Two weekends ago, I declared an emergency in my Cozy. This was not the first time for me to declare an emergency. This is the third time in GA aircraft (once in a C-172 with 2 extremely fouled cylinders----and once in my Longez when I blew a hole in one of the cylinders), and I have declared 3 times in military aircraft.
Took off from my home field under VMC on an IFR flightplan. Leveled off at 5000ft. Approach then cleared me to climb to 7000 ft--I retrimmed for 140 mph for the climb. After about 500 ft of climb, the engine was getting a little rough----it did not feel right. RPM and MP looked good. Electronic ignition to off---no change--then back on. Mag off---no change either---back on. Mixture already rich for the climb. But holy smokes----the oil temp was smoking hot----and the CHT alarms were going off also! I throttled back with no change in any temps or vibration.
I punched up the nearest feature on the GPS and told approach that I was going to have to set down at the nearest field. They asked if I was going to declare an emergency---and I said "Yes". They gave me a steer to the nearest airport----which was the same one I had punched up on the GPS---and it was only 12 miles away. With a dead engine, I knew I could make 18 miles easy with no wind---my engine was still producing thrust but did not know for how long.
I looked around the cockpit again to see if anything else would jump out at me. I looked at the speedbrake switch (tiny switch by the pitch trim lever)-----It was DOWN!! I checked it right before takeoff!! I must have bumped it when I retrimmed for the climb!! OK---speedbrake up. Instantly, the "rough engine" got smooth and the temps started to fall. I told approach that I thought that I found the source of my problems---but would be making a precautionary emergency landing regardless.
Couple of lessons learned.
-Need to protect the three position speedbrake switch or move it
-Any "engine roughness" or temp problems----check the speedbrake position
Other observations
-On my longez, this would have never happened since I had the plans built speedbrake which autoretracts when you get a little faster than the approach speed
-Read another account of a longez with an electric speedbrake where he let it down to penetrate through a cloud deck. Once he got through it, the electric speedbrake failed and he could not retract it. He was at a lower altitude and had futher to go---smoked his engine. My take away---don't purposely use the electric speedbrake unless you are ready to land
-In the landing pattern, you can hear the speedbrake go up and down---at full power, you can't
-In the landing pattern, both the longez and Cozy kinda "shudder" with the speedbrake down----this is expected. I did not recognize this shudder at 140 mph and at full power------I will NOW!
In the end---I was kind of embarrassed---I hope others can learn from it.
