Safety First The Airbus Safety Magazine Edition February 2010(6)

ramp fuel index table  is calculated with the following formula:

The Ramp Fuel Index replaces the Takeoff Fuel Index of the original simplified calculation because, on all Airbus aircraft, the taxi fuel is burnt in the tanks located near the aircraft’s CG position.
Figure 3

On Airbus aircraft the taxi fuel is
consumed from:
qThe inner/wing tanks on the
A300/A310/A318/A319/A320/
A321/A330/A340.
qThe feed tanks on the A380.

As a consequence, the taxi fuel index
can be considered to be negligible.

On the A330 used to illustrate our
article, the calculation of the TOCG
by means of the improved simplified
calculation would have given aTOCG
at 26,3% MAC, corresponding to
a pitch trim setting of 4.3 degrees
NOSE UP. This is very close to the
TOCG at 26,7% MAC and the pitch
trim setting of 4.1 degree NOSE UP
that would have resulted from calcu-lation using the complete calculation.

With the improved simplified
TOCG calculation, the difference
between the calculated TOCG and
the real TOCG decreases from

The Airbus Safety Magazine

Figure 5
Electrical discharge from cell phone

Figure 6
Open the valves slowly

There are numerous potential sources of ignition, herewith a non-exhaustive list:
qRaw flames, from cigarettes for example. It is important to keep in mind that clothes and hair tend to absorb oxygen, consequently people exposed to an oxygen en-riched atmosphere should refrain from smoking for at least 15 min-utes after leaving the O2 enriched area (fig.3 & 4).
qIncandescent particles, from grind-ing or drilling for example. It is im-portant to stop all operations that cause heat and flames. As a general rule, avoid all maintenance activities less than 5m (15ft) away.
qElectrical overheating (from elec-trical engines, poor contact…).
qElectrical discharge from static electricity or from a short circuit for example.
Remember to ground the aircraft and oxygen servicing equipment and to bond them together. Put a warning notice in the cockpit, the work area and the cabin to warn not to operate electrical switches dur-ing the oxygen filling procedure.
Do not use mobile phones. If there is a risk of lightning during thun-derstorms, stop all oxygen servic-ing operations (fig.5).
Other non –obvious sources of ig-nition may be oxygen overheating due to:
qToo rapid pressure build-up when servicing the system. Ensure that the pressure in each oxygen cylinder increases smoothly.
qToo rapid opening or closure of oxygen valves can result in high oxy-gen velocities causing frictional heat. Open the hand-valves of the oxygen cylinders very slowly, and turn them to the fully open position (fig.6).
(if hand-valves are not fully opened before flight, the oxygen pressure readings on the ECAM page may be incorrect).
　
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