AL-41 is “fuel system icing inhibitor” (FSII).
Jet fuel naturally has a small amount of suspended water. To help protect the water in the fuel from freezing, aircraft manufacturers usually will add some kind of fuel system to keep the jet fuel warm. As an added protection, some manufacturers also require that FSII is to be added to the fuel. There is a specific ratio for this mixture which is usually 0.06% – 0.15%
The main ingrident of FSII is DEGMME (diethylene glycol monomethyl ether). When mixed in with jet fuel it migrates to the small amount of water in jet fuel and lowers the water’s freezing point to -46 deg F. FSII has to be added to the fuel while fueling and cannot be added afterwards. FSII is heavier than fuel and will sink to the bottom of the tank and not mix in with the fuel.
The AL-41 also has some biocidal and pesitcide properities, so it can help kill bacterial growth in your fuel tanks.
Ona aerosol can can tread from 700...273 liter of jet fuel (0,06% ... 0,15% mixture), when refueling fuel flow rate is 228...114 l/min (30...60 GPM).