Ralf,

The Outback gear doors on the 320/360 suffered a similar fate.   The original actuation scheme couldn't handle the air loads.  A small pressure differential over a large area generates a lot of force.

Chris

 

Chris Zavatson

N91CZ

360std

www.N91CZ.net

From: "bronnenmeier@GROBSYSTEMS.COM" <bronnenmeier@GROBSYSTEMS.COM>
To: lml@lancaironline.net
Sent: Monday, June 17, 2013 11:08 AM
Subject: [LML] Nose gear check 4P update

Dear subscribers,

I did the nose gear check as described Jack Morgan and Charlie Kohler
earlier. Everything went very smooth and the plane did not move at all
even when the weight on the tail and chucks were removed.

I cycled the gear 5 times and every time the nose gear door shut
perfect. This leads to the conclusion that my door shuts perfect after
take-off and reopens due to air-pressure like Brent Regan describes
below.

On the in-flight picture you can see how the door gets pushed open. This
was at a pretty low speed - approx.  140...150 kts indicated - I assume
it will get worse if I go faster.

I attached pics of my nose gear linkage versus Brent Regan's improved
nose gear linkage - if yours looks more like mine you probably have the
same problem.

Since there was so much concern about my jacks I attached a pic of the
gear check. My jacks work reliable and the plane sits sound on them.
They just don't have enough stroke. That's why I have little platforms
that I slide in and out. The set up works reliable - it is just a little
more work....

Ralf



-----Original Message-----
From: Brent Regan [mailto:brent@regandesigns.com]
Sent: Wednesday, June 12, 2013 11:37 AM
To: Lancair Mailing List
Subject: Re: Nose gear check 4P

Ralf writes:
"A friend took a picture of the belly of my airplane in flight with the
gear up. It looked to me that the nose gear door was not completely
closed."

The original factory nose gear door linkage geometry provided too low a
mechanical advantage to keep the doors closed against the internal
cowling air pressure during flight. On the door bracket, you need to
fabricate a new part with the link ball hole rotated about the hinge
centerline towards the AC center. This will give a larger effective
moment arm when the doors are closed. A slight kink in the linkage arms
is required. See pictures attached.

BTW, Selecting Gear Up while on the wheels is an incredibly bad idea.
Buy a decent pair of jacks NOW. Also, do NOT strap the spinner to lift
the nose. Remove the top cowl and strap the propshaft.

Regards
Bren Regan
--
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