REFLECTOR: Landing Gear Pump Not Holding Pressure

Carl Hoffman hoffman3 at rcn.com
Sun Jan 6 18:07:08 CST 2013


What? It must maintain pressure for down to make sure the nose gear goes over center. Also you need an emergency over ride in case the down pressure switch fails. If you lose electrical power you need a dump valve and a stick to shove thru a hole to lock the nose gear down. 
Only two things can cause what it happening, a cylinder O ring or a pressure switch, if you do not have an external leak or a faulty dump valve. 
It's possible the pump down check valve has failed, but these are usually "bullet proof".

Sent from my iPad 2.


On Jan 6, 2013, at 6:25 PM, Doug Kanczuzewski <doug at customstudio.com> wrote:

> When gear is down you should not have any pressure and pump would not run. It only runs to maintain pressure when up.
> 
> Doug
> 
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Darrell & Nora Kufalk
> Sent: Sunday, January 06, 2013 3:21 PM
> To: 'Velocity Aircraft Owners and Builders list'
> Subject: Re: REFLECTOR: Landing Gear Pump Not Holding Pressure
> 
> I didn't explain that very well.  The switches were still connected.  I capped the 2 lines going through canard bulkhead and I have the mechanical door actuator.  The switches are working correctly.  As soon as the pump stops, the pressure bleeds off somehow.
> 
> 
> 
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Carl Hoffman
> Sent: Sunday, January 06, 2013 3:53 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Landing Gear Pump Not Holding Pressure
> 
> Something is not making sense here. If both outlet tubes are capped off, where are the pressure switches that would cause the pump to cycle?
> One of the outlets is for the up side, and the other is for the down side.
> Maybe you just have a faulty down side pressure switch somewhere causing it.
> Over the past 12 1/2 years I've replaced mine twice.
> 
> 
> On 1/6/2013 3:10 PM, Darrell & Nora Kufalk wrote:
>> I was testing my landing gear on jack stands and gear pump began 
>> cycling every few seconds.  It would only do it in the down position.
>> I traced it down to the pump itself.  With both outlet tubes caped off 
>> it still cycles once or twice per second.  I pulled the pump out and
> removed the reservoir.
>> I took apart what looks like 2 check valves and they look ok to me.  
>> I'm not sure what to do next.
>> 
>> Anyone else have a problem like this?
>> 
>> Darrell Kufalk
>> 
>> 
>> 
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