Hélicoptères Guimbal
LETTRE SERVICE
CABRI G2
SL 13-001 A
Original issue
3 / 4
Limitations concerning flight operation :
4. Fuel volatility
Automotive gasoline volatility is higher than that of AVGAS. This can lead to
power losses due to vaporization in the circuit if altitude and fuel temperature
limitations are exceeded.
There are several volatility classes for automotive fuels, but this information is
generally not explicitly indicated on gasoline outlets.
The Flight Manual therefore gives a safe Altitude-vs-Fuel-temperature limitation
to be used when operator has no access to detailed gasoline characteristics.
If the operator has access to certificates of analysis, less restrictive limitations
are given as a function of RVP (Reid vapor pressure).
It should be known that oil companies usually supply less volatile fuel during
summer, generally from May to October in Northern hemisphere; Practices and
rules vary from one country to another.
In general, “summer” grade corresponds to an RVP pressure of 60 kPa. This
characteristic allows to use gasoline in the same conditions as AVGAS.
“Winter” grade generally corresponds to an RVP pressure of 90 kPa, slightly
less than the lower limit of the standard. That is why a corresponding
intermediate curve is also given in the Flight Manual.
Caution :
It is not guaranteed that gasoline sold under a given name has
always the same characteristics and the same origin from one delivery to the
next. The operator therefore has to ensure that they are compliant for each
delivery.
Additional limitations and constraints regarding procurement, storage
and handling of gasoline (not regarding the Flight Manual).
Attention of the operator is drawn to the fact that storage and handling of
gasoline is subjected to complex national regulation independent of aviation
use, particularly :
•
Regulation on transport safety,
•
Regulation on health,
•
Regulation on environment protection,
•
Regulation on labor,
•
Tax regulation.
It is operator's responsibility to comply with these regulations.