Challenger XL-65 Light Sport Aircraft Build Project

In December, 2011, we received a new Challenger II XL-65 light sport aircraft kit from the Quad City Ultralight Aircraft factory.

As with the XS-50 project, we will chronicle the build on-line as it comes together from receiving the boxes off the truck right through to the test flight and delivery to the customer.

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Dec 12, 2011: Aircraft Kit received. Began unwrapping fuselage and wings and checking for damage and receiving in parts. Hung up wings. Mounted fuselage on saw horses. Cut up boxes and bundled cardboard for re-cycling.
Dec 27, 2011: Continued un-boxing parts and checking off parts from the packing slips. Put parts on shelves and organized. Cut up boxes and bundled cardboard for re-cycling.
Dec 28, 2011: Finished unpacking fuselage. Installed reinforced belly mod using 3/4 x3/4 x 1/16 aluminum angle below the horizontal cross member of the landing gear. Then added 2 gussets about 4 inches in front of the landing gear legs along the 2 sides. This will enable the plane to be lifted from below with a hydraulic ATV lift without crushing the belly.
Dec 30, 2011: Built small storage compartment and large storage compartment behind rear seat using .025 aluminum sheet. Installed FG-99 fabric gusset on tail and small 2×2 gusset for fabric support below tail. Drilled and riveted seat bottoms. Drilled and riveted firewall. Installed tail wheel assembly with Clecoes. Will paint first before riveting in place. Cut rear shoulder harness slot in rear seat back.
Jan 2, 2012: Finished sides of large storage compartment with .025 sheet aluminum. Added 2 more belly reinforcing gussets. Installed sheet metal fabric attachment strips alongside the rear cockpit.
The side fabric attachment trips will provide a good solid area to join the two fuselage fabric side pieces.
Jan 3, 2012: Built and installed an avionics shelf in front of the cockpit. Made the heater pan for the Sheer Tech heater and riveted it in place below the engine area.
The heater pan that will support the Sheer Tech heater is made from .025 aluminum sheet.
Jan 4, 2012: Built a battery mounting box and installed the battery just ahead of the heater pan. Installed a terminal strip for the battery and voltage regulator wiring. Installed the battery wires and grounded the battery negative terminal to the airframe. Drilled holes in the fuselage belly gussets for the wiring and installed rubber grommets. Ran the 12 volt power wires from the battery compartment to the avionics shelf as well as the primer tubing. Drilled holes in firewall for engine wires.
Another view of the battery mounting box just ahead of the heater pan under the engine mounting area. It is made from .025 aluminum sheet and 1/8 x 1/8 stainless rivets.
Jan 6, 2012: Ran the 10 engine wires for the temperature gauges from the battery compartment up to the avionics shelf and installed a terminal strip for the 5 engine temperature senders. Began building the door frames. Installed the ceiling frame and built the right door frame. 3 hours
The engine wires and primer tubes passing through rubber grommets in holes drilled in the fuselage belly gussets.
The rear sheet aluminum surface of the large storage compartment provides a nice mounting area for the voltage regulator (not yet received) and a couple of wiring terminal strips.
The door frames are built on the fuselage. A space is kept between the door frame and the surrounding fuselage frame to prevent interference and wear after completion. The kit includes spacers but the builder has added 4 extra washers on top of the spacers on the side rails to make the space there about 1/2 inch. The other 3 sides of the door have about a 1/4″ space to allow for movement and prevent binding and interference.
Jan 8,2012: Installed streamlined fuselage mod behind rear seat. This will make the door blend into the fuselage. We will also be building a small door here to make easy access to the battery compartment.
The streamlined fuselage modification shown from behind and above. Note the 3/4 inch x 1/16 aluminum angle used to support the curved 1/2 inch tubes just before they curve in toward the firewall. This will prevent the tubes from being pulled down by the fabric when it gets tightened. The tubes are just below the plane of the ceiling frame.
The rear of the door frame and the 1/2 inch tube that forms the fuselage frame. The fuselage frame tube is actually the last tube that would be otherwise used on the door frame but instead is fastened to the fuselage. Its curve matched the curve of the door frame perfectly. Note that STL-16 stainless steel L brackets are used to hold the fuselage frame in place with 3/16 rivets.
