Flutter

[GAHorn]

Interesting article about what can happen with out-of-balance contols. 17 ounces is a lot of weight. How can that happen?

If you have a 170A/B, raise the trailing edge of your ailerons, and while holding the aileron UP,...inspect the counterweights which are riveted to the lower skin's leading edge. Count them. Memorize it. Write it down. If ever you see a blank space between weights, and/or missing weights,... don't fly!
Same thing on the elevators on a B-model. Look at the leading edge/tips of the counterbalance area. See that pair of screws or rivets that hold that lead weight in the tip area? Are they tight? Are the lead weights held securely? (Also, is there adequate clearance between those screw-heads and the horizontal stab's outer rib? Don't want to ever get a jammed elevator, do you? Original mfr had rivets holding those wts, but a large number of aircraft have screws in that position. Make certain they are not loose or haven't backed out.)

http://www.aopa.org/pilot/never_again/2006/na0603.html

[3958v]

I never hear it mentioned but my ragwing has a weight in the front of the rudder. The elevator is not balanced. We just had a Mustang II Experimental which experienced rudder flutter at the next airport over. Pilot landed with just one bolt holding the vertical stabilizer on and rudder cables completly disconected. To make matters worse he had just climbed through an overcast layer when it happened. The plane was so badly damaged that the insurance company totaled it. So flutter should not be taken lightly. Bill K

[cessna170bdriver]

If you have a 170A/B, raise the trailing edge of your ailerons, and while holding the aileron UP,...inspect the counterweights which are riveted to the lower skin's leading edge. Count them. Memorize it. Write it down. If ever you see a blank space between weights, and/or missing weights,... don't fly!

Also check the shop heads of the rivets holding those lead weights. Several years ago during an annual, my AI found several shop heads missing, and was able to pop several more loose with his fingernail. I don't know if it's a dissimilar-metals problem between the lead and aluminum, but this is the only area on my airplane I'm aware of corroded rivets.

Miles

[n2582d]

I've added Service Letter S.E. 71-27 to the Maintenance Library. It deals with corroded rivets which attach the counterweights.