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"The Kolb Quit" bit me in the butt yesterday

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Victor Bravo

Well-Known Member
Supporting Member
Joined
Jul 30, 2014
Messages
13,443
Location
KWHP, Los Angeles CA, USA
Saturday was a bad day for me. I was in control of a friend's airplane, and it got damaged. Truth be told, in the few minutes before it got damaged, we almost got seriously injured or worse. This story is being presented as a cautionary tale. The older / more experienced pilots here will immediately identify a point where I should have pulled the plug and stopped the accident before it happened. Nobody got hurt, airplane is repairable, but my ego is on life support over at the ER.

"The Kolb Quit" is a slang name that was given to a specific characteristic known on this type airplane. When you get down to 4 or 5 feet AGL, reduce throttle, and get ready to flare and "feel" for the ground, the airplane quits flying and drops in catastrophically.

Here is a short description that I posted on another internet mail list:

----------------
Well Kolbers I am completely humbled and embarrassed.

Because I got distracted by two or three (legitimately serious) things unrelated to the actual landing, I fell victim to the Kolb Quit and **** near wrecked Jimmy's new Mark 3 today.

I flew out to Camarillo in the 172 this morning early, and after some radio equipment issues we were ready to go. Jimmy took off and we headed out away from the ultralight strip. Immediately it was obvious to both of us that there was a somewhat serious control problem. The control force on the ailerons was very heavy, and it took two hands to roll the aircraft to the right. One hand, but heavy, to make a left roll/turn.

I was given control of the aircraft, and experienced this first hand. The roll rate to the right was atrocious and took both hands to accomplish. Pitch control was heavier than I expected but easily controllable.Yaw control was well within the "Reasonable" range.

Jimmy and I made two or three low passes over the ultralight strip, and I was given the task of landing the airplane. The landing pattern at Camarillo UL strip was very tricky and unsafe as far as I am concerned. In order to not fly over a corporate aircraft facility and their outdoor fuel tanks, the base leg of the pattern is flown extremely close in. Base leg is essentially over the approach end of the strip. Left traffic only, at or below 300 AGL.

The first landing was safe, but bouncy. The Kolb Quit dropped us in from about 2 or 3 feet, to my complete surprise. We taxied back to his hangar andtried to fix the aileron problem.

The second takeoff was made, and there was only a small improvement in controlling the aircraft. It still required two hands to roll the aircraft to the right, and this was needed turning a very close-in base leg, with a hard left turn from base to final. Rolling out of this turn required a two handed right aileron input with a very very slow and not positive result. At 50 feet AGL between a large hangar and a tree.

We made a couple of low passes,and Jimmy reminded me I was far too high and fast, so we went around. On the last pass, he thought I was way too slow. I used the speeds and and techniques I would use in a Taylorcraft, but I did not remember the Kolb Quit. Pulling the throttle back to idle on short final, the airplane landed very hard and seriously damaged the right main gear leg. The airplane got out of hand and headed across the runway for a chain link fence. I applied full power to get it away from the ground, but the high thrust line resulted in us screaming across the runway at below fence height. Full back stick was not getting us any higher than below fence height. We finally climbed over the fence with very little room to spare.

Next time around one of the guys was standing in the middle of the runway waving his arms. What could this be? I finally looked out over to the right side of the aircraft, and saw the right main wheel up at eye level. I knew instantly that this was going to result in a "crash landing".

The next time around, I managed to keep it going faster, and put it on the remaining wheel with no Kolb Quit, but it of course settled down on the one wheel..... and the other wingtip, and proceeded to groundloop and bend one of the wing tips.

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Looking back in hindsight I should have pulled the plug on the entire episode after the first landing, and not flown the second (test flight) at that location. Moving the location to another airport would have allowed me to make better choices in terms of setting up a straight and more manageable landing approach, which would likely have allowed me to land without damaging the aircraft.

The cause of the aeileron control problem has still not been identified.
 
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