The top of the rear door frame showing where it joins the fuselage frame and the ceiling frame.
Jan 13,2012: Built left door and left side streamline fuselage mod. Started battery bay door frames.
Jan 14,2012: Built right side battery bay door.
Jan 15, 2012: Riveted right side battery bay door.
Jan 16, 2012: Built and riveted left battery bay door.
Jan 17,2012: Installed gascolator and fuel system inlet tee with quick couplers. Installed fuel shut off valve and ran fuel lines.
The fuel shut off valve installed in the cockpit right side in the side rail gusset alongside the pilot seat back.
Jan 18,2012: Cleaned and sanded cockpit doors. Riveted cockpit doors. Installed nose cone storage panels. Installed fire wall extension sheet and installed sound proofing foam sheet.
Storage compartments are made in the nose cone by installing a sheet metal panel on either side of the nose to close of a space between the panel and the side of the nose cone. Great for water bottles, maps, flight supplements, etc.
Sound absorbing foam sheeting 1/2″ thick with adhesive backing is placed on the inside of the firewall.
More sound absorbing foam on the back of the large fuselage storage compartment.
Jan 30,2012: Built and installed the rudder push rods. Installed the landing gear legs into the weldments, drilled and bolted. Installed the tail fin and drilled bolt holes in fin weldments. Installed the rudder. Then fabricated the fin extension over the rudder and drilled and riveted. Drilled holes for rudder hinge rivets. It is important to install the rudder first matching the bottom hinge to the eye bolt on the fin mounting weldment. Then fabricate the fin extension to match the height of the rudder.
The XL-65 tail varies from the LSS tail shown in the instructions in that the fin extension over the rudder is shorter in height. The best way to build it is to first install the rudder and then fabricate the fin extension over top of the rudder to suit.
The fin extension is kept straight and true during fabrication by clamping a pair 3/4 inch aluminum angles to the fin and the extension assembly. The gap between the fin extension and the rudder is about 3/8 inch.
Start with the bottom rudder hinge and build upwards. The fin extension is then built to suit the rudder installation. The bottom of the rudder should be placed so the the rudder horn (not shown) is level with the center line of the bottom horizontal tube on the fin. The rudder travel stop mounted on the rudder horn will strike a stopper mounted on this tube.
Jan 31,2012: Installed and drilled the axles. Installed the brake calipers. Assembled the main landing gear wheels and installed. Marked and drilled the mounting holes for the dorsal fin. Sanded the firewall, heater pan, root tube over engine in prep for prime and paint. The picture shows the axel housing taped in place. A 5/8 tube (arrow) in the axle housing holds a laser pointer (circled) which allows the axle shaft to be aligned with the gear leg on the opposite side. The laser is pointed just behind the center line of the other gear leg. The starter drill hole for the 1/4 inch AN4 bolt to hold the axel housing is in the square. Drill this hole in 1/64 steps up to 1/4 inch to maintain accuracy and avoid breaking a drill bit.
The axle shaft has been installed with the key way facing up. The 3/16 hole has been drilled on the inboard side of the housing to hold the axle in place and the bolt installed The hydraulic brake caliper is now mounted on the axle. There are 2 hidden set screws underneath that must be removed, dabbed with blue Loc-Tite and reinstalled.
The tire can be fitted to the rim assembly by squeezing the outer edges of the tire to force the inner edges outward on to the rim. I use ratcheting straps. The inner edges of the tire and the rim should first be lubricated with some light oil to facilitate the rubber sliding over the metal. Then fill the tire with air and, if you have a fairly good tire to rim seal, the tire will slide onto the rim with a loud pop. There are a lot of forces involved so the 6 bolts holding the rim together should all be fastened down tight for this process. The assembly area and the rim parts should be kept clean to avoid metal filings or dirt from causing air leaks in the assembly.
The main landing gear wheel and brake assembly temporarily installed. The tire is inflated to 25 psi. The assembly will later be fitted with the wheel pant and the gear shaft with the streamlined cover. So the axle nut is not tightened down yet.
