Further to my remarks regarding access door hinge pins: what I believe I
have learned.
I hope the pictures (ancient 2002 digital camera) make it a bit more
clear than last time.
1 To remove all excuse for not opening an access door before flight I
provide the door with a hinge and a quarter turn dzus fastener with a
winged stud for finger operation.
2 Planning
- In closed condition the fastener stud wing and the fastener receptacle
have parallel long dimensions; to be able to mount
the receptacle along the hole edge and have the stud wing parallel to
the wind in flight the hinge should also be mounted
parallel to the wind. I did differently and will suffer (I will make a
right angle receptacle as soon as I acquire a choice of
spring steel wire).
- If in sandwich skin: determine the contours - from inside to outside
(picture): line 1 door sandwich to door flange, line 2
hole outline, line 3 door outline, line 4 glass-glass flange to
sandwich; beware the room needed for hinge flanges (see 4 and
5 below) and the fastener receptacle
3 Making
- Remove the inner skin and foam with router bit and sandpaper between
lines 1 and 4, fair the edges
- 2 bid between lines 1 and 4, overlapping, and well overlapping the
foam outside line 4, peel ply
- Cut out the door along line 3, then tape up for release, then put in
place and tape flush with the fuselage outside skin
- 2 bid between lines 1 and 4, well overlapping the foam outside 4, peel ply
- File and sand the flange produced (for the door to sit against) to
size and shape
4 More planning
- The hinge line must be outside line 3 for the access door to open well
- The hinge flanges need flox beds for the hinges to end up flush with
the outer skin
- The hinge pin cannot be put in and taken out without surgery unless
cut up in pieces in advance
5 More making
- Make the hinge with a sectioned hinge pin and holes each end for a
cotter pin or safety wire
- Remove the flange between 2 and 3 and a little out towards 4 where the
outer hinge flange will be; leave the door (inside
line 3) alone
- Put the hinge together with greased moving parts, position, apply flox
beds, and apply pop rivets when cured
6 Check
- Displacing the hinge pin sections 1/4" should now release the door easily
Jan de Jong
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