Defrost air flow

[Bobcllns P337]

Hi everyone
For some reason I cannot get any airflow coming out of my defrost on my Pressurized T337G. We have chased all the scats and replaced the collapsed/damaged ones, verified all the valves and control cables which appear to work normally. Is this a problem on the pressurized 337 and does anyone know of a fix for it?

[kilr4d]

Bob, have you got a leaf blower to connect to the scat tubes and confirm that the valves are opening?

[Bobcllns P337]

I do great idea will try it today thanks

[Bobcllns P337]

Originally Posted by kilr4d

Bob, have you got a leaf blower to connect to the scat tubes and confirm that the valves are opening?

Thanks for the tip John. I did get some airflow out of the defrost, enough to make a tissue move and much better airflow out of the vents below the left and right seats. I guess my recirculating fan needs to be replaced $$$$

[kilr4d]

Ask your A&P if he'll let a motor shop that works on DC motors take a look at it. It's becoming more common as the legacy fleet ages and parts cease to become available. If they can find an issue with a bearing/winding/shaft etc maybe he'll sign it off.

[Bobcllns P337]

Originally Posted by kilr4d

Ask your A&P if he'll let a motor shop that works on DC motors take a look at it. It's becoming more common as the legacy fleet ages and parts cease to become available. If they can find an issue with a bearing/winding/shaft etc maybe he'll sign it off.

John, I just had the motor fixed so I believe the squirrel cage is allowing bypass since I get good airflow from it but no pressure

[n86121]

My older T337D relies on ram air pressure, so you only get good defrost in flight.

On ground, not much at all, just from front prop backwash into ducting.

The only motor is the one mounted on the heater for combustion air flow.
You 'throttle back' that back (partially close duct) in flight because adding ram air is too much.