Feb 6,2012: Masked off the fuselage for painting the engine mount root tube, firewall and heater pan, and the cockpit area tubes. Sanded and cleaned tubes with MEK. Blew out dirt and metal chips with blow gun. Primed the metal with galvanized metal primer.
Also cleaned up my shop in the basement and unpacked the Rotax 582 engine and put it up on the work bench. Now ready to invert and install the hoses and brackets.
Feb 7, 2012: Painted cockpit tubes. Started the 582 engine conversion. Cut the motor mount casting. Cut and fitted the cover plate. Removed the pull start assembly and installed the electric starter motor.
The Rotax 582 engine with the GPL electric starter motor installed where the pull start used to be.
Feb 10,2012: Assembled nose wheel and then installed the nose gear assembly. Installed the rudder pedal push rods. Fabricated an electrical box for the fuse block and the power bar. Installed mounting support angles for the electrical box. Installed 5 terminal strips on the avionics shelf.
Feb 12, 2012: Started engine conversion to inverted position. Moved slide valve oil reservoir. Installed exhaust manifold. Installed one coolant hose for running up to radiator.
Feb 13, 2012: Continued engine conversion. Installed EGT, CHT, and coolant temperature sensors and spark plugs. Installed fuel pump, carburetors and fuel lines. Installed heater assembled and air hoses into fuselage.
The carburetors and fuel pump installed.
The heater installed in the heater pan below the engine area with forced air hoses installed and running up to the cockpit area.
Feb 14, 2012: Fabricated top cover for electrical box. Wired up the heater. Wired up the wires from the engine sensors to the terminal strips on the avionics shelf and labelled them. Sprayed primer on the door frames, electrical box and its support brackets. Drilled holes for the strut brackets in the horizontal stabilizers.
Feb 15, 2012: Painted the electrical box and its support frame and the ceiling frame. Installed the nose cone, cut the hole for the nose wheel shaft, and drilled the mounting holes. Installed the sheet metal blending strips for the nose cone. Installed the shoulder belts. Installed the wing spar Rony brackets to the root tube. Installed the electrical box on its support frame in the nose. Trial fitted a cardboard pattern of the instrument panel. Laid out the instruments on the panel pattern.
A cardboard pattern of the instrument panel is fitted. It is going to be a large full panel so theis design will maximize available space but also will leave room for tall pilot.
The instruments are laid out on the cardboard pattern to check for fit.
The sheet metal pieces that blend the flat side of the fuselage to the curved side of the nose cone.
Feb 17, 2012: Did some more wiring in the battery compartment, electrical box and the avionics shelf.
Feb 18, 2012: Installed the transponder antenna on a lexan sheet on the cockpit floor. Cut out a sheet metal ground plane for the antenna and installed. Laid out the cut line for the flip up nose cone.
Feb 20, 2012: Drew the panel layout on a sheet of .090 aluminum and cut the panel outline shape and cut out the switch and instrument holes. Mounted the altitude encoder on the electrical box.
The intrepid builder drilling and cutting out the holes for the switches and instruments on the aluminum sheet that will make up the instrument panel. Note the grim determination on his face. Note also the safety glasses and hearing protectors. It’s a noisy business with lots of flying metal bits.
The sheet aluminum instrument panel after an hour or so of drilling and cutting with hole saws.
Feb21, 2012: Fitted the gauges and other components to the instrument panel. Fitted the panel to the cockpit and made up mounting brackets. Sanded and primed.
The mounting brackets are fitted with anti-vibration threaded mounts to protect the expensive avionics and gauges from the vibrations and bumps that will be encountered in service. these mounts are bolted to the 1″ diameter 2FB-1 vertical fuselage brace tubes with 3/16 AN bolts. A fifth vibration mount at the top of the panel provides additional stability to the panel.
Feb 22,2012: Painted instrument panel semi-gloss black. Began assembling the radiator louver assembly. Filed of the sharp corners. Laid out the louvers on the top panel.
