Section 7 - Diagnosing Engine Problems
Normal Engine Limits
The follow chart lists typical
normal
measurement values that you
will observe for most general aircraft engines.
Measurement
Normal range
Comments
EGTs in Cruise
1350°F
1550°F
under 200 HP
high performance
EGT should drop
200°F when full
throttle is applied
EGT span (DIF)
70 to 90°F
120 to 150°F
fuel injected
carbureted
TIT
1600°F average
100° higher than
EGT
CHTs
350°F(OAT 60°F)
410°F
normally aspirated
Turbocharged
CHT span
50 to 70°F
OIL
200°F
oil cooler thermostat
opens at 180°F
Shock cooling*
-40°/minute
-55°/minute
-200°/minute
tightly cowled
Bonanza
helicopter
* Maintain a cooling rate of less than -60°/minute. You will find that the
cylinder with the greatest shock cooling will shift from front cylinders
(during climb out) to the rear cylinders (during descent ).
If one CHT is reading 20° to 50° above or below the others, this may be
due to that cylinder having a spark plug gasket probe instead of a bayonet
probe. This is necessary because the aircraft’s factory original CHT probe
is occupying the socket in the cylinder head rather than the EDM-
760/790. This is normal. If the discrepancy is greater, be sure the spark
plug gasket probe is mounted on the
top
spark plug. There is also a
gasket probe that fits under your factory cylinder head probe. Contact
your dealer.
For Your Safe Flight
Page 25
Summary of Contents for EDM-760 TWIN
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