Willie,
Aileron hinge wear in 10 year old aircraft never lubed is common. Most
civil aircraft pilots never look at the hinges, as a mechanic or A&P, over
here in the US, are supposed to know the wear limits, and trust that the
civil authorities will keep their aircraft safe, however to be frank, there
are no limits published. If the hinge pin is worn, a good mechanic will look
at a new hinge gap movement, then note the limit they feel is safe.
However, in experimental aircraft, most guys don't trust the aircraft and
are really concerned as it was built by an amateur.
That said, normally a 10 year old 1000 hour aircraft which has been hangared
has hinge pin wear of about .015 more than new which is about .013 inches so
a total slop of nearly .03 inches.
Wear of the aileron hinges above is rare in my experience. However, I have
seen a number of aircraft that have been built with misaligned hinges or
have an aileron and wing misfit. By misfit I mean that the wing tip curves
up but the aileron is straight. The builder builds his hinges flat on the
aileron and then the bow of the wing to aileron causes the hinges to be
under a slight bending load. This is evident prior to finishing when the
aileron has what feels like a spring in it as the fiberglass is the spring.
This causes the hinge to wear quickly. In this case, the hinges must be
removed and the aileron and hinge properly aligned.
Removing a hinge is a fairly short job:
1. Remove the aileron.
2. Check hinge alignment with an angle stock sufficiently long enough and
check the the hinge alignment on the aileron and on the wing. Shimming the
wing hinge bed may be necessary to assure hinge alignment. Shimming must be
done to keep the hinge pins straight regardless of the bow of the wing.
Normally, we tape up the hinges with release tape then make a bed of Redux
to make a bed and assure a straight hinge line. If the tip of the aileron
bows away from the wing, we fill the wing.
3. Prepare to remove the hinges by removing the paint from the inside of
the aileron hinge top and surrounding reinforcing layups. Note the rivets
position in relation to the aileron foam and glass so you don't damage the
aileron structure.
4. Using a 4 inch thin cutting disk on an air grinder I lay the grinder on
the hinge being careful to only cut off the rivets and impact the hinge,
not the glass or foam.
Note: The grinding action heats the rivets and loosens the epoxy while also
cutting the rivet tail off. This also cuts the hard metal rivet stem off
making the rivet easy to drill. This heating will generally expose the
rivet heads which are countersunk, and filled with filler making them easy
to see.
5. Using a countersink (119 degree non post type) in a slow drill, cut the
rivet head off, or just drill out the rivet with an 1/8 inch bit. The
drilling and grinding will loosen the rivet head for you.
6. Gently pry the hinge to see if the heating has loosened the hinge from
the aileron inner skin. If it hasn't loosened the hinge, either use the
grinder on the hinge to heat it or a 40 watt soldering gun to heat the
aileron hinge only until just too hot to touch. DO NOT USE A HEAT GUN!
Then pry the hinge free of the flox bed it was mounted in.
7. Clean up the glass/flox bed with sanding action by hand or if quite
proficient with power tools, a carbide cutter and an air or electric hand
tool to prep the aileron inner skin. Don't screw up the aileron skin.
8. With the hinge free at last, make a new hinge as close to the original
as possible (providing they are OK). Don't copy the holes just yet.
9. Follow the aileron hinging instructions in the build manual to align and
set the aileron hinge to the aileron.
Note: Pay attention to the hinge alignment. You must also be careful in
your hinge alignment to allow you to use the previous rivet holes in the
wings in new aileron hinge and still maintain hinge edge distance. If in
doubt make the hinge longer. When all is well, rivet it home.
10. Once the hinges are on the aileron, set the aileron into the rebate and
check it is in the same position. If all looks well on the position, gap
and rebate, then mark it. The wing hinge side is flopping around, so prep
your hinge with a lump of clay to hold the hinge out in position. Next,
"offer" the aileron up to the wing again, and carefully mark one of the
screw holes for drilling on each hinge. Once the one hole is marked, remove
the aileron and drill the one hole in each hinge to 3/16 inch. Offer the
aileron up again and fit with a 3/16 inch cleco to hold. Try the aileron in
place and check alignment. If all is well, remove the aileron again (yes,
if you haven't put it together and taken it apart at least 5 times, your
screwing up), then apply a dab of 5 minute glue, contact cement, or super
glue to the wing side hinge, and cleco it up again. Allow to cure. Check
the movement, and if all is well, drill and cleco the remaining holes.
When all the holes are drilled, crack the aileron hinge loose.
11. Nut plate the screw holes in the hinge (making sure to countersink the
PROPER SIDE), then install.
12. Only a small amount of paint and filler is necessary over the
countersunk rivets...
Typically it takes a day or two to finish the task.
Best Regards,
Bud Yerly
Custom Flight Creations, Inc.
-----Original Message-----
From: William John Harrison
Sent: Saturday, May 30, 2015 3:32 AM
Subject: Europa aileron hinge replacement
Dear Bud
Steve Pitt suggested I email you. I am a Europa owner in the UK. My
aircraft, which has approx 500 hours (and 12 years) since new, has developed
severe wear on both outboard aileron hinges. They need to be replaced. The
inboard hinges are fine and this problem has developed progressively over
the past two years.
I wondered if you could help with two questions:
1. How common is this problem? If it isnt common, then something must have
been wrong with the hinges, or the way they have been lubricated over the
years (lithium aerosol spray every 25 hours).
2. Do you have any experience of changing aileron hinges? Are you able to
offer any advice and guidance about how to do this?
I didnt build the aircraft myself and I have no real skills in composite
layup. However, my inspector (Tony Kay) has said he can help me with this
and he certainly is an expert with composites.
Withe best wishes
Willie
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