28 Fuel Systems Flashcards
What type of fuel storage is on the aircraft?
Series of rubber bladder type cells and an integral tank in each wing connected by a cross feed line with a valve.
Where is the aux fuel tank located and what is its capacity?
Center sections of the wing and 79.5 Gallons.
What is the total usable fuel capacity?
539 gallons
What does the MAIN fuel system consist of?
Nacelle tank, 2 wing leading edge tanks, 2 box section tanks and an integral tank.
(6 total)
How is the outboard fuel delivered to the nacelle tank?
Via gravity.
How is fuel transferred from the aux system to the main system?
Via a jet pump mounted adjacent to the outlet strainer and drain in the aux cell.
How many sump drains are there for the main and aux systems?
5
How many drains does the nacelle have and what purpose?
2 at the bottom fwd side of the nacelle, inb drain is for standby boost pump and the outboard is for the nacelle sump.
The gravity feed line/tube has 1 drain valve where is this located?
aft outboard side of main landing gear structure.
How is the main and aux fuel system vented?
Through a recessed vent (to prevent icing) coupled to a static vent (heated to prevent icing) on the underside of the wing.
What happens in the event the recessed vent becomes blocked?
Your secondary static vent will take over venting the fuel system.
What prevents back flow from the nacelle tanks into the wing tanks?
A flapper type check valve located at the end of the gravity fed line.
What type of probes are used on the fuel system?
Fuel Capacitance probes
Explain the make up of the fuel capacitance probes.
Two concentric tubes, integral compensator located at the lowest point. (always suspended in fuel)
How does the capacitance fuel probe work?
The fuel in the space between the 2 tubes acts as the dielectric, the capacitance of the probe changes in relation to the dielectric (the fuel to air ratio in the tank)
What other factors can effect the capacitance of the probe?
Density changes in fuel manufacturers or temperature.
The fuel probe lengths are difference sizes to match the contour of the tank, why?
Provide linear capacitance vs volume in the tank at differing altitudes.
What can the integral compensator of the fuel probe sense?
Variations of the dielectrics constant cause by temperature change of the fuel.
When the empty capacitance test is carried out where should this be recorded?
airframe log book.
What needs to happen anytime a fuel probe is changed?
A new empty tank value will need to be established.
What are the preferred and alternate procedures of calibrating the fuel system?
Preferred - Empty tank, drained sumps.
Alternate - Fuel tanks at any level (Full Tanks) (or Level Fuel)
How do you carry out a leakage test of a fuel cell bladder?
Plug all openings, inflate with 1/4 PSI with a mixture of shop air an ammonia gas. check leakage with phenolphthalein solution.
What filter is added to the standby pump?
A noise filter to prevent interference.
Where are the fuel pump RF filters located?
1 each side next to the electrical standby pump.
How does the Aux system jet transfer pump get activated?
Via the engine driven boost pump which activates your motive flow valve.
When the switch for your AUX system is in AUTO what happens to your motive flow valve?
power is applied to the motive flow valve by your automatic fuel transfer module.
If you want to manually turn on your motive flow valve for AUX fuel transfer what must be done?
Place the switch into the AUX TRANSFER OVERIDE position.
When fuel is low in the AUX tank how is the motive flow valve turned off?
Via a low level float valve.
Does your crossfeed system feed fuel directly to the tank or the engine?
Engine.
Where are your firewall shut off valves located?
Behind the firewall on the inboard side.
Where is your crossfeed valve located?
inboard side of left wheel well.
What are installed close to your standby pump to prevent interference?
radio frequency filter.
What type of fuel indicating system is installed on the aircraft?
Capacitance type, compensated for specific gravity and reads in pounds on a linear scale.
What amount of fuel will bring on your L/R FUEL QUANTITY annunciator?
300 pounds giving you approx 30 minutes of flight time remaining.
What sequence is fuel indicating system carried out?
system ins, prob ins, system cap, probe cap, indicator test
