Fuel System and Fuel Measurement - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 66

been replaced with a new electronic regulator, the Full Authority Digital Engine
Control (FADEC) [ 30 ].
The main elements of the FADEC system are the micro electronic system, the
sensors, and the actuators, and several elements for signal processing, such as
the analog-digital transducers, the multiplexers, and the micro processors. In the
airplane redundancy systems two permanently active channels generate signals,
including sensors for monitoring the power supply. Modern electronic and micro
computer systems enhance the reliability of the FADEC system compared with
hydro-mechanical systems.
4.2.3 Fuel Planning
Safety is the most important task in aviation. There must be enough fuel on-board
at departure to cover the planned distance, the ground operation needs, and the
amount has to meet the regulations for mandatory reserves including engine failure
and reaching an alternate airport if necessary after takeoff, climbing, cruising,
descent, and landing.
The basic standards regarding fuel are contained in ICAO Annex 6 to the
Chicago Convention, establishing the acceptable minimum level of safety for
international civil flight operations and are reflected in the national codes. The
national codes, such as the Federal Aviation Regulation for US Federal Aviation
Administration and the European Operation Performance Standard (EU-OPS) for
the European Community, may differ from each other, but must not be less
stringent than the corresponding ICAO standard [ 31 ]. EU-OPS is very common to
JAA-OPS [ 32 ].
Conventionally, the planned route must be in close vicinity of airports so that in
case of an emergency like an engine failure, the airplane must be able to reach an
airport within 60 minutes with one engine inoperative. As a result, instead of
traveling straight, the route may become curved, consequently increasing the trip
distance and the required fuel.
An airline operator has to decide on the amount of fuel on-board with due
regard to IFR for all phases of operation [ 33 ].
Figure 4.7 presents the flight segments of a typical trip at an altitude of 1,500 ft
(457 m) above departure to landing at the destination [ 34 ].
For safety reasons a departing airplane must have a quantity of fuel on-board
not less than the sum of the amount of:
• Taxi out fuel, the fuel required at the departure airport for ground movement,
i.e., from the gate to the takeoff runway end. It diverges from the final reserve
fuel;
• Trip fuel, the fuel required to fly from departure to destination;
• Route reserve fuel, generally 5% of the required trip fuel quantity;