Fuel Limitations

The fuel limitations cover two things you check and one thing you choose: the fuel-pressure limits shown on the gauge, and which fuels are approved for the engine. This lesson lists both, together with the caution that applies to running the aircraft on AVGAS.

At a glance

• Fuel pressure, minimum2.2 psi (0.15 Bar)
• Fuel pressure, maximum5.8 psi (0.40 Bar); or 7.26 psi (0.5 Bar) with fuel pump p/n 893110, 893114 or 893115
• Usable fuel (placard, per tank)97 litres (25.6 US gal)

Fuel pressure

Minimum fuel pressure is 2.2 psi (0.15 Bar). Maximum fuel pressure is 5.8 psi (0.40 Bar), or 7.26 psi (0.5 Bar) where fuel pump part number 893110, 893114 or 893115 is fitted.

Approved fuels

Three fuel specifications are approved:

• MOGAS ASTM D4814

• MOGAS EN 228 Super / Super plus (minimum RON 95)

• AVGAS 100LL (ASTM D910)

The same approved fuels are printed on the fuel-type placard at each filler cap, which also gives a usable capacity of 97 litres (25.6 US gal) per tank.

CAUTION — Prolonged use of AVGAS 100LL causes greater wear of the valve seats and greater combustion deposits inside the cylinders, because of its higher lead content; avoid it unless strictly necessary. For prolonged use, the Rotax Maintenance Manual prescribes dedicated checks.

Check yourself

• What are the minimum and maximum fuel-pressure limits?

• Which fuel specifications are approved for this aircraft?

• Why should prolonged use of AVGAS 100LL be avoided, and what does the manual require when it is used?

• What usable fuel capacity per tank is given on the filler-cap placard?

Study aid — always fly your aircraft's current AFM/POH.