Mailing List lml@lancaironline.net Message #57494
From: Wolfgang <Wolfgang@MiCom.net>
Sender: <marv@lancaironline.net>
Subject: Re: Lancair 320/360 hydraulic system questions and fixes
Date: Thu, 10 Feb 2011 12:04:35 -0500
To: <lml@lancaironline.net>
You have a couple of things to look at.
 
First, make sure that your cylinders have hard stops and free range of movement so you don't bend or break any more cylinders.
 
Second, get the plane up on jacks and check that the pump is operating propperly and delivering fluid at pressure to properly actuate the gear. If I recall, the pump has a safety dump internally set at about 3000 psi so your plumbing has to handle at least that kind of pressure.
 
The pump is usually a 108AM series which means it will draw up to about 70 amps at 12 volts but normally 45 amps if everything is working optimally.
The high flow pump can pull up to 90 amps at 12 volts but normally 60 amps if everything is working optimally.
That means minimum #6 or even #4 wire from the main disconnect to the pump.
This puts a heavy load on the control relays let alone the electrical system. The 108AE (permanent magnet motor) pump can cut that 70 amps to about 50.
 
Then you may want to look at the pump control wiring to suppress electrical transients to quiet down the system and make the contacts last longer. See attachment.
Be careful about the recent talk about "new technology" relays and make sure their contacts can handle the pump current.
 
Wolfgang
 
----- Original Message -----
From: Roy Space
Sent: Thursday, February 10, 2011 9:30 AM
Subject: RE: Lancair 320/360 hydraulic system questions and fixes

Wolfgang,

My first email was short because I did not know if you would get it or not. Thanks for the reply. People like you keep dummies like me flying.

 

Here is my situation:

 

Lancair N320RS first flew Feb 1 2010. Now at 82 hrs. Pressure gauges on gear up and gear down. Pressures always high at about 1500 and 1000 psi. Often after sitting a few days pump would run as soon as master was activated. Pump would go clack- clack- clack from one to many times then stop. Very noisy never smooth like pumps I have used in industry before. I asked a mechanic to look at it and he said it was fine (don’t think so). Original pump, exact model unknown but kit was started in 1988! Yes that is correct, long story, moves, slow work, money, etc.

 

Have had some problems with micro monitor after takeoff and now suspect the hydraulic pump as in Scott Krueger’s article that is at http://www.mail-archive.com/lancair.list@olsusa.com/msg09420.html

 

On last flight, lost micro monitor and took long time to get transition light off. Was first time in cold flying, normally fly out of Houston, moved to Colorado. On landing green lights were slow to come on. Let set for a couple of weeks, pressure gauges both read zero, master on and pump runs real smooth and quiet but does not build pressure. I had to leave for Houston and did not get to check any further. Now in Houston, returning to Colorado next week and looking for answers. Only previous gear problem was at 2 hrs TT one gear retract cylinder failed in the down position, threaded end bent at the end of the threads and broke off, shaft bend in a bow and ruined, found during preflight and no problem, gear would not have retracted on take off.

 

I liked your article and never did like the one pressure point activation. Your module sounds good even if just for a better system.

 

What do you think?

Roy Space

 

 

 

From: Wolfgang [mailto:Wolfgang@MiCom.net]
Sent: Wednesday, February 09, 2011 4:43 PM
To: Roy Space
Subject: Re: Lancair 320/360 hydraulic system questions and fixes

 

Which problem is that ? I'm not sure I understand your question.

I have developed a module to address the overpressure malfunction in the 320/360 hydraulic system if that's what you mean.

If you're refering to the "noise" caused by switch contacts going bad, that's a simple one as I indicated on the list.

 

Wolfgang

 

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

From: Roy Space

Sent: Wednesday, February 09, 2011 5:27 PM

Subject: Lancair 320/360 hydraulic system questions and fixes

 

I have the same problem. Did you ever make the electrical fix?

I am interested.

 

Roy Space

N320RS

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