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----- Original Message -----
Sent: Monday, September 27, 2004 10:16 AM
Subject: Your door problem
There is no spring to help the door close.
The spring fitted is to open the door when you go to emergency extension of the
gear. When you do this, all the pressure is released and the nose gear
door and the two inner doors on the main gear are pushed open by
springs.
My right hand side inner door has a habit of
closing much later than the other doors and I have partially explained it, at
least to myself by blaming the prop wash. However it does close eventually
and is fine on the ground. Have you flown a full circuit and then asked
the tower to check again?
If I have the plane on the jacks and I retract the
gear the mains go up first, then the nose gear retracts and FINALLY the inner
doors and the nose door close as the pressure builds up to the pressure switch
cut off point. I have gauges on my system and the pressure can be seen
clearly as it rises and the inner doors finally close. This tells me that
loading the springs requires a deal of effort and the extra air loads may be the
problem if other factors are in play.
However the majority of 360's work OK so the
question is how does your plane differ? It is obvious that the air loads
are a factor if the door is fine on the ground. However the force
available to close the door must be very marginal if the air loads are
sufficient to keep the door open. Is it the cylinder itself? Is the
actuating rod bent? Is the cylinder properly aligned to give an in line
pull to the door. Is the bracket on the door the correct size in terms of
the height of the cylinder attachment point above the door? (This distance
determines the leverage you get) Are you quite sure that you did not use
teflon tape to seal the threads on the cylinder and that some if it is not
blocking the ingress/egress to/from the cylinder. Do you have
two hoses to the cylinder? i.e. not only a closing but also an
opening hose? If so you will need to check that as the door closes the
fluid on the other side of the piston can flow freely back to the
reservoir. Does the door move easily on its hinge? Once you are 100% sure
that all of the above is OK, you could take off the emergency spring that
opens the door and fly the aircraft and see if the door closes then. This
involves some element of risk beacause if you have a real emergency the nose
gear door will only open under the weight of the gear pushing it down plus the
thrust of the emergency extension cylinder. This is your
call!
If it does not work with the spring off then you
are on to the verificaion of the ability of the sequence valve to provide
unimpeded flow. This goes to the physical condition of the valve as well
as the adjustment. If all is well there then you need to do the check I
mentioned to see that there is no blockage in the line, which is unlikely
but........
If you end up wih no results from the foregoing it
would be a good idea to get two pressure gauges and "T" them into the lines at
the pump. They will tell you what is happening to the pressures in the
system, bearing in mind that the pressure at any point in a system like ours is
the same as at any other point. The gauges are not expensive, $20 to $25
each.
I cannot think what else you could do other than go
into the mail list archives which is a treasure trove of other people's
experiences and in some cases, solutions.
Where do you live in Oz? Haven't been there
in years but used to go into Sydney from Los Angeles and then out west to the
Pilbarra. What a place. The only place I know where the cold water
in your hotel room would scald you after its trip across the
desert!
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