From: bunda@cs.utexas.edu (John Bunda)
Newsgroups: rec.aviation
Subject: Engine swaps, dash-numbers, and the Feds
Date: 19 Aug 1992 11:43:13 -0500
Organization: CS Dept, University of Texas at Austin
NNTP-Posting-Host: peaches.cs.utexas.edu

A friend of mine faces the following problem (I'm glad it's not me).
I'd be interested to hear if anyone has suggestions, knowledge
of a possible solution we're overlooking, or anything else to 
offer.

The aircraft is a 1958 Skylane, which came originally with an O-470-L
engine.  Over the years, Cessna went through the series of O-470s in
the 182.  Early on (60's sometime) they switched to the O-470-R.  At
one point, they went to the O-470-S, which lasted a single year before
fouling problems with 100LL (or some such) prompted the final
switch to the O-470-U.  The main differences in these engines, range
from crankshaft counterweights, slightly different crankcase
dimensions and total weight, high-compression pistons in the -U, etc.,
but by and large they are reasonably interchangeable, and
considered such on most of the later Cessna models.

My friend's 1958 182 has an O-470-S, with, you guessed it, no trace of
this installation having ever been approved.  It had this engine when
he bought it years ago.  My friend learned about the problem at some
point along the way, but on the sleepy little airport where he kept it
nobody paid any attention.  It had been into most of the shops and
repair stations in the area, and logbooks were signed by a lot of
people who, depending on where you stand on this, were understanding
folks who turned a blind eye, or "should have known better".  Well,
the old A&P on the field retired, and a new guy shows up.  He notices
right away that the engine is "wrong", and of course, refuses to sign
off any work on it (for which you can hardly blame him).

My friend says, okay, time to deal with this.  He calls up the
Friendly Aviation Advisors (FSDO), and anonymously, relates his story
and asks their advice.  The advice was, get your paperwork
together, call us back, and we can probably issue you a one-time field
approval.  He was left with the impression that they weren't happy
about it, but the problem wasn't that big a deal, and provided the
paperwork was in order, all would be fine (after all, the plane
has been "test-flown" for years).

You can probably see what's coming.  The inspectors come out to
look things over, and deny the approval.  While they claim they 
really don't have any problem with the installation, the paperwork,
or anything technical, what they _are_ upset about is ten years
of signoffs by virtually everybody in the area.  Supposedly,
there was talk of pulling the tickets of everyone who ever
worked on the plane, but realizing that would probably shut down
general aviation within a 100 mile radius, they eventually backed
off, and decided to just pack up and leave.  My friend's plane wasn't 
grounded, but he didn't get his approval either. 

It could be worse, the engine is basically at TBO, and solving
the problem won't be as expensive as it would be if this had
come to a head earlier in the engine's life.  I saw a similar
situation last year with an Apache conversion that had wrong
dash-number Franklin engines (and the difference had no bearing
on airworthiness).

The worst part is the (typical) FAA reaction.  Rather than trying 
to work with the owner to solve any (real or imagined) technical 
problems, there is this preoccupation with punitive enforcement
action.  Now I have no problem with them sending out tsk, tsk
letters, or whatever is appropriate, but denial of the approval
should be based on technical, not political grounds (yeah, ha ha).
	
In this case, going for full STC approval is overkill - the engines
are already considered interchangeable on later models, but the newer
engine didn't exist when type certificate for the earlier planes was
issued.  Plus, the applicability would be too narrow to justify the
process.  Caveat emptor.


-- 
John Bunda * bunda@cs.utexas.edu * {uunet,harvard}!cs.utexas.edu!bunda

Newsgroups: rec.aviation