When Mark Langford came up with a
canopy hinge retrofit, I
was pumped!
I had problem with the side hinge on N5391M. The screw heads were pulling through the installation holes. To compound the issue, the screws in the canopy frame were wet mounted in flox; removing them was an exercise in futility.
I tried to guess Mark's construction methods and came up short
on the amount and type of carbon fibre he used to build the hinge blanks. I used
the only carbon I had and a 10 layer laminate only measured out to .112”, a long
ways from the .250 thickness dimension Mark cited on his site. As true to his
form, Mark responded with answers and part numbers when required. That made an
order for additional materials easier.
I ended up with 15 additional layers plus 4 doubler-layers
at the pivot point to gain the required stiffness. Mark did a great job of
documenting the basic process.
I reverse-engineered this from Mark’s photos of his hinge blanks that looked to me about 15” long with about 4” bonded to the canopy frame. My blanks ended up just a bit longer at 16”.
Mark cited a problem where he had to clearance the hinge blanks around the curved sides of his installation. I followed his recommendation and built the pivot brackets Mark designed about ½” taller and mounted them on top of the longerons with the pivot about 18” aft of the firewall.
I aligned the pivot brackets using the 4’ long 3/16” rod
used for aligning the tail feather hinges. Remember all the way back then in
your construction sequence when you mounted those hinges? I used the #8 screw
Mark recommended to lock the brackets into place. I countersunk the machine
screws to maximize clearance for the bushings.
I think no 2 KRs are built exactly alike. N5391M has a
removable forward deck/ fuel tank assembly. My canopy frame has an aft stiffener
bow of ¼” plyfoam bonded into place with a single strip of carbon. This
increases the overall rigidity of the frame considerably and I think it makes
the structure better suited for the hinge retrofit.
I am awaiting delivery of the gas springs. Well, that and a
new condition inspection!