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Good Morning Steve,
I'd like to have a copy of your towbar plans, just for future use.
I'll stick it in with my other coupe stuff and have it when I need it.
How (and where) did you fasten the flasher lights to the airplane? Bunji
cords, duct tape, string. or ????
As for the end play in the crankshaft, a few years ago I decided
(don't ask me why) that I needed to check the 'tracking' of my propeller.
I removed one spark plug from each cylinder so I wouldn't have to fight
the compression and the prop would stay exactly where I put it. (I also
removed the remaining mag leads from the other plugs.....just in case the
mag grounding switch might 'malfunction'.)
I placed a white plastic 5 gallon bucket (inverted for stability) on
the ground just forward of the prop. Then I turned the prop until one
blade just, 'very lightly' touched the bucket but didn't make the bucket
move even the slightest amount. Then I turned the prop 1/2 rotaion until
the opposite blade was at the bucket. I was amazed that there was about
3/16 of an inch space between the prop and the bucket!
I then rotated the prop another 1/2 turn to get back to the original
blade so I could double check it. I knew I hadn't bumped the bucket with
my foot but something just didn't make sence to my finely tuned
'horse-sense'. Now that blade was also missing the bucket. After doiing
this a couple of times I realized that the crankshaft had some 'endplay'
in it and when I rotated the prop I was also moving the prop either
forward or backward and the distance between the blade and the bucket was
moving a corresponding amount.
Now I switched on the 'horse sense' button. Push the prop all the
way back and check the first blade......turn the prop to the second blade
and push the prop all the way back. Wow! What a difference this made!
It was 'out of track just a tiny bit so I removed the prop from the plane
and made a spacer from a page of yellow 'legal pad' paper. I cut the
spacer into two pieces (like slicing a pie or cake in half) with a pair of
scissors, being careful to make the cuts exactly centered between the
mounting holes on opposite sides. At first I put both 'half circle
spacers' on the same side. This was to much so I removed one thickness
and then the prop gently touched the bucket with both blades.
After torquing the prop bolts I re-checked the tracking and it was as
nearly perfect as a 'horse sense' mechanic can get it.
I have my prop removed right now and it's in the prop shop for
complete inspection and repainting. When I get it back I plan on using
the above method to check/adjust the tracking again.
BTW, did you know that a 'polished' prop (unless it left the factory
that way is grounds for 'grounding' the plane in the case of a 'ramp
check'? It's considered an 'unauthorized' modification and if there's no
337, or what ever, in the logbooks showing that a propellor shop modified
it, then it's not legal.
The guy who runs the prop shop here in my city told me about this as I
was going to have him polish it for me instead of painting it. He said he
has a friend that flies airliners for a living. He flies his personal
plane to the big airport and leaves it there while he flies his route and
then flies his own plane home again upon his return.
Once when he returned from his route and went to his own plane he
discovered that it had been 'grounded' by a ramp check while he was gone
as well as one other plane that was 'based' at that airport. Both for
having polished props!
My prop man told me that he would polish it for me if I insisted (I
told him I really wanted it polished) but he would not do any paperwork
on the prop showing that he had ever worked on it. The best part of this
conversation was that he took the time to tell me (and show me) some of
the other props he had in his shop with 'deep' corrosion on the prop
blades and they were so deep that they were no longer airworthy.
Mine was already silver in color but not 'highly polished'. He
removed the manufacturers sticker from one blade and showed me the
difference in the surfaces. Under the sticker there was no sign of
corrosion but the rest of the blade was, upon close examination, full of
very tiny pits of corrosion. He told me that if he removed all the pits to
make it smooth again he thought he could save it this time, but there
wouldn't be enough thickness left to allow him to overhaul it and make it
legal again someday in the future. If he, however, is going to paint it,
he can die check it, acid (or something) dip it to remove all the
corrosion and then the paint will fill in the holes to prevent further
corrosion so the blades will still be thick enough to allow me to get it
overhauled one more time if I ever need to. I told him to repair it,
overhaul it, die-inspect it for any interal cracks, and then paint it. (He
showed me some prices on new props....Nearly as much as I spent for my
Ercoupe when I bought!
During our conversation a guy came in that works in the next hangar.
My prop man told me that he was the only person he knows who lived through
'losing a blade' while in flight. Can you imagine the vibration if the end
of one blade detaches during flight??? I'm surprised it didn't shake the
whole engine off of the plane. Those four little engine mount bolts must
be awfully strong for their size, or else he has the worlds quickest
reaction time to get the mag switch turned off!!!
He showed me how much my prop was 'out of balance' when I first took
it in. Not a lot really, but enough to make a noticable vibration. The
conversation went on from there until I decided to spend the extra bucks
and do the job right. I'm also going to be inspecting my engine mounts
very closely for any signs of loose, worn, or cracking caused by the 'out
of balance' vibration.
I didn't mean to turn this into a 'novel', but it seems like that's
the way it turned out.
Bob Savillle
N3396H 415C
Eugene, OR
Steven Finkelman wrote:
----[Please read http://ercoupers.com/disclaimer.htm before following any
advice in this forum.]----
I am in the midst of pulling my engine to do some majorwork on it for the
first time in about 15 years. I removed the wings and trailered them
home...and last weekendI brought the rest of the coupe. I have a tow-bar
made of perforatedangled steel (like the stuff for shelving units) that I
made many years ago,and have used about four or five times. It works just
like a tow bar youpush the plane around with. It locks into position, and
there is a threadedrod to clamp the bar in place on the nose wheel. I
added some home-made flashing warning lights with some margarine
containers, a couple ofred lenses, some auto bulbs and a flasher. I wired
this into the tail lightso I could run it off the coupe battery sparing me
long trailer wires. FinallyI turned my belly strobe, turned on the
four-ways on the truck andproceeded to tow the coupe home (about 40
kilometres--25 miles) downa four lane highway and into the city. I had to
keep it under about 37 k/hrabout 25 mph, but it worked fine. By the way
there is no corrosion on the spar at all. The last time I had ithome,
about six years ago, I redid the fuel tanks in the wings andcleaned and
zinc chromated everything I could reach. The wings, aftersitting outside
all this time, are still perfect. Alberta is blessed withdry conditions so
corrosion is not usually a problem until you really abusethings. One
question. As I dismantle the engine compartment I noticed
someforward/rearward play in the crank shaft. Is any play allowed? Is this
an indication that the bottom end has gone to Ratshit like the top
end...or isit just worn bearnings. Just wondering what I will find when we
get it open?? Steve FinkelmanForney F1C-FIWR p.s. If anyone wants a jpeg
of the towbar...I can send one.
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