These are pics of all the exciting pieces that go into a Janitrol Model S50/D83A28 heater that was factory equipment for the early Baron and Travel Air (probably up to 1973 vintage, but check your parts catalog to be sure). Section 10 of the Beechcraft Maintenance Manual also has some good guidance for Janitrol heater maintenance as well and you should follow those guidelines.

The Janitrol Parts Catalog & Illustration for the D83A28 is HERE

The Janitrol S-Series Heater Maintenance Manual is HERE

Kelly Aerospace Heater Parts Catalog & Price List is HERE

Replacement Heater Parts Sourcing for these Janitrol units can be found at C&D in Buchanan, MI 269-695-7469. The good news is that they make these parts available, the bad news is that they are horrendously expensive! When was the last time you bought a spark plug for $100? (You fine wire guys sit down and shut up........LOL).

Here is another resource for Janitrol Service and Parts: Harold Haskins

And yet another source for Janitrol Parts is Cumberland Aero. Baron owner Pete R. reports Cumberland had the best price for the spark plug. Geez, anything has to be better than $100 some other folks are charging!

Cumberland Aero

Despite the horrific expense of these parts, this model of Janitrol seems like a pretty robust design and with regular bi-annual maintenance of the spark plug, electrode and your original nozzle, things should be toasty warm, but that's just my humble opinion.

SPECIAL NOTES FOUND IN MY S50:

1. I learned that in addition to a good clean nozzle, spark plug and electrode, a very important piece of the heater equation is the spark plug wire .

I found severe arcing through cracked wire insulation in the ends that was contributing to poor/intermittent heater performance. Gee, it was only a 40 year old wire! So, make a note to self, change out that spark plug wire if it is decades old.

My IA had some solid core wire and ceramic insulating ends, however, C&D has a repair kit consisting of fresh wire and connector ends that will enable you to make up a new wire to fit inside your existing braided connector. Use some safety wire and a liberal dose of DC-4

to pull your new spark plug wire through the semi-rigid braided connector.

2. I also tested the overheat circuit of my S50 heater to be sure that the unit shut down as designed at the 300F plenum temperature. The overheat thermostatic switch resides in the furthest aft position of the heater, just aft of the heater combustion chamber.  (PS: This picture was taken in 2004 to point out to the selling broker that the overheat switch was not connected to ground)

What I did to check mine was run my heater at highest heat setting in my hangar with about +1C ambient air temperature. I used an infrared pyrometer to measure the plenum temperatures at the rear of the heater and in the plenum duct on the co-pilot side where the thermostatic switch is located.

I found that under these conditions my overheat switch functioned and did it's job of blowing the 5 amp fuse in the circuit. My IR pyrometer recorded a plenum duct temp of about 235F downstream of the location of the overheat switch. The overheat switch is fed from the same power source as feeds the ignition coil, fuel pumps and fuel solenoid valve, so when the other side of the overheat switch goes to ground, my heater no longer has fuel or ignition.

We made an adjustment in the thermostatic switch cable:

so that the highest heat setting makes for a lower plenum temperature (about 210F) and does not blow the fuse.

My subsequent trip north at 11,000' with an OAT of -8C allowed for low heat settings to make the cabin quite comfortable. I'm expecting that when we get colder OAT temps, I'll have enough heat setting to be able to be comfortable.

If you live or travel to frozen tundra territory in your Baron or Travel Air, things get mighty uncomfortable in a hurry in  the winter temps that can be experienced up there at altitude, so make this a definite checklist item for your annuals or check it every two years.

NOTE: All of the below operations were done under appropriate A&P supervision, so get yourself some supervision or help your A&P/IA with a link to this page so that they can be briefed on what to expect in there if they have never done these heater maintenance operations.

25 November 2009 NEWS FLASH: GOOD NEWS, Mark M. @ Dodson came to my rescue with a complete low-time (yeah they included the Hobbs showing 43 hours) S50 Heater for about the same cost as some of these guys get for a new Ignition coil/vibrator combo! If you have heater woes give Dodson in Kansas a call (785) 878-4000 and tell them CSOBeech sent you.

This is the heater head where all the business parts are fitted. At 12 o'clock is the $100 Spark Plug

. At the 6 o'clock position is the electrode, the spark plug and electrode meet in the center

 with a gap for spark arcing. At the center position is the fuel spray nozzle which gives a fine

 spray of fuel to be lit off by the spark.

This is the heater data plate, on the right side (co-pilot side) of the unit. 

