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> This is interesting. For example, I have questioned the reason why the
> PA38 has such a useless elevator trim - it is a crude spring pushing
> against the elevator control, and is little better than useless. I was
> told that no mods can be done to an a/c - all you can do is replace
> something with the same design.
Dont know what country youre writing from, but most countries have rules
that distinguish between "minor" and "major" modifications. Check with your
local licensed mechanic or government office to get the details in your
In general, minor mods are mods that do not affect primary flight controls,
structures, crew access/ingress, or essential systems. These can usually be
done by a licensed mechanic or shop, as long as the work is performed within
certain guidelines. See my old buddy AC43-13, for instance. Avionics are not
my specialty, but I suspect the extra jack for a hand held mentioned by an
earlier post would be a minor mod, if done properly.
Major mods are subject to the same approval process as the original aircraft
went through. This means (in general) submitting test and analysis results
to a government office or an airworthiness engineer delegated by your
government, followed perhaps by testing. This might mean getting an
experimental flight permit for the modified aircraft. You have to love
An elevator trim system is very much a major mod. Dont mess with this,
unless you have some knowledge in the area, or a death wish.
Now, it helps to be an experienced manufacturer or modification business
when you apply for a major modification approval, but in theory anybody can
do it (God, the government guys are going to hate me when they read that).
Check the home pages of your local FAA, TC, CAA or whatever. Be prepared to
fill out everything in triplicate :).
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