From: randy@khan.gatech.edu (Randal T. Abler)
Newsgroups: rec.aviation
Subject: A tale of IFR range, part #3.  Gear failure & a cracked cylinder
Summary: what the prepurchase inspection uncovered
Date: 30 Jul 92 16:02:15 GMT
Originator: randy@khan


In two previous articles, I discussed the factors that led up to club
deciding to sell one of our C172s in order to buy a complex plane.  We
then settled on the Cessna Cutlass RG as a desirable model, and then
we found an attractive looking plane ... 
When we left off I was finalizing plans to fly out to Texas to inspect
the plane.


In planning to go out to Texas, I talked to the CFI that is working
with me on my instructors rating.  He was interested (as a club member
and former president of the club) in checking out this plane, and by
dragging him along I could get him to check me out in flying it from
the right seat, since I have been working on switching seats as part
of the CFI training.  Since his schedule was not completely consistent
with my plans I left him some phone numbers and an itinerary so he
could catch up.

I got out to the FBO and picked up the keys to the airplane Sunday
morning, after borrowing my friends car (with a slipping clutch) and
driving into town from about 100 miles away.  After a very thorough
pre-flight with some screws replaced, and notes of a worn outboard
aileron hinge, I jumped in the plane and fired it up.  I had layed out
a comprehensive plan for my flight test, but had hoped that the CFI
from our club would be there to help since I wanted to check out the
avionics and a second set of eyes would really be needed to watch for
traffic and/or fly while playing with the RNAV, autopilot, and
stormscope.

After documenting the run-up,
my flight plan called for a takeoff and climb direct to 8500MSL (from
about 500MSL) to document climb performance and engine cooling (it
was in the high 90 degrees in Texas on Sunday).  Once at 8500 MSL, I
did some holding patterns to get DME on groundspeed in opposite
directions.  I then did some slow flight, power on and power off
stalls with different gear & flap combinations, and then some steep
turns.  The AI was sluggish beyond what I considered acceptable for
IFR.  The com, nav & dme radios were being used for calling the tower
& navigation, so I knew they worked.  I wanted to shoot an ILS
(under VFR) to verify that markers beacons, glideslope, and ADF were at
least functional.  After calling up approach (and getting a descent to
4000 from 8500 MSL) I decide that lowering the gear would be
appropriate to help loose some altitude since I wasn't that far out
from the airport.  When I looked down at the gear lever, the first
thing I noticed was that the yellow "gear up" light wasn't lit.
Pushing it (lamp test) resulted in nothing, neither did lamp test on
the green "gear down" light work.  Hmm, the "ldg gear" circuit breaker
was popped.  I tried to reset the breaker put it popped back out.  Ok,
this is why they put a manual gear extension mechanism in these
planes.  Select gear down, extend handle, and pump until you get a
green light (which wouldn't happen with the breaker popped).  When the
pumping had the gear fully down (including the nose gear, verified
with a wing mounted mirror), I pushed the breaker in again to see if
I would get a green light, sure enough, I did.  So I followed the path
of least resistance back to ground, by being vectored to the ILS and
landing, not really paying a whole lot of attention to the ILS.  I
didn't declare an emergency, although it wouldn't have hurt.  I had
visual and electronic verification that the gear was down and locked,
so I wasn't worried about having the gear fold up.  When I got back on
the ground, their mechanic was waiting for me, expecting to do a
compression check, cut open the oil filter, open inspection panels,
and provide maintenance logs.

I told him that the gear breaker had blown, and that it needed to be
fixed, then left him to look at it while I went to think about it
(including thinking about dropping the whole deal right there) and
make a few phone calls, including calling our mechanic back in
Atlanta to get some suggestions as to what to double check.  When I
got back to the maintenance hangar, the plane was up on jacks, and
the gear would extend normally via the electric motor, but on
retraction, it would quit about half way up.

As a short lesson in Cessna 172RG landing gear, the hydraulic pump
runs off of a relay which is energized by a series connection of two
switches.  One switch is a pressure switch which runs the motor
whenever the pressure in the system drops below 1000PSI, the other is
the a squat switch which only allows the gear to operate when the nose
strut is fully extended.  The up/down lever directs which way the
pressure pushes, but the system is (should be) always pressurized
to at least 1000PSI when the master is on.  The yellow/green up down
lights are conected to a bunch of switches but have nothing to do with
the actual control the gear motor.

The first suspect was the pressure switch, which we hooked up in
conjunction with a  pressure gauge, and sure enough, on retract, the
gear quit moving before the 1500 PSI  limit, but on gear extension, it
would cut out before reaching 500 PSI.  I convinced the mechanic to
bypass the squat switch, and sure enough, the gear went up and down
repeatedly without a catch.  Since it was a sunday, it would be monday
before a squat switch could be found. Oh well, a new AI could be put
in on monday also.  I drove back to my friends house feeling confident
that the gear problem had been identified and could be completely
corrected by replacing the squat switch.

