Hello,

I have been having an issue with the Janitrol in our Twin the past few flights, and I'd like to get some opinions on what I should look at first. Usually, we start up and get things turned on (radios, strobes, etc.), then turn heater to HEAT, then open the fuel valve and set temperature knobs as needed. The past few flights, we could not get the heater to light during taxi or run-up. It was pretty disconcerting considering the temps have been near single digits and it would not be an enjoyable flight without a heater, possibly unsafe with no defrosters. However, it has been lighting and working as usual from about liftoff on. We always turn off fuel on downwind and shut heater off after touchdown, so I'm not sure if it would continue to burn after touchdown, but I'm thinking not. We had a pretty stiff wind one day (15G20) and I tried pointing into the wind for the run-up to see if it would light with that bit of extra airflow, but no luck.

My question is what might be causing this? I am guessing either a combustion blower is not running or not running properly, or an airflow sensor is dirty/inop. Am I correct that there are two blowers/fans in the heater? I'm not overly familiar with the inner workings of these heaters, so I'm seeking some advice here. It looks like Hartzell Engine Technologies is the service center for these nowadays, so I may try giving them a call for some guidance and parts. Has anyone any experience with them? Are they very helpful?

Thanks in advance, and wishing you all a Merry Christmas!

Zac Weidner

Zac,

Very likely that is the combustion air blower motor. Do you hear the main fan when you turn it on and do you feel an airflow? If so, it is almost certainly the combustion air blower giving you problems. If not, it might be the main fan that is buried in the heater. First thing to do is check the brushes. At least one of those can be accessed without removing the blower and motor. If the brushes look worn, replace and see if that solves your problem. The service manual covers the heater extensively so I would suggest you look there.

Is it possible that since you rurn off the fuel off the fuel while the heater is runnining that the heater has lost it fuel to start untill it get enough pressure (primed) at about the time you lift off? when you try to start it on the ground do you use the right boost pump? I was told to paint the fuel shut off knob red and only turn it off if there is a fire........

larry

It looks like the combustion blower was not running. I read through the service manual section on this, and I understand its operation a little better now. Checked the combustion air flow switch and it seems to be working OK, but the motor was not running. I took the 90° air duct off to look at the fan and gave it a spin with my finger, and it's running every time I turn it on now. It feels pretty free, and the brushes look clean and in good condition, but it's possible the bearing is getting tight. The extra airflow from nose inlet air after takeoff must have made this motor start spinning every time and it functioned normally from there.

Would it be possible and cost effective to send this motor and fan off for repair, or just buy a new motor?

Thank you for the guidance on this issue!

I think that the motor is quite pricey - $800ish if I recall. You can probably find a local shop to look at it. I live near Rockford and use Aircraft Systems (815-399-0225). They do mags, and all sorts of motors. Have always treated me well.

larry.