Part 4
Page 4
FUEL SYSTEM MALFUNCTIONS
Fuel Tank Venting
9. The Number 3 tanks are normally full prior to flight. Therefore these
tanks should be the only tanks to indicate signs of venting. In this
event, transfer the excess fuel to the adjacent Number 2 tank using the
Number 3 tank fuel pump.
Fuel Pump Gland Drain Leak
10. This fault indicates unserviceability of the associated fuel pump.
Further investigation must be undertaken by an appropriate trade
specialist. Aircrew may consider tripping the circuit protection to
prevent inadvertent operation of the pump.
Abnormal Fuel Pump Load
11. Normal fuel pump load is 4A to 7A. A fuel pump which indicates
current consumption below 4A or above 7A is abnormal and requires
further investigation. An abnormal reading is unacceptable for a Number
1 or Number 2 tank pump. If the Number 3 tank pump is affected then
although it is not required for direct engine feed, this would render the
fuel in that tank and its opposite tank as unusable and cause excessive
fatigue on landing due to the increased residual weight.
Fuel Pressure Warning Light On
12. The Fuel Low Pressure Warning Lights normally extinguish as
the RPM increases during the start sequence. If, at 1200RPM, the
appropriate light remains on then the selected fuel tank pump should
be switched on. If the light subsequently extinguishes this could be
indicative of a malfunction associated with the engine driven fuel pump.
Rectification of such a fault requires investigation by a trade specialist.
If the light remains on after switching the required fuel pump on, and
as long as there is no evidence of actual fuel leak from the engine, a
malfunction of the fuel pressure switch may be the cause. A change of
pressure switch should be considered prior to flight as without it primary
indication of engine fuel system malfunction is lost.
UNCONTROLLED DOCUMENT - NOT FOR USE IN FLIGHT OR TO BE PRINTED
UNCONTROLLED DOCUMENT - NOT FOR USE IN FLIGHT OR TO BE PRINTED