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From: "Christopher Zavatson" <Christopher.Zavatson@udlp.com>
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Subject: Re: [LML] LNC2 Nose Gear Door
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<<One thing that can contribute to this problem is if you drop your gear
at
too high an airspeed.  I usually slow to 120 MPH or less before
dropping the
gear.>>
I'll bet most rub at 0 mph while up on jacks.

When the gear pump is reversed and the gear drops, initially due to
gravity, each of the main cylinders work as high speed pumps causing a
pressure surge in the up side circuit.  This initially fights the down
springs on the small gear door cylinders which are also trying to pump
fluid to the high side circuit.  You can see a related effect if you
stop the gear half retracted and then manually lift and lower one wheel.
 The others will move in the opposite direction.  The gear door circuit
is not quite as simple because the sequence valve is inline acting as a
one-way check valve.  The falling gear may momentarily keep the door
from opening,  but will not cause it to close back up because the
plunger is no longer depressed.  Once the pump catches up, everything is
powered down by fluid pressure.  A much stiffer spring on the nose gear
door cylinder could alleviate this issue, but may not be practical in
terms of sizing.  It has to be strong enough to overcome the pressure
spike generated by the falling gear, yet not so strong that the cylinder
can't close the door.  On the outback main gear doors, the small
cylinders are already stretched due to the larger gear doors with a
pronounced camber.   
<<I think most of us LNC2 owners are resigned to the fact that the nose
gear
pushing the door open to get out is an inherent characteristic of the
design.>>
Yep.  If scratches really bug you, a nylon or Delrin slider of stricker
is probably the easiest way to keep the door scratch free.
Chris Zavatson
N91CZ