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Kit Building: Engine (and related Power Section components)


Part way through the build of this Challenger, we decided to upgrade her to a 582engine.  C-IJBN has a 503, so this will give us one of each for demos to customers so they can decide what is right for them.

I also have a bit of a fly fishing habit, and some of my favourite lakes are quite high and quite small, so with all that extra horsepower, the 582 affords a bit more jump in tight spots: density altitude affects effective engine horsepower, and wing and propeller performance.

Fuel System

Part way through completion of my fuselage, Turbulence Aviation stopped making their 15 Gallon fiberglass fuel tanks.  Thankfully, we now have a very nice (and lower cost!) 17 US Gallon welded aluminum fuel tank, so I am installing that instead.  That extra 2 gallons is about 30 minutes more range in a Challenger! 

The installation is very straightforward and the directions are quite good but one can never have too many close ups!.  A customer and fellow builder is also installing one of these tanks and is ahead of me, so I've included a few of his photos as well a few of our own.

General Tank Overview

Here's a few pictures of my tank installation.  The base is symmetrical, so I've only showed the right side were a put a notch for a fitting (which probably isn't needed by the way - I'm just fussy!

Left Side:
Right Side:
Front Right:
Notch for Site Glass:
Left Rear Quarter:
Left Front Tank Base:
Left Rear Tank Base:  I have since lined these with 3/8" thick by 1/2" wide adhesive weather stripping.
Right Front Tank Base:
The new 17 Gallon tanks have a sump built in, but mine is one of the earlier ones and it did not have a fuel sump to collect water.  So with the help of a few AN fittings from Goulet Aircraft, I've implemented the solution pictured at right.  This setup allows for about 2" of standing pipe below the fuel feed line for water collection.  Not a lot, but it is also just about the right height that it will exit the bottom fabric and only and inch or so of rubber tubing will finish the job and still allow a quick drain as part of the preflight.

If you wish to replicate my solution, you can read the AN part numbers on my invoice.  The push valve I sourced from Leavens in Calgary quite a while ago and they will no doubt have the other bits as well.

I thought about the valve under the seat idea that the tank manufacturer suggested, but am fearful of it either vibrating or being moved (a passenger "wondering what this does") into a drainage position in mid-flight.

Here's the Sump on the tank.  It clears the elevator tube at full deflection.  Good thing the designer made sure the hole wasn't in the middle of the tank!
The following pictures were provided to us by Dave in Calgary who is a CFI doing a gorgeous build and plans to provide Challenger flight training in the not-to distant future. Dave fabbed up this very nice shroud for the tank filler pictured at right.  Nice job.

The 17 gallon tanks are quite tall, so one needs to be sure to adjust the height of the provided rubber fill tube to allow you to pour fuel in from under the wing.  There is not a lot of overhead clearance in this area.  I would actually suggest getting somebody to hold a piece of cardboard at wing height and adjust the installation height make sure you can get your favourite gas can to pour and drain into the filler opening.

Dave has implemented his fuel fill on the right hand side of the airplane.  With these new tanks you can do it on whichever side you like.  Most of the Challengers we've seen have the external fuel fill on the left hand side - likely because that is where the old fiberglass tanks had their filler spout.

I'm doing mine on the right side as well as that is normally where I enter or exit the airplane, and that that is where the site tube is on these tanks .


Water Heater and Ducting

I don't want bits falling under the engine when I'm working on it, so I am enclosing the area under the heater with a thin sheet of aluminum.  Here is the cardboard test template (aluminum is expensive!)

Here are a couple of shots of the  the 582 Water Heater test fit into place on the template.  I'll replace these photos with ones showing my own fuel tank when I get time.  This is the old 15 Gallon Turbulence Tank.



We're using the most popular aftermarket throttles available for the Challenger.  They are made in St. Albert by Aero Controls and many Challengers have them.  We haven't sold a kit yet without them, and they are a bargain at under $300 including the mounting plates and all cables.