Come monday morning, I called to check on parts delays, and they had
determined that the fastest way to get the AI was for me to pick one
up were I was staying and bring it up to them.  (They paid for the AI
on account).  When I got to the FBO on monday afternoon, I found out
that the squat switch wouldn't be in until tuesday morning.  ARGH.
Well, since I was there, I wanted to go ahead and do the inspecting of
the airplane (oil filter, compression, etc).  The engine had run
strong the previous day,  and I didn't expect to find anything wrong,
since the plane had just been annualled the previous week.   Since the
plane was still up on jacks (which is pretty high on the drop-swinging
Cessnas), I just ran the compression check with the engine cold,
figuring we could always run it up later if any doubtfull compression
values showed up.

The first three cylinders all showed up in the high 70's for compress
values, but the last cylinder was at 68PSI, with a loud hissing noise.
Took only a few minutes to find that the head was cracked.  Shit.
Damn.  What is going on here?

I wanted to think about this, so I commandiered the courtesy car and
headed into to a hotel room, wondering if I shouldn't check to see if
it was too late to catch a flight home.  Instead I caught a few beers
and dinner at the hotel resturaunt/bar, after making some phone calls
to let the people back in Atlanta know what was going on and to get
their comments, and to tell the CFI not to get on a flight out to
Texas the next morning.

The plane was in nice shape, clean, and well cared for.  The
avionics stack was really nice, but as you can imagine my interest was
waining, if for no other reason than that I needed to get back to
work.  I do not think they new about the cracked cylinder, hell, the
mechanic had just signed it off for an annual, and unless they like
high liability (picture an FAA/NTSB accident investigator looking at
an engine failure on a plane just sold after an annual.  Picture
same investigator talking to shop owner, mechanic, etc).  His reaction
was genuine suprise and worry at finding the cylinder cracked.  Did the
cylinder crack while I was flying it?

I may not be as cautious as some plane owners who reduce power
based on rules like no more than 2" per minute, but I did not
mis-manage the cowl flaps or change power settings by more than about
25% at a time.   I also pondered whether or not a cracked cylinder
could "seal up" when hot, since the compression check done at annual
was done after running the engine. I decided to go out to the FBO the
next morning and see what they proposed to do, after all, the
commercial flights out of town left from the next building, about 100
yards from the FBO.

The FBO owner was in the middle of working with the mechanic to find a
new cylinder and send somebody out cross country in another of their
airplanes to pick up a cylinder.  Ok, they were making the best
possible effort to get this straightened out, so I made a few more
phone calls to club officers back in Atlanta, and decided to stick
with this deal.  Two mechanics put in a rather long day, and with
plenty of interference from me, managed got the new cylinder on.  I
spent a good part of the day going over the airframe with a fine tooth
comb (or Black & Decker cordless screwdriver and flashlight) looking
for anything else to finish off this whole thing.  We test ran the
cylinder several time on the ground, then I took it out for a test
flight.  I test flown two new engines, but am always in extra-alert
mode when doing this.
Me: "Ground, N9754B taxi for VFR in the immediate area with Delta".
Gnd: "54B, do you want pattern work, or out to the practice area"
Me: "54B, new cylinder just put on the engine, I want to stay within
easy gliding distance"   (You don't do pattern work on a new cylinder)
Gnd: "54B, we understand, can you stay just E of runway 19?"
 ... Just let those guys in the tower know whats up instead of making
them guess and most of them will do their best for you.  Review the
runway layout for the "impossible turn" decision points, and I took
it up for about an hour of test flying before it started getting too
close to sunset to be flying a new cylinder.  Back on the ground,
and de-cowl for another check.  Everything looks OK.  Hey, you mean
this thing is actually airworthy again!?!  Back to the hotel, feeling
more numb than anything else.  My CFI had caught up with me at the
hotel and was anxious to see the plane, but I was ready for a shower &
a complimentary brew in the hotel bar.

We flew it back from Texas Wednesday morning.  The RNAV needs to be
worked on, it doesn't slave to the VOR on certian frequencies.  The
stormscope never showed a thing, and we deviated around more than one
buildup that was dumping a lot of rain out and generating static on
the radio.   But it flys nice.  And its ours.  Now the teething
begins, maybe some of its appetite is satisfied out of the sellors
pocket ...  time will tell.

-- 
Randal T. Abler   	randy@cerl.gatech.edu		 
CERL/EE Georgia Tech