R
EVISION
:
-
D
ATE
:
12/29/04
P
AGE
:
6
Copyright
2004 Glasair Aviation, LLC Arlington, Washington All rights reserved
rings with the cylinder wall will occur only when pressures inside the
cylinder are great enough to cause expansion of the piston rings.
Pressures inside the cylinder become great enough only when power
settings above 65% are used. Full power for takeoff and climb is not
harmful to a new or overhauled engine; it is beneficial. (Monitor
engine temperatures closely, however, to ensure that overheating does
not occur.) For cruise, it’s best to use power settings of 70% to 75%
of rated power for the first 50 hours, or until oil consumption
stabilizes, to produce a good engine break-in.
Unfortunately, the initial ground checks of engine operation, as well as
subsequent taxi tests are characterized by relatively low power settings,
which may not allow proper seating of the piston rings, and by reduced
cooling flow, which may cause overheating and cylinder wall glazing.
Piston rings that fail to seat and cylinder wall glazing can result in
elevated cylinder head temperatures and excessive oil consumption.
One solution to this dilemma is to have an overhaul shop break in your
engine on a test stand before installing it in your Sportsman. This has
the additional advantage of assuring you that the engine is sound
before attempting flight. The ground tests described above will then
verify that the engine functions properly as installed in the airframe.
CAUTION
Operate new or overhauled engines on straight mineral oil for a
minimum of 50 hours or until oil consumption has stabilized.
After this period, change to an approved additive oil if so
desired.