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From: wool@oracle.UUCP (Chris Wooldridge)
Newsgroups: net.aviation
Subject: Re: T.O. in Cessna 172
Message-ID: <136@oracle.UUCP>
Date: Sat, 2-Nov-85 21:07:33 EST
Article-I.D.: oracle.136
Posted: Sat Nov  2 21:07:33 1985
Date-Received: Tue, 5-Nov-85 06:37:53 EST
References: <769@bgsuvax.UUCP>
Organization: ORACLE Corporation, 2710 Sand Hill Rd., Menlo Park, CA 94025
Lines: 40
Summary: Lycoming engines in Cessna Skyhawks

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?

During climbout in fixed-pitch propeller airplanes, reduction in RPM is quite
normal, for the same reason prop overspeed can occur in descent if you don't
throttle back.

As for the engine, your mechanic is quite right.   Cessna used the "E" series
of the O-320 until about 77 (I think) when they switched to the "H" series ...
which seems to be about the only "bad" engine Lycoming has ever produced.  A
faulty valve and valve train design causes the engine, which has a recommended
TBO of 2,000 hrs, to burn out quite a bit sooner - sometimes as little as a few
hundred hours.   Cessna recognized this and switched back to a "D" series enginea few years later which has been quite reliable.  There are about 8,000 of these
"H" series engines out there, so if you're Skyhawk shopping make sure you 
check the engine carefully.

Since your airplane is a rental, a valve problem in the engine should be 
detectable at the 100hr inspection as low compression on one or more cylinders.
Check the engine logbook for the figures from the last 100 hr.

Happy aviating ...


(heard last Thursday night before starting a bumpy approach ...)

"Boeing Field Information Transylvania, 0500 greenwich weather, measured
ceiling 700' overcast visibility 2 miles rain, fog.  Wind 160 at 10 gusting
15, altimeter 30.12.  Approach is ILS to 13R.  Advise ground or Seattle 
Approach you have information Transylvania ... AHHH OWWWWWWW!!!!"
-- 
Chris Wooldridge
Oracle Corporation
1100 206th Avenue, N.E.
Redmond, Wa.   98053
(206) 868-1985                {ihnp4!muuxl,hplabs}!oracle!wool