Alan, and others:
I have an 8 year old aircraft as many of you do, with many small cracks
chips and dings in my finish. What is good and what is bad requires
inspection. Builders are more aware of the amount of filler on their
aircraft and can easily tell if the crack is in the finishing material or
structure. Note that gel coat tends not to crack but the filler certainly
does. That said, impact damage can show as a spider crack in the finish
where the urethane paint fails as well as the gelcoat. Blisters and
de-laminations are to be attended to immediately.
As a builder I am the manufacturer, and am responsible for my checklists,
ops procedures, determining go no go, equipment lists etc. Second hand
owners must secure a knowledgeable aviation mechanic to determine the
condition of the aircraft. As a pilot, It is my job to do a proper
preflight, system and control checks as we did as professional pilots. As a
second hand owner, you are not normally a qualified maintainer so asking
questions is the right thing to do. Comprehensive lists of wear items on an
airplane means some company has done extensive mean time between failure and
ISO tests to determine life spans of components. You will NEVER get that in
experimental or general aviation. If the mechanic says its OK, and you
don't think so, don't fly was our rule as commercial pilots. As an airplane
owner you should be aware of ADs, SBs, SIs, and Mods affecting your aircraft
to alert your mechanic.
Typically I see the following:
Cracks around the door sill area created by pushing hard on the sill on
entry and exit. (Solved by putting in a diagonal from the sill to the side
making a triangle.
Cracks in Trigears where our butts sit on the wing forward of the spar.
This crack radiates along the spar from the wing fillet to the first rib and
is in the filler that is along the transition between the solid spar and
flexible skin. This is an area never intended as a heavy duty walkway.
(Solved by carbon fiber or glass over the filler from the root rib to the
1st rib to prevent flex cracking.)
Cracks around tail tie down not properly reinforced or impact damage from
nose high tail dragging landings.
Cracks in the rudder lower hinges due to smacking the stops. (The filler is
thick here often times and it can't take flexing without cracking.)
Cracks at the aileron hinge from full deflection aileron rolls (mild
aerobatics). (Inspect after aileron removal for white line crack. If so
reinforce, both sides and repaint.)
I do not normally see cracks in the wing through hole area.
Most new owners abuse the wing sockets thinking they hold the wing during
rigging. They are a guide and alignment device, have your assistant hold
the wing tip until the pins are in. Do not slide the spar on the raw glass
of the hole, it will cut the glass. Install a stainless or phenolic sheet
to protect the glass. There should be no cracks in the wing box area or
spar strap.
Aircraft with hard landing impacts or overstressing will show some skin
bending in the wing area between the forward and aft pins and spar hole. If
the area is wrinkled or cracked, do a proper hard landing inspection. Buy
some touchup paint for sure if you have cracks as you may be grinding some.
Most new owners screw up the stabs because they were never taught how to
properly put on a stab and take it off. It amazes me that they grab the tip
and just pull and wiggle. That's a broken out bearing waiting to happen.
Refer to the operators manual drawing on the figure installing the
tailplane. Do it vertical, but the hands are in the wrong position. The
lower hand should be able to balance the stab vertical and the upper hand is
used to fine tune and rotate fore and aft to wiggle the tight tube without
any bending on to the torque tube. Slide the stab inboard until the inner
bearing lightly contacts the tube and finesse it on the tube as you did the
outer. Hold vertical and slide the stab inboard until the skin is just
short of the forward drive pin. Rotate the stab short of horizontal and
align the pins with the holes. I move to the tip of the stab and by feel
and eye can hit my stab holes easily then just a bit of a push to put it on
to just contact position, insert your trim tab to the cross tube and then
push on the tip to fully seat the pins in the sockets. To remove, tilt the
stab TE up, use the thumb against the fin and at the fingers cushioning the
root flange with the other hand doing the same on the leading edge and
simply push your thumbs against the fuselage. The stab should pop out a
bit, ease it back, disconnect the tab and use the same hand positions as
installing, while easing it off.
Wear and tear are standard in aviation. Get a good mechanic and spend the
time / money to investigate, and repair.
All the talk about hinge wear means the pilot/builder/mechanic has not lubed
the hinges consistently and there is some corrosion wearing the pin/hole
which is fair wear and tear. This is not a big problem. Look at a 10 year
old Piper and see how much the hinge pins move.
