REFLECTOR: RG Problem

[Tom Martino]

This can also happen when switch contacts are going bad.  The "voltage
fluctuation" created by turning the (high amp) voltage light on and off
could be enough to "tap" the switch.

When switch contacts are dirty or burned ... all sorts of weird things
happen:  delays, stuttering, less than full voltage, etc.

 

-----Original Message-----
From: Dave Black [mailto:dvblack at comcast.net] 
Sent: Tuesday, August 03, 2004 1:59 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: RG Problem

John,

> Lately, when I hit the gear up switch, nothing happens.  If I turn off
> the landing light, then the hydraulic pump comes on and the gear goes
> up.  If the landing light is not on to begin with, then I need to
> quickly switch it on and off to get the pump to come on.  Any ideas
what
> is going on?

Nothing solid -- just brainstorming...

Presumably there's no interconnection between the landing light and the
gear
pump. In which case, the only common point I can see is the main
electrical
supply. The landing light may be drawing so much current that the
voltage to
the gear pump drops below its operating level. Switching off the light
raises
the system voltage. If the light is off anyway, by this theory the pump
should
run OK. But maybe the voltage spike created by switching on and off the
light
is enough to give your pump that extra kick. 

Certainly this is not the way it should operate. I am assuming the pump
originally operated correctly and only recently began this behavior. 

The first thing I would do is put a voltmeter across the hydraulic pump
to see
when it's getting voltage and when it's not. Also check what the voltage
is. I
would expect 12v or more when the gear is operating. If it does not run
when
it's supplied 12v, this would point to a marginal gear pump motor.
Further
bench testing should confirm this. A variable DC power supply could come
in handy.

If the hydraulic pump is receiving significantly less than 12v, I'd
check
voltages elsewhere in the electrical system. If voltages are low
generally,
that could point toward a defective alternator, regulator, or battery. 

If the hydraulic pump is not receiving voltage when it should, trace
back
through the wiring to find out where the circuit is broken. I'd be
especially
suspicious of any relays in that circuit. 

I suppose it's possible you may have an intermittent limit switch in
your
hydraulic system. I don't know how a voltage spike caused by cycling the
landing light could reset a limit switch, but stranger things have
happened. 

Sorry I can't immediately identify the source of your problem, but hope
these
tests can help lead you to a diagnosis. 

Dave Black
Shortwing RG
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