This is the heater blower. The first picture is the front end and the one on the right is the rear of

 the blower assembly. This blower assembly hangs in the front by some screws and the rear by a

 clamping strap to the front end of the heater. I made sure the front end was clear of obstructions

to flow air. On the ground the blower runs (and only ONE of the fuel pumps fuels the heater), 

when the gear is in the wells the blower does NOT run (BOTH fuel pumps are actuated with gear 

in the wells), you are running off ram air coming into the nose cone. There is a shutter mechanism 

on the blower, this is called the "Iris Valve", you have a cabin air handle on the pilot side at the 

lower part of the instrument panel, when you pull this handle you pull the shutters closed on the 

Iris Valve and LESS air comes in the cabin firewall vents. When you pull this all the way closed a 

microswitch closes and shuts the heater down because you are not flowing any air and that 

would be very bad to have all that heat happening and no air coming across the heater can 

(DUH!) Cleaning the iris vanes is a good idea to insure smooth operation. Many people suggest

pulling the Iris halfway to get a warmer air temp into the cabin. I've not tried this technique as I'm 

a big fan (pun intended) of flowing as much air over that hot can as possible. You're the PIC, you 

decide!

Blower motor data plate information.

Dirty electrode removal.

Bead blasted electrode cleaned up.

C&D replacement nozzle

This is the area under the heater showing the blower motor strap clamp to the front of the heater 

assembly. The picture on the right shows the Iris Valve actuating mechanism and the 

microswitch and coil/ignition vibrator location (coil/vibrator removed). I lube this area of the

 mechanism regularly with CorrosionX).

This is the area that must be disassembled to remove the nozzle plumbing. This is directly behind

 the coil and ignition vibrator (torpedo looking thing) under the nose shelf. The coil/ignition unit is

 held on by two band clamps with phillips screws. See the screw holes in the picture. The

 stainless enclosure has a little cover on it with two long screws to the front and two short ones 

to the rear. The two long ones reach all the way down to the nozzle plumbing fixture. The two 

short ones hold the cover to the stainless enclosure. There are two screws in the base of the 

enclosure that are securing the nozzle plumbing to the outside of the heater can structure. I 

left those in place for rigidity. I then removed the fuel line fitting going to the 90 degree elbow.

While holding the rear of the nozzle plumbing, I fit a small wrench in there to loosen the 90 degree 

fuel fitting. After I removed the 90 degree fitting, I removed the last two screws to the rear of the

nozzle plumbing fixture and the whole piece of plumbing to the nozzle was then loose.

I removed the nozzle with a 5/8" socket.

Here are the dirty and nasty things that were found in my neglected heater nozzle (your humble

 CSOB is guilty of 5 years of neglect and the CSOB before me is guilty of a number of years as 

well). This definitely impeded proper fuel flow and spray pattern atomization for my heater 

performance.

Of course, you can clean the old nozzle and make it serviceable again (the Beechcraft

Maintenance manual approves this), however, I used my Emergency Revocation powers to

revoke my CSOB card when I was buying the spark plug and purchased a new nozzle as well.

Pictured above is the Thermostatic Limit Switch. It is located just above the co-pilot's rudder

pedals and just under the firewall air vent where you can hardly reach it (big surprise ).

The cable determines the set point at  which the heater will cycle on and off. The little cam with the

white plastic molded lip is connected to a coil that sits in the heater plenum and turns as the

plenum heats up and cool down, thereby actuating the micro switch. The micro switch in turn

passes power to the fuel solenoid valve (this shut off valve is just downstream of the fuel pumps in

the nose gear well) which opens to allow fuel flow to the heater in the presense of 24 volts. This

micro switch PN is no longer produced, so if you have a failure here you may have to search out

some alternatives. Here is what Beech lister and B55 Baron owner Richard S. found that might be

able to be modified to work

The above is: WZ-2RW822-A2. Available from Mouser HERE The pdf Data Sheet is HERE

Always be sure any part substitution is approved by your A&P/IA for return to service. A review of

the AC 23-27 Parts and Materials Substitution Guidelines could be worthwhile.
 

Your ignition coil/vibrator is TU?

Here is a pirep from Baron owner Joe B.:

The culprit was the ignition coil, PN 11C30-1. It was not very expensive by aviation standards. I

shipped the old coil and wire to Aircraft Heating and Electrical, 1635 Beltline Road

in Redding, CA 96003 916-246-HEAT (4328).

They tested my old coil on the bench and it would work, then shut down when it got hot. After it

cooled off, it would begin working again. The coil is supposed to fire all the time, even when the

thermostat has cut off heater. They shipped me a new coil and wire. Problem was solved.