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Included below is a reprint of part of an article from the July 23, issue
of Western Flyer. The article was brought to my attention by Bill Maddox
who thought the question of which version of TCM engines Lancair builders
get to use in their aircraft was significant and related to the info in
this article. If you'd like to read the entire thing it's available at the
Western Flyer website at http://www.flyer-online.com/Articles/flyer.lasso?-database=flyer%5farticles.
fp3&-layout=main&-response=articledetail.html&-recid=33938&-token=searching&
-search
(Sorry for the large URL... but it's the actual address required for the
article.) You can also search it out yourself at the www.flyer-online.com
website by looking for articles in the 7/23/99 issue using the keyword TCM.
A QUESTION OF BALANCE
The utterly smooth idle of the new B58 Baron immediately points up the
biggest improvement in Raytheon’s piston planes:
the Special Edition mills that TCM builds exclusively for the three
Beechcraft.
The folks in Mobile, Alabama, literally started a second assembly line
within its established production line, and that
“factory within a factory” does nothing but build up engines for the Baron
and the two Bonanzas.
Complaints about wear and vibration of TCM engines that power Beech
aircraft has achieved a nearly legendary status
among customers of new planes and new engines. The top squawks: high oil
consumption; low compression; cylinder and
cam corrosion; and excessive vibration — particularly on the Baron.
Over several years, Raytheon accumulated reams of input from pilots and
dealers. Top overhauls between 300 and 600
hours had become far too numerous, too corrosion-related. High oil
consumption and low compression were also among the
leading complaints. Vibration was addressed largely by balancing props. TCM
launched Top Care at the start of 1997 in an
attempt to deal with the wear and corrosion complaints, but even that
wasn’t working as hoped.
And then there was the question of balance, to borrow an old Moody Blues
line. Better cylinder honing and coatings, shorter
shelf times between engine completion and regular use offered nothing to
eliminate complaints about shakes. That’s where
the second line came in.
TCM improved both the IO-550 B and C used on the naturally aspirated
Bonanza and Baron, and the TSIO-520UB used on
the turbocharged Bonanza B36TC. TCM basically adopted engine-building
techniques that are more common at custom
shops — and superior to the standards used on the regular line.
Here’s the quick-and-dirty of the improvements:
* Crankshafts, counterweights and gears balanced to within 12 gram inches
versus 21 for the standard TCM engine.
* Connecting rod set balanced to within two grams versus 14.
* Pistons matched to within two grams versus 14 for opposing pistons only.
* Combustion chambers matched in volume to within 3 cubic centimeters
versus 201 to 209.
* Intake manifold flow rates matched exactly versus no matching for
standard engines,
A lot more has been done to the Special Edition engines that isn’t
incorporated in standard-issue TCM engines.
* Changes to the intake valves to improve breathing.
* A cam change to reduce wear.
* Intake valve springs matched into sets.
* Stainless steel dowels used to hold alignment of the engine-case halves.
* Stainless steel exhaust-port studs.
* Matched fuel-injector nozzles.
* improvements to the oil pump, oil journals, the vernatherm and oil cooler.
Raytheon even styled the engine compartment, with an abundance of shiny
stainless steel nuts and bolts, special rocker
covers, plated hardware and color-matched ignition harnesses and hoses.
Even the inside of the cowling is painted.
Because of the tuning and power tricks that are employed to balance fuel
and air flow, all six cylinders of the big-bore
Continentals run closer in temperature; as a result, the engines can
confidently be leaned more aggressively. With better oil
flow and cooling, more durable hardware and assembly techniques, the
engines stand a better chance of going to TBO. And
thanks to the finer balance component and the three-blade props used across
the line, these engines feel nearly turbine-like at
all power settings.
The smoothness is instantly apparent upon engine start of either Bonanza
single. In the Baron, it’s initially somewhat surreal.
At cruise power with the props synchronized, it’s outright impressive.
TCM feels considerably more confident in its Special Edition engines, as
evidenced by a full-warranty period of two years
or 720 hours. For other new TCM engines, the standard warranty stands at
six months or 240 hours.
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