In re-reading my post of 19:47:42, I realized in the process of
composition (when I sometimes move things around) I inadvertently
reversed the insertion of some information. That reversal was, in my
opinion, misleading; however unintended. I said:
Position the rubber donut stack securely in a large, well mounted vise
so it is not easily dislodged. You DON'T want to apply force to the
"ears" the mounting bolts go through and you DON'T want such clamping
force applied to any unsupported part of the actual cylinder in which
the piston must travel freely as permanent distortion will likely
result.
Using two pipe wrenches of appropriate size and cloth padded jaws to
clamp on (1) the flange of the attaching end of the piston (supporting
the "ears" through which the mounting bolts go) and (2) the flange on
the oleo cylinder supporting the rubber donut stack (perhaps with a
friend's help) apply rotational force (as if unscrewing a nut from a
bolt) so as to break the piston-cylinder seizure. This MAY distort
the bottom donut spacer, see item #20, Fig. 12 in the Parts Catalog
(if so, and it cannot be straightened, replace it).
The "clamping force" I wished to caution about was the force exerted by
a pipe wrench as it progressively grabs what is between the wrench
jaws, NOT the clamping force of the vise (which only needs to be enough
to keep the assembly immobile while working on it) because it was my
intent that the rotational force of one pipe wrench be largely offset
by the rotational force applied to the other end (by the other wrench).
Accordingly, I should have said:
Position the rubber donut stack securely in a large, well mounted vise.
Using two pipe wrenches of appropriate size and cloth padded jaws to
clamp on (1) the flange of the attaching end of the piston (supporting
the "ears" through which the mounting bolts go) and (2) the flange on
the oleo cylinder supporting the rubber donut stack (perhaps with a
friend's help) apply rotational force (as if unscrewing a nut from a
bolt) so as to break the piston-cylinder seizure. This MAY distort the
bottom donut spacer, see item #20, Fig. 12 in the Parts Catalog (if so,
and it cannot be straightened, replace it).
You DON'T want to apply force to the "ears" the mounting bolts go
through and you DON'T want such clamping force applied to any
unsupported part of the actual cylinder in which the piston must travel
freely as permanent distortion will likely result.
Sorry,
WRB
--
Begin forwarded message:
From: William R. Bayne <[email protected]>
Date: May 23, 2010 19:47:42 CDT
To: [email protected]
Subject: Re: [ercoupe-tech] MLG Problems, long post, Need Help!
Reply-To: [email protected]
Donald,
Before proceeding further, ask yourself these questions:
1. What kind of an owner/mechanic would put spacers on the main
landing gear oleos without servicing the oleos?
2. What kind of mechanic would sign off an annual without inspecting
the main landing gear oleos for proper fluid and operation?
3. What was the date of the last annual on this bird?
4. How long does it take to eject or evaporate fluid from the MLG
oleos and then for them to seize from rust? (Hint...a lot longer than
a year!)
These questions should suggest to you that prior maintenance of your
airplane has been questionable, at best. That, to me, puts associated
paperwork in question as to completeness and accuracy. It might be
prudent (regardless of your finances and personal skills) to find and
hire a competent mechanic to oversee a progressive annual on it as
soon as possible.
≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈≈
What follows is ONLY applicable to Serial numbers 813 and up!
"Pounding and beating" with a "LOT BIGGER" hammer is a traditional
practice of blacksmiths, but such skills of that honorable trade have
little application to proper repair and/or maintenance practices on an
Ercoupe. Unnecessary damage is the likely result.
The same is true (perhaps even more so!) with regard to using a torch
on any part or assembly in or on an airplane. It is so seldom
necessary as to be best left to an expert. Dismounted, in the vise,
OK (with due care). Remember that any brake fluid or hydraulic oil
remaining in an oleo will likely boil out or vaporize given sufficient
heat, with unpredictable and possibly dangerous result.
With reference to the Parts Manual, Fig. 12, to get the oleos off the
plane you need to remove Items 27, 28 and 29. Before proceeding,
liberally soak them with good penetrating oil. There are times when
only force will resolve a problem, but you want to think everything
through so as to reduce that force to the absolute minimum necessary
before proceeding.
It is unlikely Items 27, 28 and 29 are frozen; but if they are, the
shock of periodic light but solid hammer blows assist the lubricant to
penetrate the assembly. Apply with a punch of slightly smaller
diameter to the bolt threaded end (if that is accessible) or any large
flat-ended punch to the rounded "screwdriver end" (apply so as to not
bugger the screwdriver slot).
If the cotter cannot be extracted in the normal manner, cut off the
bent ends of the cotter. Lock a Vise grip onto the loop end and try
to pry out. If still unsuccessful, try to rotate the nut/bolt such
that the cotter hole is vertical. If you can't, cut the loop part of
the cotter off with a sharp chisel (flush with the nut and use a
socket to to rotate the nut/bolt such that the cotter hole is
vertical. Then use a pin punch to drive out the remains of the
cotter.
If it is not then possible to simply remove the nut with the
appropriate wrench, cut the sucker off with a chisel and drive the
bolt out. Replace any part not in perfect condition after removal
(for reasons that should be obvious), and never reuse a cotter pin.
Once the whole oleo is off the plane, position it in the same
orientation it was mounted and squirt penetrating oil into the filler
cap and the upper seam between cylinder and piston every day (several
times) for a week. (Yes, you could have started this soaking while
getting the assembly off the plane ;<) Then (and ONLY then) attempt
to disassemble each oleo. As Paul pointed out, it may be that your
oleos cannot be saved; but I would try.
Position the rubber donut stack securely in a large, well mounted vise
so it is not easily dislodged. You DON'T want to apply force to the
"ears" the mounting bolts go through and you DON'T want such clamping
force applied to any unsupported part of the actual cylinder in which
the piston must travel freely as permanent distortion will likely
result.
Using two pipe wrenches of appropriate size and cloth padded jaws to
clamp on (1) the flange of the attaching end of the piston (supporting
the "ears" through which the mounting bolts go) and (2) the flange on
the oleo cylinder supporting the rubber donut stack (perhaps with a
friend's help) apply rotational force (as if unscrewing a nut from a
bolt) so as to break the piston-cylinder seizure. This MAY distort
the bottom donut spacer, see item #20, Fig. 12 in the Parts Catalog
(if so, and it cannot be straightened, replace it).
If unsuccessful, try adding torch heat to the (lower) cylinder (where
you can get to it). If a little isn't enough, add a little more. Any
expansion is a good thing, although transient. More than is
absolutely needed is too much. Again, this is no place for the
blacksmith approach of heating things to different colors! DO NOT
apply heat to the (upper) piston. Expansion there works against you.
If still unsuccessful, "overhaul" your Belleville strut assemblies.
Most cylinders will benefit from cleaning and honing, and pistons from
cleaning and flushing out with acetone. Degrease, prime, paint and
lubricate parts as appropriate before reassembly. A coating of STP
for the upper and lower mounting bolts (and threads thereon) in the
process of assembly could reduce wear and eliminate all possibility of
seizure here in the future. STP is a rifle, not a shotgun. In many
places it has properties you DON'T WANT "in play".
Remember, I'm NOT a mechanic. but can do such work "under appropriate
supervision" (as can you).
Regards,
William R. Bayne
.____|-(o)-|____.
(Copyright 2010)
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