REFLECTOR: NOSE WHEEL GOT SIDEWAYS

[John Dibble]

My sequence valve is mounted in the nose compartment and is activated by the gear leg
near where the bend is.  First my nose gear retracts 95%, then the doors close 95%.
After the mains retract, the nose gear fully retracts and the doors "snap" shut.  It
doesn't seem like slamming and I am happy with it.

John

Dave Black wrote:

> 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
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