Important! - See
Hiller engine
12EPN001:
The
yellow arc on the engine tachometer is an avoid area of
operation because a natural resonance frequency occurs which can
cause the engine cooling fan to crack or be damaged.
...................................................
12EPN002:
Fuel usage:
Fuel
consumption rate. Cruise at 21MAP gives about 66 Litres /hr –
mustering at 18 MAP gives about 55-58 (both @ 3100 max).
Remember
that smooth, slower collective inputs means that the
accelerator pumps in both the carburetors do not squirt
so much raw fuel into the engine
and therefore you can have a significantly lower fuel consumption
Hiller 12E Factory Flight Test
Procedures: