Abstract: A method of operating a gas turbine engine having an engine core having a turbine, a compressor, a combustor arranged to combust a fuel, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core; a fan shaft; a gearbox that receives an input from the core shaft and outputs drive to the fan via the fan shaft; a heat exchange system having at least one fuel-oil heat exchanger arranged to transfer heat to the fuel; and a fuel pump arranged to deliver the fuel to the combustor, wherein the fuel pump is located downstream of the at least one fuel-oil heat exchanger. The method includes operating the gas turbine engine using a fuel having a lubricity of between 0.71 mm and 0.90 mm wear scar diameter (WSD) at 25° C.

Abstract: A method of operating a gas turbine engine including an engine core including a turbine, compressor, combustor to combust a fuel, and core shaft connecting the turbine and compressor; a fan upstream of the engine core; a fan shaft; a gearbox that receives an input from the core shaft and outputs drive to the fan via the fan shaft; a primary oil loop system to supply oil to the gearbox; and a heat exchange system. The method includes controlling the heat exchange system to adjust fuel viscosity to be lower than or equal to 0.58 mm2/s on entry to the combustor at cruise conditions.

Abstract: This invention relates to an improved method for curing polyepoxide resins at elevated temperature and particularly to a method for reducing the time required to effect cure of thermosetting resins at elevated temperature without sacrificing performance. In the basic process, an epoxide resin comprising a polyglycidyl ether of a polyhydric phenol is contacted with methylenedianiline or derivative thereof, e.g., methylenedianiline and di(3-methyl-4-aminophenyl)methane in an amount sufficient to effect cure of the polyepoxide resin at an initial temperature and then raised to a final cure temperature. The improvement for reducing the time necessary for cure comprises:effecting an initial and partial cure of the epoxy resin at a temperature between 90.degree. and 130.degree.

Abstract: This invention relates to an improved method for curing polyepoxide resins at elevated temperature and particularly to a method for reducing the time required to effect cure of thermosetting resins at elevated temperature without sacrificing performance. In the basic process, an epoxide resin comprising a polyglycidyl ether of a polyhydric phenol is mixed with cycloaliphatic amine, e.g., di(4-aminocyclohexyl)methane, di(4-amino-3-methylcyclohexyl)methane, and isophoronediamine in an amount sufficient to effect cure of the polyepoxide resin at an initial temperature and then raised to a final cure temperature. The improvement for reducing the time necessary for cure comprises:effecting an initial and partial cure of the epoxy resin at a temperature between 60.degree. and 100.degree. C.

Abstract: This invention pertains to epoxy resins having increased chemical resistance to solvents, and good cured mechanical properties which are prepared by curing the epoxy resins with a curing agent comprising a mixture of methylene bridged poly(cyclohexyl-aromatic)amines. The methylene bridged poly(cyclohexyl-aromatic)amine curing agents are the residue obtained from the distillation of a mixture of poly(cyclohexylaromatic)amines formed by the hydrogenation of crude methylenedianiline or crude di(4-amino-3-methylcyclohexyl)methane.