Feb 23, 2012: Continued radiator louver assembly with Clecos and then disassembled and sanded in prep for priming and sanding.
Feb 24, 2012: Primed and painted radiator parts.
Feb 25, 2012: Assembled radiator.
Feb 27, 2012: Installed instruments into panel and installed panel into cockpit. Wired up the switches and gauges. The ignition switch is back ordered hence the open hole. The radio has not arrived yet and that hole (left of the transponder) is temporarily filled with a tachometer.
Feb 28,2012: Wired up the intercom and transponder. Installed Push to Talk (PTT) switches in control sticks. Installed hydraulic brake lever on front control stick.
Feb 29, 2012: Finished the wiring. Installed headphone and microphone jacks and soldered them and ran the wires to the intercom terminal strip.
March 1,2012: Safety wired the turn buckles on the control sticks. Fabricated throttle quadrant mounting plates front and rear. Ran hydraulic lines for brakes along torque tube and gear legs. Ran strobe light and fuel sender wires and installed terminal strips for these.
The fuel sender wires are run back from the gauge to the rear of the aircraft into the mid fuselage compartment. Here a terminal strip will make connecting the wires from the tanks quick and easy.
March 2, 2012: Filed and sanded mounting plates for throttle quadrants and then primed and painted these. Installed throttle cables through airframe and firewall. Fabricated elevator push rods. Drilled holes in tail pieces for fabric rivets.
March 4, 2012: Installed throttle quadrants and connected cables. Installed flaperon control handle and push rod. The flaperon handle is mounted on the left side of the root tube and forward of the wing spar for ease of use during flight. I painted it blue to stand out. That looks nicer than the bare metal.
The throttle quadrant from Light Engine Services installed. It combines the lever for the throttle and the lever for the chokes into one nice attractive package. It features a friction adjusting knob and an adjustable throttle travel limit. I paint the throttle knobs green and the choke knob yellow to finish the look.
March 5, 2012: Installed lexan ceiling in cockpit. Filled hydraulic brakes with fluid and bled. (The hydraulic fluid was bled of air – I actually did not cut myself and bleed at all today) Drilled holes in cockpit tubes for fabric rivets to retain Velcro strips for holding upholstery. Installed framework for nose pivot to rotate fuselage when covering and painting. Lubricated the aileron cable pivot points in an effort to free up the side to side stiffness in the control sticks. Finally had to pump oil down the inside of the nylon aileron control cable sheath using the Lake Aviation Control Cable Lubricator. This freed up the movement.
March 6, 2012: Started work on left wing. Fabricated wing root and wing tips boxes and riveted the bottom sheet of both boxes. Installed wing root webbing. Started installation of top wing ribs and leading edge wrap.
March7,8,9, 2012: Drilled ribs for fabric rivets. Drilled and files W1X and W1XX wing rib gussets. Cut and fitted leading edge wrap. Installed wing ribs and gussets and riveted in place. Installed webbing on outer wing box. Installed mid reinforcing wing box on wing root. Riveted all the ribs in place. Riveted the wing boxes and webbing. Riveted leading edge wrap in place on wing ribs.
March 11, 2012: Installed C channel leading edge wrap stiffeners. Installed round bottom ribs and riveted. Drilled holes in wing root for wires and fuel line.
March 12, 2012: Installed C channel bottom ribs over compression struts. Installed fiber glass wing tip with Clecoes. Installed rib webbing on sides of fuel tank compartment. Installed fuel tank. Cut inlet and outlet holes. Installed fuel inlet flange and cap.
The fuel tank from the back showing the structural support tubes at the rear of the tank
The wing tip installed with Clecoes. We are awaiting the Nav and Strobe lights to install in the wing tips.
March 13, 2012: Installed fuel inlet flange and outlet fitting in the right wing tank. Installed fuel level senders in both tanks. Cut the leading edge wrap for over the fuel tank and installed Installed and riveted the short rib over the fuel tank. Ran the sender wires and fuel line to the wing root.
I added a second 1/2 inch stiffening tube under the fuel tank leading edge wrap 3 inches behind the first stiffener – just in front of the fuel cap – because the leading edge wrap was buckling there and the fuel inlet flange was sticking up over the wrap.
