Building the Third Door Modification on a Challenger

Designing and building the third door modification on an experimental challenger II light sport aircraft.  Designing and building the door latch Challenger third door mod.

Light Sport Aircraft

Easy entry into the aircraft was a must with some one my size and age.


Challenger Third Door Fabrication and Install  |  Designing The Door Latch

Challenger Third Door Modification

Challenger Wind Screen

Windscreen laid out on the wife's favorite blanket to prevent scratches

Sanding rough edges

Sanding rough edges.  Watch out for possible flash from bald head if the next two pictures are enlarged.

Enlarging 1/8 inch holes

When fitted to plane 1/8 inch holes were drilled.  Enlarging one size bigger to allow for movement in rivets.  Helps prevent cracking

Installing 1/2 inch tubing

Installing 1/2 inch tubing for third door.  Tubing is easily bent to the contour of the windscreen from the outside.  Then cleco in place on the inside.

Tubing bent and clecoed

All 1/2" tubing bent and clecoed in place

Top portion of install

View at the center cap.  The windscreen is attached to a 1/2" tube bent the shape of the center cap.

Jig used to bend tubing

Gussets photographed on the jib used to bend all the tubing.

Hinges cut to 5 inches

Hinges cut from a 6 ft. piece of piano hinge.  Hinge length is 5"

Challenger windscreen hinges fitted

Cutting windscreen just far enough to fit hinges. 

Putting it all together

Removing clecos and applying rivets

Removing one cleco at a time to ensure everything stays in place.

Final fitting of third door

Door is temporally mounted for final check before continuing with install.


Designing the door latch

The answer to the problem of latching the door securely came in the Challenger kit. It's part of the regular door kit used to secure the doors in the open position.

Having some of the same material from my wood working days I used the band saw to cut the shape of the top rail.  Drilling through the 1/2" tubing and the gusset the latch is secured.

No other trimming was needed and things fit like a glove over the side rail.

Side rail wear guard

The latch is firmly secured by locking it behind the rib.  It snaps in place and holds just enough tension to slightly bend the Lexan against the side rail.  See previous photo.


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