net>
Subject: LNC2 Gear Pump
Date: Fri, 08 Aug 2014 20:46:08 -0400
To: List Lancair Mailing <lml [at] lancaironline.net>
Cc: Chris Zavatston <chris_zavatson [at] yahoo.com>
Message Header


Undecoded Message

Hi Chris,





You said.."It looks like it is time to start isolating circuits and then actuators.  Agreed





I’m not sure what you mean by this.



If it is a cylinder, don't forget about the sealing washer under the piston nut.”



OK, hear’s a dumb question for you….



I have no external leaks so, if there is an internal leak in one of the actuators(I mean cylinders for gear and doors, , and as the high pressure begins to drop, should we not see a corresponding

increase in pressure on the low side?



As for the dump valve, I trashed that which came with the kit in favor of higher quality. I don’t think I have a dump valve issue.



Hoping this does not screw up my plans for KRDM.





Angier

N4ZQ

LNC2 Gear Pump

Submitted by Anonymous on

From: Chris Zavatston <chris_zavatson [at] yahoo.com>
Sender: <marv [at] lancaironline.net>
Subject: Re: [LML] LNC2 Gear Pump
Date: Sun, 10 Aug 2014 08:47:24 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message
and as the high pressure begins to drop, should we not see a corresponding
increase in pressure on the low side?

Angier,
Take a look at figure 9 in the link.  
If you go to the cylinder you'll be able to follow the low side of the piston all the way back to the reservoir. You might see ~100 psi from the reservoir back pressure spring but that is it.  Pressure does not build beyond that.


As for the sealing washer, "reassembly" on page 8 has some good pics.

Only once have I had a sudden large leak. It was the sealing washer that split under the nut.
Chris

Sent from my spiffy iPhone

On Aug 8, 2014, at 5:46 PM, "Greenbacks, UnLtd." <n4zq [at] verizon.net

> wrote:

Hi Chris,


You said.."It looks like it is time to start isolating circuits and then actuators.  Agreed


I’m not sure what you mean by this.

If it is a cylinder, don't forget about the sealing washer under the piston nut.”

OK, hear’s a dumb question for you….

I have no external leaks so, if there is an internal leak in one of the actuators(I mean cylinders for gear and doors, , and as the high pressure begins to drop, should we not see a corresponding
increase in pressure on the low side?

As for the dump valve, I trashed that which came with the kit in favor of higher quality. I don’t think I have a dump valve issue.

Hoping this does not screw up my plans for KRDM.


Angier
N4ZQ




--
For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html

LNC2 Gear Pump

Submitted by Anonymous on

From: Greenbacks, UnLtd. <n4zq [at] verizon.net>
Subject: Re: LNC2 Gear Pump
Date: Mon, 11 Aug 2014 09:25:52 -0400
To: List Lancair Mailing <lml [at] lancaironline.net>
Cc: Chris Zavatston <chris_zavatson [at] yahoo.com>, John Cooper <snopercod [at] comporium.net>
Message Header


Undecoded Message

Chris,



Are the replacement seal kits for our gear and door cylinders available

from typical hydraulic sources? I can’t find anything on the Lancair/Kit Components site.



Thanks,



Angier

LNC2 Gear Pump

Submitted by Anonymous on

From: Danny <danny [at] n107sd.com>
Sender: <marv [at] lancaironline.net>
Subject: RE: [LML] Re: LNC2 Gear Pump
Date: Tue, 12 Aug 2014 07:20:23 -0400
To: <lml [at] lancaironline.net>
Message Header


Undecoded Message

You should be able to get them from any Parker store but you have to know

what to get.  Search Kit Components for CYLINDER HYDRAULIC REBUILD KIT.  The

have them.



Danny

LNC2-360 Mk-II

AOPA 04856278

EAA 647062

NRA 156453324

Nothing is foolproof to the sufficiently talented fool.



-----Original Message-----

From: Greenbacks, UnLtd. [n4zq [at] verizon.net (mailto:)

]

Sent: Monday, August 11, 2014 9:26 AM

To: Lancair Mailing List

Subject: [LML] Re: LNC2 Gear Pump



Chris,



Are the replacement seal kits for our gear and door cylinders available from

typical hydraulic sources? I can't find anything on the Lancair/Kit

Components site.



Thanks,



Angier







--

For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html

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