Book Review:Maintenance/overhaul guide to Lycoming aircraft engines, Christy

From: Gene Kearns
Date: Wed, 22 Dec 2004 10:07:18 -0500
Local: Wed, Dec 22 2004 7:07=A0am
Subject: Book Review:Maintenance/overhaul guide to
This is typical "engineer" mentality.

If a product can be made more complex, or if it can be squeezed for
one more 1/2% of power, or if it could be installed in a smaller space
or made smaller somehow, or if it could run off of some boutique fuel,
it would absolutely obsolete everything coming before, regardless of
the original product's history.

There are enough engineering failures to underscore this mind set.
I'll give you two..... Continental's Tiara engine and Lycoming's
experience with the GSIO-720-A1A.

Some of these engines may not be that far from a 1937 tractor engine,
but, you know what? 65+ years later, we still haven't found anything
affordable and reliable enough to replace them.... AND if they were
sold for what they were *worth* they probably sell for less than $1000
per cylinder, new..... but that is another story....

The Continental Tiara was an example of ignoring the published
literature. Any gear designer could tell them that 2:1 is the worst
ratio because the same teeth see each other every other rev. It's in
all the books. They tried to use the cam gear as a reduction gear, a
stupid idea.

I have no experience with geared 720s but I remember well the TIGO-541
and the GSIO-480, both of which were marvels of trouble. The 480 had
an oddball mechanical injection system used nowhere else.

If Lycoming or Continental had to make their ridiculous contraptions
work in anything except an airplane, they would probably quit and go
home. No one ever mentions that the reason the O-290-G engines were
available cheaply until modern times is that they were an absolute pain
in the ass in their original homes. Continental was smarter than to
try to sell the IOL-550 as a sport boating engine, even though many
custom Chevys sold for as much as the Continental did in aircraft trim.
Twenty years of ski and fishing boat experience have convinced me that
given a professionally engineered reduction drive a Chevy or Ford V8 is
a lot more reliable than any engine with bolt on cylinders and a split
crankcase.