I know this is an old thread, but I think I may have witnessed a similar incident on my friends Showtime.

What I saw wasn't flutter, the wing actually flapped like a bird. Mike wasn't over flying his plane, as a matter of fact, I fly mine a lot harder than he flies his.

This is what I wrote in another forum, it tells the story well.



Well the day started like any other, load a plane in the van and go to work . I was going to meet Temptation at the field, after work, to get a few flights on our Showtimes. Mike called around 8:30 and said he wasn't going to make it, he had some work this afternoon that had to get done. I said to my self, "self", I'm going anyway.

Sooooo, about 1:00 I started looking for reasons to leave the job. Sweet!!! One of the doors is the wrong size, I better go and get the right one, I'll come back tomorrow .

I had 3 or 4 flights in when my phone started ringing, "Are you still at the field?" Mike asked. I said, "Listen to this", as I proceeded to rev the throttle on my Saito 150...

His response was such that I can't write it in this forum, but you get the picture. "I'm on the way, be an hour or so".

Mike showed up about 4:30, with his Showtime and a friend from work, so I figured, "it's show time"...

I was in the air when they got there, so I played around for awhile and landed to talk with Mike. He was finishing the assembly of his bird, so I waited for him to put his first flight in. He fired it up and rolled to the line, taking off as smooth as always in a slow methodical climb. His flight went as usual, couple of dozen fast rolls in a vertical line, then slid into a hover, finally a little harrier action nice and slow. A few passes later, he came across the field again, snapped into a hover, held it for 10 seconds or so and did a 3/4 throttle climb with rapid rolls on the way up.
At the top came a stall turn, then idled on the down line. At 50 ft. or so, he leveled off and powered up. Shortly after he leveled off, all hell broke loose. The right wing started flapping like a sparrow! Mike yelled, " Flutter!"

Flutter my *****, the whole wing flapped like a bird. He immediately backed the throttle down and the plane went into a slow spiral. I heard the engine come up slowly and saw the plane level off, by this time he was at the weeds. The plane came up and went between two trees, I thought it was a goner for sure, then he was above the tree line, I said, as calmly as I could, "Mike, you better get that thing on the ground, slowly". I didn't have to tell him that, but I did it out of habit from helping newbies all of the time.

He brought the plane around real slow, just above stall speed and made a perfect 3 point landing. After we did the normal congrats and praises, for the save, we started to look at the plane. I grabbed the wing, to check for damage, and was able to flex one wing half almost an inch, you could plainly see the balsa buckle. When Mike removed the wing from the plane, you could plainly see the ribs, near the wing socket, were broken all of the way down. When the wing flapped it actually broke the ribs past the servo mount.

We couldn't see why the ribs broke, he wasn't flying hard enough to break anything, in my opinion. The only thing I can figure is there might have been a cracked rib at the end of the socket. A small crack is all it would take to start a big problem.

I figured I might as well fly mine and see what happens. So up I went, immediately slamming this thing around the sky. I was going to find out if it is a design flaw or just one isolated case. I'm sure Mike will chime in here and contest to the fact that I put my Showtime to the test. I did everything from full throttle tumbles and flat spins to high speed vertical and horizontal walls. No problems with my bird...an isolated case.

We never did get to shoot the video of "Dueling Showtimes"...another day.

__________________
Ken Thompson

Mike has since been in contact with Horizon, I'm sure the problem will be solved. With so many Showtimes out there and so few problems, I think I will keep mine, and maybe get another.