Finn Lassen wrote:

 Today I was finally able to do a short flight after adding/changing oil
 lines.

 It turned out to be a training flight in engine out landing.

 When I pulled back on the throttles about half way downwind, the engine
 died. Since I was at pattern altitude, good airspeed and in a close
 pattern, I concentrated on flying instead of on restarting the engine.
 The landing was uneventful. The engine started easily on the ground.

 Now, any idea on why the engine would die when pulling back on
 throttles? Someone suggested carb ice, but why now, after more than 160
 hours in similar weather?

 Finn

You will never know about carb ice until you put a carb temperature
gauge in there. On the other hand I really doubt you had carb ice in Tampa
Florida in September at 800 feet.

  From Ken Welter
  I think it was from a pressure differential between the float bowl
vent and the venturi. This  can happen if you are trying to ram air
into the carb and pressure on the vent and the velocity stacks. This
is the way I control my mixture. I use a controllable ram
pointed at the velocity stacks and at half throttle if I push in full
ram it will kill the engine. When I get to the airport I will take a
photo and send it out.

Ken, this sounds interesting. What are "velocity stacks"? Sure would like to see
that picture.

I did take the carbs apart, but aside from a bit of gel in the bowls, I didn't
find anything unusual. I guess a thorough inspection of the ignition wiring is in
order. With two sets of coils it really can only be either faulty crank position
pickup wiring or wiring supplying power to coils and controller.

Finn

 
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