Message-Id: <200106072126.f57LQIf85896@king1.vineyard.net>
From: "Ted Stanley" <direct@vineyard.net>
To: "LML reply address" <lancair.list@olsusa.com>
Subject: re: TCM service, gyro's, etc.
Date: Thu, 7 Jun 2001 17:23:22 -0400
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Reply-To: lancair.list@olsusa.com

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Jim -

Your comments are interesting, however Chip McClellan's information does
not precisely agree with that found in the overhaul manual.

The overhaul manual on page 18-30 says:

See Figure 9-1D. Apply TCM gasket maker to silk thread and split line
of crankcase at fuel pump bore. Place silk thread ends into split line of
fuel pump bore.

Apply molyshield grease to fuel pump drive coupling (2). Install fuel
pump drive coupling (2) in fuel pump (3). Install new gasket (2A) on fuel
pump. Lubricate fuel pump cavity with clean 50 weight aviation engine oil.
Install fuel pump on crankcase studs. Secure fuel pump using attaching
hardware (4,5, &6). Torque nuts (6) to 180-220 inch pounds.

I can tell you that I recently installed two factory rebuilt IO-550-C
engines on my Baron and had to remove one fuel pump to make a slight change
in its position relative to other components. I found the same material you
describe as appearing to be "congealed preservation oil". TCM Gasket Maker
in an uncured condition has the appearance of a viscous, purple colored,
sticky material. My guess, based on my own observation of a fuel pump on a
recently rebuilt TCM IO-550, and the above information from the overhaul
manual, is that Gasket Maker is indeed used in this application.

Gasket Maker is an anaerobic compound which means that it cures in the
absence of oxygen. This is advantageous during engine assembly where excess
quantities of normal sealants can find their way into places they don't
belong.

This dichotomy of information is why I often find myself checking, and then
cross-checking data. I've found several cases where data from two
authoritative sources fails to agree. I've also found single sources of
information from manufacturers that is simply incorrect for various
reasons. A good example of this is torque values. Occasionally you will
find, with respect to TCM, that their manuals have torque values that
differ from those found in the latest edition of SB96-7 - Torque Limits. A
TCM rep advised me to use the torque values found in the service bulletin.
His reasoning was that the bulletin was typically more current than the
manual. Happily this is the exception rather than the rule.

Bottom line is you want a fuel pump that is securely mounted and doesn't
leak oil.

With respect to TCM's slow response regarding the incorrect fuel pump
fittings, I can sympathize and agree. It should not have taken so long to
resolve your problem. Perhaps it's cultural, sometimes things just don't
move very fast in the deep south.

I can recall many years ago hearing a turboprop pilot call for his
clearance from a Boston area airport to some distant destination. The young
female controller rattled off the long and complicated clearance at the
speed of a tobacco auctioneer. When she finished the pilot came back and
said, "M'am, we're from the south and we don't talk quite that fast... could
you read that clearance again a little slower?"

Ted Stanley


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