Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Tue, 20 Jul 2004 09:49:39 -0400 Message-ID: X-Original-Return-Path: Received: from relay01.kbs.net.au ([203.220.32.149] verified) by logan.com (CommuniGate Pro SMTP 4.2b8) with ESMTP id 327360 for lml@lancaironline.net; Tue, 20 Jul 2004 06:08:35 -0400 Received-SPF: error receiver=logan.com; client-ip=203.220.32.149; envelope-from=goconnell@dodo.com.au Received: from [203.220.32.145] (helo=mail.kbs.net.au) by relay01.kbs.net.au with esmtp (Exim 3.36 #2) id 1BmrWy-0004Ns-00 for lml@lancaironline.net; Tue, 20 Jul 2004 20:07:28 +1000 Received: from [192.168.3.72] (helo=DodoInternetWebmailServer) by mail.kbs.net.au with smtp (Exim 3.36 #6) id 1BmrWu-0005jB-00 for lml@lancaironline.net; Tue, 20 Jul 2004 20:07:24 +1000 Received: from client 203.220.142.245 for UebiMiau2.7 (webmail client); Tue, 20 Jul 2004 20:07:24 +1000 X-Original-Date: Tue, 20 Jul 2004 20:07:24 +1000 From: "Gerard O Connell" X-Original-To: "Lancair Mailing List" Reply-to: "Gerard O Connell" Subject: Re: [LML] 320 hydraulics - 1989 kit X-Priority: 3 X-Mailer: Dodo Internet Webmail Server X-Original-IP: 203.220.142.245 Content-Transfer-Encoding: 8bit X-MSMail-Priority: Medium Importance: Medium Content-Type: text/html; charset="iso-8859-1"; MIME-Version: 1.0 X-Original-Message-Id: G'day George,

My LNC2 kit is a similar vintage to yours. VH-LPD

Yours is not an uncommon problem experienced by Lancair 320 owners. I purchased my LNC2 pre loved (am not a builder, just a flyer) and was aware of a leak in the hydraulic system which the mechanics who inspected the aircraft prior to purchase assuered me was internal and by upgrading to the outback gear would surely be solved. The symptom was a quick cycle of the gear motor every 30 secs or so on the ground.

So I upgraded the gear and had the flap mod performed. Guess what..still burped frequently when in the down and locked position (every 10-15 seconds) and less frequently in flight (every 15 mins or so).
Next step, order seal kits and replace all the seals. Still no solution. I also replaced the low pressure switch (not Lancair issue). This provided a temporary solution but the problem returned, only worse. This time it sounded like popcorn going off in the back!

I also then encountered the "select gear down and nothing happens" problem (also quite common)..moving the dump lever slightly causes the motor to cycle and the gear comes down. The diagnosis was a possible leak from high to low pressure across the dump valve. I then replaced the dump valve. Still no solution. Adjusted pressure setting to <550psi in low pressure switch. Cycling stopped but then gear unsafe light came on when taxying. That wasn't such a good idea.

I also replaced the valve assembly (under the trim motor) as there was an internal leak here which was causing pressure in the down side during gear retraction..the symptom was a nose gear door which closed in three jerky movements as pressure gradually bled back into the reservoir from the low side.

Finally I had the electrical circuits re-wired in accordance with original Lancair wiring diagram (someone had stuffed with it) and replaced both pressure switches with Lancair parts (the previous mechanic used automotive switches which were not compatible with aircraft hydraulic oil and thus providied only a temporary fix).
Guess what--problem solved--no more cycling except intermittent when up and locked--I can live with that.
An additional problem I had while resolving the hydraulic issues was a strange "buzzing" and mild vibration above 140kts IAS..this appears to have been related to a nose gear door not fully closing. This is also solved (I think).

Hope this information is of some value..am sure you don't have all of the problems I had !

Regards

Gerard

--------- Original Message --------
From: "Lancair Mailing List" <lml@lancaironline.net>
To: "Lancair Mailing List" <lml@lancaironline.net>
Subject: [LML] 320 hydraulics - 1989 kit
Date: 20/07/04 00:10

To anyone who has had this problem or knows of the solution:

A couple months ago my hydraulic pump began cycling often, like every 15 to
20 seconds for a brief half second burst, in cruise at altitude, i.e. 85 or
9500 ft. It seemed to be altitude related, that is, the pump would begin
cycling as I climbed above about 6000 ft. Previously, it would never cycle
even over an hour or more leg.

1. I ordered from Lancair, and installed, a new dump/bypass valve. The
symptoms/cycling continued.

2. I ordered and installed a new high pressure hydraulic switch. The pump
cycling continued.

There are no leaks, the reservoir is full. There has never been any cycling
on the down side.

Today, on another flight to get it to do something, it did something. At
9500 ft. in cruise, the short bursts of pump cycling got more frequent, then
the pump started running for longer periods of time, then it came on and
just continued running. I listened and watched and after about 20 to 30
seconds pulled the circuit breakers (pump and relays). The gear did not
drop out of the wheelwells. I descended and prior to landing, put the gear
switch down then pushed in the relay and pump CB's. The gear came down
normally, three green, the pump turned off and did not cycle at all all the
way in to shutdown.

I'll get it up on jacks and try to sort it out. But in the meantime, can a
hydraulic guru tell me if this problem is internal to the pump maybe? Do I
need to replace the pump? If one of the actuator seals is shot the pump
would cycle on the down side, right? Also, if an actuator seal is blown,
the gear would fall out of the wheelwells with the CB's pulled, right?

So, what is going on here?

George Shattuck
N320GS

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