Solution is first to look at a new MS20001 series hinge and see how much
movement there is (+.007-.010 brand new). There is quite a bit, or down
right sloppy movement. Pin tolerance is .003 and has .003 anodizing and
hole tolerance is .007 so seeing .013 wiggle after the anodizing wears off
would not be uncommon. That is a lot. If you have 50% more than that, I
would consider the down time and cut out the hinge and replace. This
happens in all airplanes. People normally don't care on a civil airplane, a
mechanic is required to check it, but on an experimental, they look for
fault. The fault is these items do corrode (pins are steel or stainless,
the hinge is aluminum and dissimilar metals corrode) and wear. Hinges are
under smallish shear loads and a bit in normal force loads so I worry if I
can pull the hinge back and see 1/4 of the hole. Now that's bad.
Bushings wear, bearings wear, paint wears, tubing wears. Fuel/oil line
hardens (even teflon) and one bend makes a micro crack. Nothing lasts
forever.
I do a 25 hour progressive inspection of my aircraft at each oil change. I
start by reviewing my squawk list. What can I fix. While the oil is
draining, I pull and lube the stab tubes, lube all the hinges, the throttle
pivots, and door shoot bolts/hinges. I use a syringe with a large non
pointed tip, and Mouse Milk light oil. Pop open the aft inspection plates
and do a quick look over. Pull the fuel access panels and look for leaks.
Look for tracks of coolant, brake fluid or oil. (My 914 lubricates the left
gear leg and belly well when it sits quite a while and is nasty, so I clean
it up.) Flip up my wheel ts and look over my pads, brake lines, bearings
and service the tires. I roll the plane fore and aft and check my bearings
are not spinning on the axle. (Customers fly my planes and it gets hard use
at times.)
At 100 hours or annual, I fly the aircraft and write down everything for the
squawk list that is wrong or questionable. Land and wash the plane and go
over the aircraft and engine Mod/SB/SI list with a fine eye. Pull the cowl
and all the inspection panels off and inspect carefully. Clean the fuel
system, change the expendables (plugs, filters, drain fuel, wings and lube
every MW bearing, check the torque seal on every bolt, pull the wheels,
inspect and repack the wheel bearings while reviewing my personal
manufacturers condition inspection checklist I created for my plane.
My 100 hour inspection info is on my techniques page, feel free to modify it
to your aircrafts particular needs. However, in a second hand aircraft,
your mechanic may have other items he is keen on checking for his go no go
items. Work with your mechanic and set your inspection interval and go no
go wear limits as I have. Everyone's standards are different.. I could
care less about a spar cup being sloppy, but am hard over about stab torque
tube pins allowing the stabs to move independently of each other over 1/4
inch at the TE or with the TE up and the mass balance just touching, I push
up lightly and check if the inner pins allow movement. Cracks should be
investigated always. Scrape away the sides and look at the glass. If it's
OK fine, or fill sand and paint. At 5 years rip out the hoses, replace
wheel bearings, and brake pads, recondition disks, check the calipers for
corrosion of the pucks, etc. Look up your engine, airframe parts and make a
list of everything you are worried about and increase your inspection time
frame if you need to. Then fix it properly. If you fix everything It will
be like flying a new plane every day. If you choose to do the minimum
amount of maintenance, the plane will deliver the minimum. I still haven't
added options/upgrades I have wanted from 8 years ago. It seems working on
clients aircraft defeats my zest for experimentation on my own.
Enjoy your aircraft.
Regards,
Bud Yerly
-----Original Message-----
From: Alan Carter
Sent: Thursday, April 09, 2015 2:42 PM
Subject: Europa-List: Re: Nose Wheel Bearing
Hi Bud,
Change of topic, I am not a builder but I look closely how things are made,
and I will say I think I could have made a better job of some design
components.
I have 25000 hour and are not going to damage anyone's aeroplane by giving
it a little wiggle, which I have found a number of common wear and tear,
just little things like the wear In the stablator hinges, and plastic cups
on the control arm. seems to wear more on the port side.
Wish some one produced a list of common wear in components one could check.
However I have also noticed on a few planes a small hair line crack some
Europa's have it on both sides and some one only one side, running up from
the corner of the fusalarge of wear the spare slides into the fuselage, I
would say it just a crack in the jell coat and of no structural relevants
caused by flexing of the skin,
Have you come across this before.
Regards
Alan
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