Refueling Control Panel

This is the place where control for refueling process took place. Located at the forward edge of right hand lower surfaces. Amount of fuel required base on the flight plan will be routed to certain tanks by controlling the switch of each tank. What unique about BBJ is that, there is additional control for auxiliary fuel tank which is located in forward and aft cargo compartment.

Normally the wing tank will be filled up first followed by the center tank, any extra fuel required then will be routed to the auxilliary tank. Depend on the density of the fuel for that day (fuel density varies mainly due to temperature) the maximum quantity for each wing tank is 3800 kg (4800 liters) and center tank 12750 kg (16200 liters). For auxilliary tank, on BBJ that i work on it has 1 auxiliary tank at the forward cargo and 3 tank in the aft cargo, each can be filled up to 1500 kg (1900 liters) and 2900 kg (3600 liters) respectively.

In each tank there is an instrument that will measure the capacitance of the fuel and from that through fuel processing unit will convert it to kilogram. Weight of the fuel is more relevant for aircraft as it will be added to total weight of an aircraft to determine take off thrust setting for engine for that particular flight.

Pre Refueling - Water Check

Prior to carry out refueling of an aircraft, the quality of the fuel from the fuel truck (bowser) must be checked to ensure it cleanliness as well as the present of water. Dirty fuel can caused fuel filter clogged and water can frezzed at high altitude during flight thus blocking the fuel going to the engine.

Normally at the bowser, there a small glass container in which fuel sample from the bowser can be collected. Visually we can check the cleanliness. To check for presence of water, we need to use the water detector capsule.

With water detection capsule attached at the front of the shringe, the fuel that been suck will pass through it. The capsule contain chemical that will change colour when exposed to water molecule.

If no water molecule present in the fuel, the capsule colour will remain unchanged from the original which light yellow.

This is what happen when the water introduced to the capsule. Turned dark blue which indicate the present of water.

So far i never had an experience this test failed from most of the fuel supplier around the world, aircraft fuel is high quality kerosene that been processed through very strict high quality standard to ensure safety operation of an aircraft.

Thanks to Benny from Cotonou, Benin which coorperate & enable me to take the photo of the test.

Auxilliary Fuel Tank

BBJ (Boeing Business Jet) can travel longer range compared to conventional 737 due to this extra fuel tank added in its cargo hold.

Depend on certain configuration per customer specific need, this extra tank can be placed at aft area of the forward cargo or forward area of aft cargo hold. This is to ensure center of gravity of the aircraft remain close to the center of the aircraft.

Each tank can hold around 1800 liters of fuel which if converted to kilograms will be around 1500 kg except the master tank which will have much higher capacity.

All fuel from auxiliary tank will be routed to the center tank of the aircraft before goes to the engines. What unique about this system is, fuel from auxiliary tank is "pump" to center tank using differential pressure from the cabin which will start once fuel in center tank dropped to certain level.

During initial refueling before the flight, the fuel will be added to the wing & center tank fuel first, extra fuel required for the flight then will be filled up in this auxiliary tank.

It's hard to see how this aux tank looks like, i found this extra tank kept in the store, it has been removed form one of the BBJ due extra cargo space required for the baggage. if you need extra range for the distance, cargo space has to be sacrifice for the fuel tank...

CFM Engine Using BioFuel

BBJ is using CFM56-27 engine for it propulsion system, what i want to highlight here is in June 2007, the engine manufacturer CFM International has successfully carried out an initial test of a CFM56-7B engine using an ester-type biofuel at Snecma’s Villaroche facility near Paris.

CFM56 engines are produced by CFM International (CFM), a 50/50 joint company of Snecma (SAFRAN Group) and General Electric Company.

The biofuel used for this test is 30 % vegetable oil methyl ester blended with 70 % conventional Jet-A1 fuel. This test was designed to check the operation of a jet engine using a fuel made from biomass, without making any technical changes to the engine. With this type of biofuel, the target is a net reduction of 20 percent in carbon dioxide (CO2) emissions compared with current fuels.

CFM is running engine tests to develop solutions based on mixtures of jet fuel and second-generation biofuels. For instance, it is currently focusing on the evaluation of alternative fuels made using biomass (offering properties closer to those of jet fuel), which also offer better environmental performance.

For alternative fuels to be used in the aviation industry, there are a number of major technology challenges that must be met, including energy density, thermal stability (avoiding coking at high temperature), use at very low temperatures (freezing) or high temperatures, lubricating effect with materials used, and the availability of mass production facilities worldwide.

Even though it is only 30% "vegetable oil" as a start, it is a major step toward greener emission from aviation industry.

Refueling the aircraft.

How many of us really knows how refueling of an aircraft is done and where is the fuel tank for an aircraft is located? Probably not many know as well what type of fuel aircraft used. Aircraft fuel which is basically a highest grade kerosene will be pumped up by the fuel truck using the hose connected to the refueling panel.



At the fueling panel which is normally on right hand side of the aircraft wing's on majority of the aircraft, there is a control switches that open and close shut-off valve for each tank that fuel have to be added to achived total amount of fuel required for flight.

Aircraft fuel tank in general devided in to 3 main area, inside both wings itself as well as under the fuselage which is inside the body of the aircraft itself. Fuel tank in the wings will be filled up first before the fuselage. If happen that you sit in the middle of the aircraft next to the wing area, take not that below your feet is where the fuel tank is located.

R/H Boost Pump Wire Burned.

Last week, mission from Riyadh to Melbourne, transit stop in Kuala Lumpur for 1 hr after 7 hrs flight. 2 hrs after airborne, the pilot called me to the cockpit and informed me that R/H aft boostpump Low Pressure light came on. As per crew checklist boost pump switch to be kept off.

Upon landing in Melbourne, noticed that the boost pump CB's in P62 PDP popped-out. Inspected the boost pump looks normal, however when i traced the wiring found burned wire about 1 ft from the pump itself. Defect put under MEL cat C, upon return to base, damaged wire repaired per Standard Wiring Practice Manual.

It is quite mysterious how the wires got burned, lightning strike? Landing was retracted as it happen 2 hrs after airborne. I noticed adjacent bolt to the burn area, probably arcing could be the caused.