The finished fuel tank assembly from the rear. The sheet metal cover over the tank is an inch longer than what is supplied in the kit. I wanted the holes over the fuel inlet flange and the fuel level sender to be large enough that these items could be removed for maintenance or replacement. A standard inspection cover will be placed over the fuel sender hole. These holes are 3.5 inches in diameter.
The wing root showing the fuel line and fuel sender wires emerging from the wing. The holes cut in the wing root sheet aluminum webbing are to enable a hand to reach in to pull fuel line through in the future for easy fuel line replacement (every 5 years).
March 19,2012: Cut nose cone for Flip-Up Nose Cone Mod. Painted Mold Release Compound on Front Section and then applied fiberglass to the inside of the nose cone to make a flange along the cut line. The picture shows the wet fiberglass sheet encased in plastic poly sheet. This technique keeps the task much less messy. It allows you to carry the wet fiberglass and lay it down in place without getting it all over yourself and everything else in sight.
March 20, 2012: Uncoupled the nose cone halves. Reinforced the fiberglass in some places where it was a little thin. Started the right wing assembly. Installed all the bottom ribs and fabricated the bottom of the wing root and wing tip boxes. The picture shows a length of angle aluminum lying across the bottom ribs. This allows the builder to ensure that the “C” Channel ribs that go over the compression struts are installed at the same level as the round ribs. The C channel is held in place with C clamps and then riveted in place.
March 22,2012: Trimmed nose cone fiberglass flange to 1-1/2″. Installed the flip up nose cone hinge assembly. Put the nose cone on the plane and tested the function of the hinge.
March 26, 2012: Sanded the nose cone, cleaned it and then sprayed it with 3 coats of primer. Yes, there are 2 nose cones. The second one is for a repair on another aircraft.
March 27, 2012: Built the wing root and wing tip boxes and riveted them together. Used lots of Cleco fasteners! Note: leave the inside rib Clecoed, not riveted yet, as the leading edge wrap must fit over that rib
March 28, 2012: Installed wing tip webbing. Installed the top wing ribs and the leading edge wrap. Drilled all the gussets. Riveted it all together.
March 30, 2012: Painted nose cone 2 coats of white paint.
April 2, 2012: Right wing work continues. Installed C-channel stiffeners under the leading edge wrap. Installed fuel tank rib webbing. Then installed the fuel tank and ran the fuel line and the fuel level sender wires to the wing root. Installed the wing tip with Clecoes.
April 3, 2012: Installed leading edge wrap over the fuel tank. Installed the short rib behind the wrap. Installed the Kuntzleman Strobe / Nav lights in both wing tips and ran the wires to the wing root.
The wing tip lights combine the Nav lights and Strobe lights in one streamlined package. Kuntzleman part # DDM-SLC Combo unit.
April 6, 2012: Fabricated bottom (winter) louvers for radiator. Installed a fuel drain valve in the low point of the fuel system. Installed Velcro to close door on small storage compartment. Pictured is the drain valve taken from below the rear seat. This will allow a fuel sample to be taken at the lowest point in the system where water is most likely to gather.
April 9, 2012: Ordered the Primer and paint and other needed covering and painting supplies. Ran wires for the optional electrical elevator trim tab. Installed Push to Intercom switches for both seats.
April 10, 2012: Drilled holes for fabric rivets to retain velcro for upholstery in cockpit area.
April 16, 2012: Machined the motor mounts and then sanded and primed them. Mounted the driver box for the Kuntzleman Strobe lights on the back wall of the small storage compartment. Assembled the Molex terminals on the strobe wires. Mounted the radiator louver control lever in the cockpit ceiling and then sanded and primed it.
April 17, 2012: Painted the motor mounts. Sanded and primed the elevator and rudder horns. De-greased and sanded the rudder and the dorsal fin. Added anti-chafing tape and covered them with fabric.
April 18, 2012: Painted the tail booms and the elevator and rudder horns. Covered the fin and the horizontal stabilizers. In the picture the stabilizer has been covered, glued down and then ironed. The sheet over the bench keeps the fabric clean and prevents the fabric from being snagged and torn on sharp corners.
