Page 740 - PPL-engelsk 2025
P. 740
Aircraft general knowledge
This is done by closing the adjustable air damper. Air resistance is reduced when
the cowl flaps are closed.
Cowl flaps open: Cowl flaps closed:
- Taxi - Cruise
- Take off - Descent
- Climb
Back to table of contents
8.9.5 Air-gasoline mixture
Do you know difference in price between gasoline and air? An 8% lean mixture
is called the “economically best mixture”. Here, we are only thinking about fuel
economy. If you lean too much you can burn exhaust valves, and they are
expensive!
It can also be the economically best mixture for the mechanic!
Remember that every time you change altitude or make changes to the throttle,
the mixture must be readjusted.
8.9.5.1 Leaning
If you are flying in an aircraft without instruments for measuring exhaust gas
temperature (EGT Exhaust Gas Temperature), the mixture is leaned by slowly
pulling back the mixture lever when you are established at the altitude you want
to fly at.
When the engine starts to run poorly, push the lever forward until the engine
runs smoothly again.
To ensure that the engine lasts the prescribed run time, the lever is pushed
forward a little further. That is, we are flying on the rich side of peak
temperature.
Flyveteori PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 740
