a gas turbine engine and an accessory gear box are provided for . the gas turbine engine comprises a drive shaft , a compressor , a combustor and an exhaust turbine , where the exhaust turbine and the compressor are coaxially connected by the drive shaft . the gas turbine engine further comprises an engine casing of varying diameters circumferentially enveloping the compressor , the combustor and the exhaust turbine with a waist located between the compressor and the combustor . the gas turbine engine also includes an accessory gear box attached to the engine casing at the waist , the agb comprising a gear rotating on an axis extending in a transverse direction relative to that of the drive shaft .