EU-OPS 1.255 Final Reserv Fuel

[JMJ828]

Hi,

EU-OPS Subpart D Appendix 1 to 1.255 states that:

1.5. Final reserve fuel, which shall be:
(a) for aeroplanes with reciprocating engines, fuel to fly for 45 minutes; or

(b) for aeroplanes with turbine engines, fuel to fly for 30 minutes at holding speed at 1 500 ft (450 m) above aerodrome
elevation in standard conditions, calculated with the estimated mass on arrival at the destination alternate
aerodrome or the destination aerodrome, when no destination alternate aerodrome is required.

The Final Reserve Fuel for a turbine engine is there no questions about. It's clear. But when it talks about Final Reserve Fuel for reciprocating engines is not as clear under what conditions we calculate these 45 min, anyone knows?

In the books we use for class (Oxford 4th Edition) pg. 44 states "It consists of 30 min (jet/turbo-prop) or 45 min (piston) fuel consumption at endurance speed.
Pg. 45 states "Final Reserve Fuel Is simple calculations based on 30 (jet/turbo-prop) min or 45(piston) min hold at endurance speed.

Anyone that has a good explaination of this?

Thanks

[Oktas8]

If I've understood your question, does this provide the explanation you had in mind?

You're a commercial pilot who wants to carry as little fuel as safety & the law permits. The law allows you to calculate the 45 minutes at any power setting and any altitude (although close to an airfield is a practical interpretation).

So you carry 45 minutes' worth of fuel at minimum fuel burn, or endurance speed. Why carry fuel for 45 minutes at cruise power when safety & the law doesn't require it? The light twin I fly burns about 12 USG/hr at cruise power, but about 5.5 USG/hr at endurance power.

The "hold" just implies that you don't have to set cruise power - set whatever power (therefore fuel consumption) you require to hold in the vicinity of an airfield - presumably while they clear the runway, or do whatever is necessary to allow you to land.

Reciprocating engine aircraft fuel consumption doesn't change much with altitude or weight, so they don't bother to specify 1500'AAL or Landing Weight as they must for a turbine powered aircraft.

Regards,
O8