REFLECTOR: NOSE WHEEL GOT SIDEWAYS

[Dave Black]

Oscar,

> I am a new Velocity owner, and after replacing the hy hoses I
> did the gear test and hear a slamming noise, apparently in
> the front doors. Is, I believe the problem that you are
> discusing. Can you please, tell me in which area you recomend
> the valve be installed? I have a top loader, rg. Perhaps the
> early hases replacement was due to this problem?.

I have a top-loader as well. 

>From listening to dozens of owners describing the nose door slamming problem,
I've come to the conclusion the nose doors (and specifically the sequence
valve) have never worked as Velocity intended. One would expect the nose doors
to close as soon as the nose gear retracts and the button on the sequence
valve is pushed. But they NEVER do. The doors jiggle a little bit when the
nose gear first retracts, but don't close until the main gear is fully up. I'm
guessing that the designer of the retraction system observed that the nose
doors did not operate as expected, but decided it worked well enough that they
never diagnosed the problem.

My investigation showed that under hydraulic pressure the sequence valve
requires a great deal of force to activate. It's not easy to push that button
when the sequence valve is pressurized. So if the button is mounted where it's
easy to get to (as in plans) the nose gear mechanism simply does not have
enough force or torque to push the button. The inertia of the gear coming up
activates the button momentarily, which causes the nose doors to jiggle but
not close. Only after the mains are fully up does the hydraulic pressure go
high enough to provide the torque needed to activate the sequence valve and
close the doors. Trouble is, by then the hydraulic pressure is so high the
doors slam with authority.

Try this: With the plane on jacks, retract the gear. Note that the nose gear
comes up first, followed by that little jiggle of the nose door. Next the
mains come up. Finally the nose doors slam. This is the way the nose doors
work in all the RG Velocities. It's not the way they were intended to work,
but they do work. 

Now, try this test: Open the nose hatch and repeat the retraction. But this
time, when the nose gear reaches its upper limit, grab it manually and pull it
up the last half inch or so. You will notice that the nose doors close
immediately, without slamming, and before the mains retract. That's because
you have provided that extra force needed to actuate the sequence valve when
it is supposed to be activated. 

Most owners don't mind that their nose doors close late and slam. Most of
those who do mind install flow restrictors in the hydraulic line to the nose
gear actuator. Adjusted properly, the restrictor stops the slamming, but still
does nothing to get the door to close in the correct sequence. 

Initially I moved my sequence valve to a point only 2 inches in front of the
rearmost nose gear pivot in the keel. It worked perfectly. The doors closed
gently as soon as the nose gear was up. But that location presented
maintenance issues -- I could hardly get to it. 

So I came up with a better way. I mounted the sequence valve in the
comparatively accessible forward part of the keel, just to the left of the
factory's location. BUT, instead of having the nose gear mechanism push the
sequence valve directly, I installed a lever to multiply the force applied to
the button. The sequence valve is mounted to the side of the keel. A gate
hinge (with long arm) is mounted right above the sequence valve. The button is
pushed by the hinge when the far end of the hinge arm is pushed down by the
nose gear mechanism. The long arm of the hinge provides about a 10:1 leverage
advantage. Thus the button gets pushed at the proper time, and the nose doors
close very smoothly. 

I will get you a picture of this little mod the next time I'm at the hangar.
The mod takes a bit more effort than installing a flow restrictor, but it
actually fixes the problem rather than just putting a Band-Aid on it. 

Dave Black
ShortWing RG