The Engine Saver is designed to supply a
continuous flow of dry air into the
crankcase of an aircraft engine, lowering the moisture level in
the engine, preventing the formation of moisture and rust. A
series of tests were done to demonstrate that the system did
lower the humidity level inside the engine crankcase and in the
upper cylinder area.
Tests were performed on a Lycoming IO-360
engine. Tests were performed in the early afternoon in
September. The aircraft had been sitting for over 24hrs in a
hangar. An Extech model 45320 humidity / temperature instrument
was used to obtain data. This instrument measured relative
humidity in %, and temperature in degrees F. These measured
values were then converted to dew point temperatures as this
form is easier to understand. An initial reading was taken to
determine the temperature and humidity levels in the area around
the engine. A relative humidity (RH) of 38% was measured. This
corresponds to a dew point of 60 degrees F. The dew point
temperature is an important number. It is the temperature that
the air must be cooled to, to cause moisture to form. In this
initial reading, it was determined that air conditions were such
that if the temperature of the outside air were cooled below 60
degrees F, water condensation would occur, and moisture would
begin to form on surfaces. The oil stick was then removed, and
the instrument inserted into the fill tube. Tape was used to
prevent the entrance of outside air. A dew point temperature of
59 degrees F was measured in the engine crank case. A cardboard
spacer with a small central hole was taped to the exhaust pipe to
prevent the entrance of outside air into the exhaust pipe. The
meter probe was inserted into the opening in the exhaust pipe,
and the dew point was found to be 60 degrees F.
The Engine Saver adapter and air tube was
then inserted into the end of the engine breather tube where it
extends from the bottom of the cowl. The tube was inserted
sufficiently so that the foam washers were located above the ice
hole in the breather, sealing it off from the outside air. The
Engine Saver was then plugged in and allowed to run for 30
minutes. At the end of this time, the Engine Saver was turned
off. The oil dipstick was again removed and the meter probe
inserted into the oil fill tube and taped off. The meter
indicated that after 30 minutes. of operation, the Engine Saver
had dropped the humidity level in the crank case from a RH of
38% to 12%. This 12% RH corresponds to a dew point temperature
of 28 degrees F. Initially, the moisture level inside the engine
crank case was such that if the outside air temperature dropped
below 60 degrees F condensation would occur. It is quite
possible that this could occur during the month of September.
After running the Engine Saver for only 30 minutes, the dew
point had dropped to 28 degrees F. There was little chance that
air temperatures could ever drop it this level. The possibility
that condensation would occur in the engine was significantly
reduced.
The next test was to measure the moisture
level of the air in the exhaust pipe after the 30 minutes of
Engine Saver operation. A measured reduction in moisture level
of the air in the exhaust would prove that the dry air was
migrating past the piston rings and into the upper cylinder area
protecting this portion of the engine as well. The instrument
probe was then inserted into the hole in the cardboard cover
taped on the exhaust pipe, and the humidity level was measured.
The moisture level was measured at 29% RH. This corresponds to a
dew point of 48 degrees F indicating that the dry air was
migrating past the piston rings and into the upper cylinder
areas. Although the dew point was not as low as that measured in
the crank case, it was still a significant reduction for only 30
minutes of operation. The air temperature would have to drop to
48 degrees F before condensation would occur.
An
additional test was performed, only this time the Engine Saver
was allowed to operate continuously for 24 hrs before the
measurements were made. Measurements made in the oil fill tube
gave a RH reading of 10%. This is below the minimum reading on the
meter scale. The actual RH reading was probably somewhat less
than 10%, but was beyond the meters capability. The probe was
then inserted into the exhaust pipe and a RH measurement
was made. The instrument read 10% at this point also. Since
these measurements were below the low range capability of the
meter, accurate dew point measurements could not be determined.
However it is safe to say that the moisture level in the engine
crank case and in the upper cylinder area was substantially
reduced by the use of the Engine Saver, and the likelihood of
moisture forming on the precision engine parts was substantially
less than it would have been if nothing was done.
This testing verified that the Engine Saver
functions as described. It reduced the moisture level in the
engine crank case and in the upper cylinder areas. Lower
moisture means less chance of condensation occurring and less
chance of moisture forming and RUST developing. Different dew
point temperatures would have been found if the tests were
performed under different atmospheric conditions. The important
thing is to look at the dew point temperature differences that
were achieved by using the Engine Saver. The fact that the
Engine Saver was able to achieve reductions in dew point
temperatures can be translated directly into an extra margin
against rust formation, and a greater chance of achieving TBO.