Chapter

17

Fuel Jettison

Fuel Jettison					213
Jettison System Certification Requirement . .	. . . . . . . . . . . .	. .	. .		.213
Jettisoning Procedure					213
Safety . . . . . . . . . . . . . . .	. . . . . . . . . . . .	. . .	.	.	213
Questions . . . . . . . . . . . . . .	. . . . . . . . . . . .	. .	. .		.214
Answers . . . . . . . . . . . . . .	. . . . . . . . . . . .	. . .	.	.	216

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17 Fuel Jettison

Jettison Fuel 17

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Fuel Jettison 17

Fuel Jettison

In the event of an emergency occurring when the aeroplane mass exceeds the maximum landing mass, and the decision of the commander to land as soon as possible, a system is fitted to the aeroplane to dump fuel by a controlled process. The system used to facilitate this is the fuel jettison system. Every aeroplane must have a fuel jettison system fitted unless the maximum landing mass exceeds the maximum take-off mass less the mass of the fuel necessary to carry out a 15 minute flight consisting of a take-off, climb to safe height, go-around and landing at the aerodrome of departure (all flown in the landing configuration). The use of a fuel jettison system in an emergency is not prohibited by the Rules of the Air prohibition on the dropping or spraying of materials from aeroplanes.

Jettison System Certification Requirement

Where a fuel jettison system is required, the system must be capable of jettisoning enough fuel in 15 minutes (starting at max take-off mass) to reduce the aeroplane mass to enable the aeroplane to meet the climb requirements of CS-25. Prior to certification, jettison trials must demonstrate that the jettison system is free from fire hazards, fuel discharges are clear of the aeroplane, fuel or fumes do not enter any part of the aeroplane and that the jettison operation does not affect the controllability of the aeroplane.

Jettisoning Procedure

Pilots of aircraft in flight are permitted to jettison fuel in an emergency. It must be borne in mind that fuel jettison is an emergency procedure to reduce aircraft mass expeditiously. The decision to jettison rests with the commander alone but the decision to jettison must be compatible with safety and the ability of the aeroplane to continue flying. When an aircraft operating within controlled airspace needs to dump fuel, the flight crew shall co-ordinate with ATC the following : route to be flown, which, if possible, should be clear of cities and towns, preferably over water and away from areas where thunderstorms have been reported or are expected, the level to be used, which should be not less than 1800 m (6000 ft) and the duration of the fuel dumping. If the use of flaps or slats adversely affects the jettisoning of fuel, their use during jettisoning must be prohibited, and a placard stating this must be positioned adjacent to the jettison control.

Safety

Unless there is an overriding requirement to jettison fuel, the aeroplane should be flown to an allocated area at an allocated height prior to commencing jettison. Consideration should be given to the weather conditions and areas of electrical storm activity should be avoided, as should areas of excessive turbulence. The no smoking light is to be illuminated and passengers briefed. ATC is to be informed that jettison is about to commence. Once jettison has begun, electrical switching should be restricted to essential use only, HF radio transmission suspended and VHF transmissions restricted to further emergency/flight safety communications only. The flow of fuel from the jettison vents is to be visually monitored (where possible) confirming flow started and flow stopped as required. During jettison manoeuvres should be smooth and the operation of flaps, slots or slats restricted to essential use only. Once the jettison is complete, ATC should be informed.

Fuel Jettison 17

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17 Questions

Questions

	1.	Where a fuel jettison system is fitted to an aeroplane it must be capable of:
		a.	reducing the aeroplane mass from max take-off mass to max landing mass in
			15 mins
		b.	reducing the aeroplane mass from max take-off mass to max landing mass in
			10 mins
		c.	reducing the aeroplane mass from max take-off mass to max landing mass in
			20 mins
		d.	reducing the aeroplane mass from max take-off mass to max landing mass in 5
			mins
	2.	Which of the following correctly describes the requirement of a fuel jettison
		system?
		a.	Free from fire hazards; discharges are clear of the aeroplane; fuel or fumes
			do not enter the aeroplane; control of the aeroplane is not affected by the
			jettison operation
		b.	Free from fire hazards; discharges are clear of the aeroplane; fuel or fumes do
			not enter the aeroplane; normal radio operation can continue
		c.	Free from fire hazards; discharges are clear of the aeroplane; fuel or fumes
			do not enter the aeroplane; must be safe to use in all weather/environmental
			conditions
		d.	The system must contain a protection device to stop the jettison as soon as
			the gear is lowered, and also to prevent all tanks being drained totally
	3.	Fuel jettison:
		a.	is a procedure to reduce mass in an emergency only
17		b.	is a procedure that may be employed to reduce aeroplane mass where an
			overweight landing may result in damage to the aeroplane
Questions		c.	may be authorized by ATC to reduce delays by protracted holding procedures
		d.	may be ordered by ATC to reduce aeroplane mass in an emergency situation
	4.	Fuel is to be jettisoned:
		a.	over the sea and then only above 10 000 ft
		b.	over the sea, or over land above 10 000 ft agl
		c.	anywhere and at any height if unavoidable in an emergency
		d.	over the sea, or over land above 4000 ft in summer or 7000 ft in winter
	5.	The following aeroplanes are required to have a jettison system:
		a.	all public transport aeroplanes
		b.	only public transport aeroplanes with MTMA greater than 5700 kg
		c.	all public transport aeroplanes requiring two pilots
		d.	all aeroplanes, except where the max landing mass exceeds the max take-off
			mass less the mass of fuel required for a 15 minute flight to land back at the
			aerodrome of departure

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Questions 17

6.When jettisoning fuel, safety is an overriding consideration. Which of the following lists correctly identifies items to be considered when planning to jettison fuel?

a.Smoking; HF Radio; operation of flaps/gear/slats; weather conditions

b.Height; speed; ATC clearance; weather; area

c.Time required; position; other aeroplanes; proximity of cloud; aeroplane attitude

d.OAT; wind direction; altitude; time of day; airspace restrictions; any other emergencies

7.Once jettison has begun:

a.passengers are restricted to their seats and strapped in

b.normal operation of flaps/gear and lift enhancers is permitted

c.HF radios may be used but limited to essential transmissions only

d.fuel flow from the vents is to be visually monitored (where possible)

8.Once the fuel jettison is complete:

a.it is essential that the fuel remaining is balanced in the tanks and a revised endurance calculated

b.ATC is to be informed that jettison is complete

c.the NO SMOKING light is to be extinguished

d.normal food distribution service is to recommence

Questions 17

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