Hi Rowland and all,
In my opinion, EGT indication on any Rotax engine is useless. EGT
indication is extremely sensitive to the position of the probe inside
the exhaust stack. This is one of the reasons why, on any piston engine,
the EGT indication in itself cannot be used to determine whether a
cylinder is running too lean or too rich. The highest EGT cylinder is
not necessarily the leanest. The only way to determine the mixture
condition is to pull the mixture control progressively and monitor the
EGT on all cylinders. The leanest cylinder is the one which will reach
peak EGT first. Of course you cannot do that on a Rotax as there is no
mixture control. The only thing EGT can do on a Rotax, in case of a big
engine problem, is to help diagnose which cylinder is the culprit.
Additional comments:
With the Europa XS cowling, the EGT probes on cylinders 1 and 2 are
cooled by direct ram air from the round intakes and this has proved to
affect their indication.
The Rotax Flydat has 4 EGT channels but shows EGT on two cylinders at a
time and switches automatically back and forth. That makes EGT very
uneasy to read. Any other engine monitor on the market is certainly
better.
My plane was fitted with a 914 with Flydat and 4 EGTs when I bought it.
When I replaced the engine with the 912S five years ago, I kept the
Flydat but did not install EGT probes and it works for me.
Regards
Remi Guerner
F-PGKL
<<<<<< as there's no mixture control, EGT
indication does not add much to the CHT/coolant indication that comes
as standard. >>>>>>>>
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