Elevator flutter when pulling 2.3 G's

W

wldempsey

New member
1976 Decathalon 8KCAB
A flutter developed when pulling 2.3 or greater g”s. It emanated from the trim tab forward to the stabilizers. A great deal of work has been done to solve this problem and it has been reduced but not eliminated.
The following has been done:
Checked elevator cable tension and elevator trim tension
Checked elevator trim pulleys
Replaced elevator trim tab
Checked elevator trim balance
Checked stabilizer incidence
Checked stab brace wire tension
Recovered elevators and stabilizers
Checked free play in hinges
Examined fuselage longerons and stab mount cluster looking for cracks
Checked motor mounts

At this point the flutter continues to manifest itself, but only in the elevators, under both power on and power off maneuvers of 2.3 g’s. Any suggestions?
 
I am curious why you say or how you determined that the flutter originates at the trim tab and not somewhere else in the horizontal stabilizer?

You indicated it doesn't matter power on or off. What about speed? Is the flutter worse at higher speeds and same G?

Does it flutter when you are loaded in negative G? Roll inverted and push up.

You can post your question on the "Acro exploder". Lots of aerobatic experience and people who have broken airplanes while doing so there.

Link to Acro exploder:
http://acro.aerobaticsweb.org/iac_exploder.html

Bill
 
Bill,
Thanks for your suggestion re: inverted flight; it will be tried.

Thank you for recommending the Acro website. I sent them my memo and received five responses in one day.
Several suggested thing that have been done but some new ideas came forth which we will explore.
Great piece of advice. Thanks again.
 
It would be good to see some photos. Flutter or buffet? Wake from something loose at the wing root or door?
 
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