Front throttle - Inside View
Front Throttle - Outside View
Rear Throttle - Inside View
Rear throttle - Outside View


If you're building a 503 Challenger, you can ignore this part - your supplied wooden GSC prop is just the right thickness for the supplied bolts.  

If you're using a two blade adjustable warp Drive Propeller on a 503, or building a 582 Challenger, when you get to installing your propeller, you will discover that the supplied bolts are too long for the Warp Drive Hub.  Folks who have bought 582 kits from ChallengerWest - we'll be shipping you sufficient extra washers for your kits.

Forget about trying to find perfect length bolts at your favourite aircraft supply store: While AN5H-27A is about the length required for the Warp Drive hubs, and has a drilled head for safety wire, that bolt has a 24 pitch thread - which won't work in the Quad City Hub, which takes an 18 pitch thread. Use the supplied bolts and the following official remedy, provided for registered owners, on the builder support page at National Ultralight's web site at:

Do not under any circumstances even think of grinding or cutting your AN prop bolts to length - these are hardened and tempered bolts, and as grinding and cutting typically creates a lot of heat unless done properly, you could badly alter the properties of these bolts.  You do not want a de-tempered bolt sheering off in your prop hub when you torque it - or worse, in flight!

Method One - Washer Method

Here's what comes with your kit:  Prop, machined aluminum plate (red), and one washer per bolt.  Only three of the 6 bolts are shown in these photos.

The first method uses the prop plate which is nominally 0.190" thick, and at least 4 AN washers.  I


Once you bottom the bolts, you'll find that three washers are not quite enough to give enough clearance for that bolt to be torqued.

But 4 washers per bolt looks about right. 

I still want to do some careful measuring and figuring once I know how far the bolt will advance when I torque it up to make sure I'm not bottoming out.  5 washers may yet be required!

In any event, since you only get one, you'll need more!  Folks who have bought 582 kits from ChallengerWest - we'll be shipping you extra washers for your kits.

Method Two - Extra Plate Method

f you want to pretty it up, you can get a prop spinner from Aircraft Spruce and use the supplied red prop plate under the prop hub, and the spinner plate above the prop hub,  and get by with zero or one washer. 

With this approach, you can put the red plate on first ...

Then the propeller hub ...

And then the prop spinner plate, with one washer.

If you don't want to buy a spinner which comes with a plate, you can order a second red plate and use it in this position.  The red plates are a bit thinner and you will probably need a couple of washers.

And then the spinner.

Some folks like to confirm that their prop is all safety wired as part of their pre-flight, and washers are a lot cheaper than a spinner!


If anyone needs or wants a spinner, we have them in stock.

Caution:  IN ALL CASES

The number of washers required may vary across kits due to potential changes in the thickness of prop hubs, re-drive hubs, plates, etc.  So, whichever approach you choose, make sure you do a trial assembly to make absolutely sure the bolts aren't bottoming.  If they bottom then the prop won't be tight!

Warp Drive's instructions require you to retorque all bolts after 1 hour of operation and then periodically as part of regular maintenance. Make sure you do this!

Radiator and Louvres

I'm almost done!  Pictures soon!


Engine Proper

I can hear it yelling to get out of the box and  onto the airplane!  Pictures soon!


Starter and Housing

The starter housing needs to be cutaway to fit on a 582.  What a job! I did mine on the mill because I have one, and because I was way too lazy to use a hacksaw.

Forget using lexan for the cover rather than bending some aluminum.  If the lexan cracks or breaks, the bolts will work loose, which may cause the housing to move, thereby potentially engaging the starter drive on the ring gear and badly impacting things inside the engine!  Far better to bend up the aluminum plate to make a cover.

Starter Housing After Milling - Dimensions Per Instructions


The Fine Print - Caution

Ideas, illustrations and photos are the author's own work and are for information only.  
Builders of Challengers should always follow the Quad City manual.

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