2005 Masters maneuver #4 - Warning

[Cameron Smith]

SAME THING ON MY HYDE-A-WAY!! I installed a larger False Rib from the
bottom & used Elmers Polyurethane on Foam areas! Cause it swells & fills
any Voids in the foam areas. Don't get any in your sockets!!  
   Now back to trying to get a C O N S I S T A N T  Snap!
 
-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]
On Behalf Of Grow Pattern
Sent: Friday, January 07, 2005 7:40 PM
To: discussion at nsrca.org
Subject: 2005 Masters maneuver #4 - Warning
 
This is a sort of public service announcement, or at least please regard
it as a "Heads-up".
 
For all of you who are flying or will be flying the Reverse Avalanche
you might want to check your wing tubes and phenolic tube wing supports.
 
It seems that if you go into the snap a bit hard you can bend your wing
tube or, in the worst case scenario break, your wing. The plane is
pulling some G's at the bottom of the loop and then you add more by
putting in a lot of elevator to get a good break for the snap.
 
Last year I had several incidents reported to me and my initial reaction
was to say that they were probably not flying the maneuver correctly.
"You need to slow the plane down at the bottom of the loop", I said. I
must add that what I said did not impress an FAI and pilot and District
masters champion very much. :-(
 
So strapping on my asbestos underwear I decided to do some testing of my
own. At the end of November 2004 it was nice here in NJ. I took the
Focus-2 and the Temptation out for a day of Masters 2005. Both planes
were inspected for tube tightness and the wing covering touched up with
the glove-iron.
 
Twelve flights later and an average of 10 reverse avalanches in each
flight I went home thinking all was well. (It got cold and a bit dark
too).
 
Back in the shop the first thing that I noticed was new wrinkles in the
covering on the Temptation wings. Nothing was loose. To test this I put
the wing-tube in the wing and leaned on it a little. All was well but I
was beginning to think that the wing must have flexed to cause the
covering to loosen up. A bit like what the covering sometimes does
around the aileron horns. It this case it was at the roots above the
tubes - both sides.
 
Then I turned to the Focus-2 wings. Not good! The wing-tube could now be
moved up and down and I could hear foamy crunches in both of the wings.
Both wings have Carbon tube wing tubes and it dawned on me that they
could not bend (much) or stay bent. That is why I had not seen this
before. The forces were applying themselves to the ends of the wing
tubes. I opened up both panels and added epoxy and micro balloons to
stabilize the sub ribs. It was an easy repair but could have been a lot
worse if I was not looking for it.
 
I am advised that stress damage is cumulative and that it does not show
up initially. It certainly had not revealed itself while I had been
demonstrating the 2005 schedule over the late summer of 2004. So where
does this leave me?  I think we have a potential problem that requires
frequent preventative equipment inspection depending upon the planes
that you fly. If you can slow down your plane and it is at around 10 lb
you may never see this happening.
 
I would strongly advise checking your wing with the wing tube in place
to look for tube movement. Also look for straightness if you have an
ali-wing-tube.
 
This situation is a bit unique for me. It is the first time I have been
involved with a maneuver that you don't know you are doing it wrong
unless you fly it that way too many times. And then only if the wing
shows damage or even worse it breaks in the air.
 
Regards,

Eric Henderson.
 
P.S. The only time I remember seeing a reverse avalanche before is in
the hardly flown? current FAI Finals schedule.
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