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From: cfiaime@ihnp3.UUCP (J. Williams)
Newsgroups: net.aviation
Subject: Re: T.O. in Cessna 172
Message-ID: <176@ihnp3.UUCP>
Date: Thu, 31-Oct-85 09:33:00 EST
Article-I.D.: ihnp3.176
Posted: Thu Oct 31 09:33:00 1985
Date-Received: Sat, 2-Nov-85 04:34:25 EST
References: <769@bgsuvax.UUCP>
Reply-To: cfiaime@ihnp3.UUCP (45261-J. Williams)
Organization: ATT Bell Labs
Lines: 37

In article <769@bgsuvax.UUCP> dewitte@bgsuvax.UUCP (Anne Dewitte) writes:
>In the 172 that I rent I noticed my take-off r.p.m. was only 2200 which is
>just the beginning of the green arc.  I had 3 others in the plane and was
>getting a bit nervous.  I learned from the mechanic that the engine is a
>0-320-H2AD and it is a piece of (junk).  I'd like to know what other's
>take-off r.p.m.s.  Is it this particular engine or characteristic of all
>0-320-H2ADs?

If you watch the RPM on any fixed pitch prop airplane, you will notice
that takeoff and climb rpm is somewhat less than red line.  It seems 
that with the pitch of the prop on a 172, it is particularly noticable.
BUT, 2200 rpm is a bit low.  At that point, if concerned about the 
engine, I would have aborted the takeoff and had the mechanic look the
engine over.  When in doubt, DON'T FLY.

As for the O-320-H2AD itself, this is not one of Lycoming's better 
contributions to aviation.  Early ones had valve lifter problems, oil
pump problems, and (I think) cam shaft problems.  This lovely little
engine :-) was so reliable that in 1978 all of the engines were grounded
pending inspection.  We had one that had under 3 hours from the factory
and needed replacement.  (I was working for a ferry service in Wichita
at the time.)

Another problem with later Lycoming designs in general is the wonderful
invention of the "twin pack" magneto.  Let's face it, gang, a mag typically
dies because of a mechanical failure in the drive, not an electrical 
failure within the mag itself.  Sure, Eiseman mags blow condensors,
and old Case mags may have swollen rotors, and there is an AD on the
coil in old Bendix mags, but MOST OF THE TIME the failures are in the
nature of a broken drive.  So what does Lycoming do?  Sure, a common drive
for both rotors.  You lose the drive, you lose all spark in your life,
so to speak.  Don't you love what companies do to save a few dollars in
production costs?

					jeff williams
					ihnp3!cfiaime
					AT&T Bell Laboratories