Aircraft Deicing

Winter is coming, the formation of ice on top of the wing either during flight in cold area or after aircraft parked overnight in cold weather can alter the aerodynamic of the wing which can effect the lift force during take off.

To removed the ice & prevent it from reoccur, deicing fluid will be used which normally will be performed by well trained deicing team.

The commonly used fluid is either of ethylene glycol or propylene glycol however the latter is more common due to the fact it is less toxic.


Deicing fluid can be devided into 4 different type, type I, II, III & IV. Type II fluids are more commonly used and have thickening agent to prevent their immediate flow off aircraft surfaces. Typically the fluid film will remain in place until the aircraft attains 100 knots or so, at which point the viscosity breaks down due to sheer stress. The high speeds required for viscosity breakdown means that this type of fluid is useful only for larger aircraft.

Poor Maintenance Practices

I've found this while removing the right hand heat exchangers for cleaning. The clamp was"sitting" on top of the pneumatic duct.

It is posible that the ducts have been removed & reinstalled back with the top duct been normalised first, the lower duct then was reinstalled without the mechanic that done the installation aware of the contact.

All pneumatic, hydraulic, flight control cable must be inspected for interference with adjacent structures to eliminate unnecessary defect in the future. In the case above, due to vibration, crack can occur which will lead to pneumatic leakage and subsequent damage.

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.