April 23, 2012: Assembled the pivot stands. Sanded the fuselage and degreased with MEK. Added anti-chafing tape. Covered the bottom with fabric, trimmed and glued, and ironed in three stages to 350 degrees F. In the picture the fuselage is mounted on pivots so it is easy to work on the belly. The blue boxes are placed under the fuselage just in case the pivot bolts break. Its very unnerving seeing the fuselage on its side like this!
The belly fabric is hung on the belly with clips, glued down to hold it and the extra fabric cut away. Holes are cut for the fuel drain tube and the transponder antenna. Then the edges are trimmed close and the edges all glued down. The fuselage can be pivoted around to work on the right edge and then the left. Very handy!
With the glue all in place and the edges trimmed and glued down, the belly can be ironed and the fabric shrunk tight. All the wrinkles disappear.
The aircraft back upright and ready for covering the sides of the fuselage.
April 23/24, 2012: Covered fuselage with fabric. Started with the left side. First hung the fabric.
Then glued down the fabric starting with the angle area just behind the engine former tubes. Then worked forward around the formers. Then back toward the tail along the spine.
Glue the top first and work down to the belly. Trim the edges of the fabric with pinking sheers and glue them down.
Let the glue dry, then shrink starting at the area below the engine former tubes. It always amazes me how this baggy area tightens up.
Then over to the right side. Hang the fabric. Glue it down carefully. Trim the edges and glue them down. Iron it out.
Iron first at 250 degrees F, then 300, then 350.
April 27, 2012: Covered the mid fuselage access doors with fabric. Burned holes in the fabric with a hot knife for all the bolt and rivet holes that were covered over.
April 30, 2012: Sealed the fuselage fabric with the first brushed on coat of Poly Brush and applied fabric tapes to edges, corners, and other key areas.
May 1 and 3, 2012: Installed Fin and dorsal fin. Installed rudder. Riveted and taped tail ribs. Taped the rudder gap. Installed fin to dorsal sheet metal blending piece. Flatted down pinked edges and smeared out glue blobs and runs with iron at 225.
May 4, 2012: Finished taping the tail area. Taped dorsal fin gaps. Taped fin and rudder edges. The runs seen on the fabric are actually on the inside of the fabric and will not show after priming and painting.
May 7, 2012: Masked fuselage in preparation for spraying. Carefully checked that any loose fabric was ironed down. Smeared off any glue blobs with the iron at 225 degrees F.
May 8, 2012: Sprayed 2 cross coats of Poly Brush onto the fabric. This seals the weave of the fabric. It becomes a salmon or orange colour. The fabric will have a slight sheen to it from the coat of Poly Brush glue now covering it.
May 9, 2012: Sprayed 2 cross coats of Poly Spray UV primer on to the fuselage fabric. The pink area behind the engine former tubes is left un-coated because I noticed I needed to add some reinforcing tape there.
May 10, 2012: Sprayed another cross coat of Poly Spray.
May 11, 2012: Sprayed another cross coat of Poly Spray.
May 14, 2012: Sprayed 2 cross coats of white Poly Tone paint on the fuselage. This picture shows the first pass off paint spray done on a 45 degree angle to the left. You can see the tiger striping effect off the spray pattern. This is the first half of a cross coat. A cross coat is two separate passes with the spray gun. The second pass is down at 90 degrees to the first. These initial spray coats are not glossy. They are simply to add base material to the fabric to cover over the grey primer. The sprayer is set at a lighter spray setting than what will be used for the final wet gloss coat.
This is after the second pass with the spray gun now moving at 45 degrees to the right. You can see the X pattern on the fabric. This completes the first cross coat. We let this dry for 2 hours and then do another cross coat. We can only do a maximum of 2 cross coats per day.
This is after the second cross coat. For this cross coat I did a horizontal side to side pass with the spray gun and then came back and did a vertical up and down pass with the sprayer. The effect of using these two types of cross coats is shown in that the paint coverage is complete. A little bit of grey shows through still but you have to get up close to see it.