From: dst+@cs.cmu.edu (Dave Touretzky)
Newsgroups: rec.aviation
Subject: just lucky, I guess
Date: 25 Jul 92 06:03:11 GMT
Organization: School of Computer Science, Carnegie Mellon


Boy am I a lucky guy!  Last Sunday, a pin on my Seneca's nose wheel
centering mechanism snapped as I was turning the plane around in front of
the hangar.  I didn't realize what the "clunk" sound was; I made a cursory
inspection after shutdown but found nothing out of place and nothing lying
around on the ramp that I could have run over.  The pin was overstressed
because, sometime over the last few months, a line guy exceeded the turn
limits while towing the aircraft.  This bent the housing on the nosewheel
assembly, allowing the wheel to turn past its stop and place excessive load
on the pin.  My mechanic said the corrosion pattern on the pin indicated it
had been nearly severed for some time.

In Piper school they warned us about the turn limit problem, but I'd never
actually seen what a bent housing looks like.  It doesn't have to bend much
at all; just enough to allow load to be placed on the centering pin when you
make a tight turn while towing, or perhaps taxiing.  I hadn't caught the
bending on preflight because (a) the distortion is not all that dramatic
looking to a non-mechanic, and (b) I didn't really understand what to look
for.  Now I do.

Bad news #1:  a replacement housing costs $1200, if you can find one in
usable condition.

Bad news #2: I can't find a replacement pin.  My mechanic told me that there
is an EIGHTEEN MONTH DELAY getting these parts from Piper!!!  Apparently a
lot of people need them, and the junkyards have been cleaned out.

He's talking about getting a machine shop to fabricate a new pin for me, but
it will take several days to get materials data from Piper and engineering
approval from the local GADO.  And I have a trip to Bloomington coming up on
Wednesday, with three other people relying on me for transportation.

Oh yeah, I should explain why I really am such a lucky guy.  You see, I
didn't know that the pin had snapped. The next time went flying, I hope I
would have found the snapped pin during the preflight inspection, but you
never know.  If one is rushed, it's easy to "look but not see".  I've done
it before.

The very next time I flew the plane, the nose gear would have jammed inside
the gear well when I retracted it, and I would had to land without a
nosewheel.  That would have been fatal.  (Sure I could still have landed the
plane okay, trashing the props and the nose but saving at least one engine.
But then I would have gone home and stuck my head in the oven.)  Fortunately
my mechanic was doing some minor work on the plane in preparation for my
upcoming trip, and he noticed the nose gear problem.

This is the third time in 2.5 years that the Seneca has let me down due to a
mechanical problem.  The previous times were due to corrosion inside a prop
hub -- also just before a trip to Bloomington, and the long engine overhaul
saga I wrote about last year which resulted in multiple trip cancellations.
My little fixed gear, fixed pitch Cheetah was a much more reliable aircraft,
even if it was useless for business travel 7 months out of the year (icing
season.)

Fortunately I've been able to reserve a Cherokee Six to take me and my crew
to Bloomington.  But I'm still pissed.  If I had REAL money, I'd buy me a
pressurized Baron.  Beech may charge outrageously for parts, but at least
they HAVE parts.  Grrrr.

-- Dave Touretzky,  CFI-AIM,  Seneca N8147E (``The Bothersome Beast'')
Newsgroups: rec.aviation