A gas turbine engine according to an example of the present disclosure includes, among other things, a fan section, a compressor section, and a turbine section including a fan drive turbine that drives the fan through a gear reduction. The gear reduction includes at least two double helical gears in meshed engagement, each of the at least two double helical gears having a first plurality of gear teeth separated from a second plurality of gear teeth such that a first end of the first plurality of gear teeth and a first end of the second plurality of gear teeth are spaced apart by an axial distance. Each of the first plurality of gear teeth is offset a first circumferential offset distance in relation to the next gear tooth of the second plurality of gear teeth when moving in a circumferential direction relative to respective axes.

A gas turbine engine according to an example of the present disclosure includes, among other things, a fan section, a compressor section, and a turbine section including a fan drive turbine that drives the fan through a gear reduction. The gear reduction includes at least two double helical gears in meshed engagement, each of the at least two double helical gears having a first plurality of gear teeth separated from a second plurality of gear teeth such that a first end of the first plurality of gear teeth and a first end of the second plurality of gear teeth are spaced apart by an axial distance. Each of the first plurality of gear teeth is offset a first circumferential offset distance in relation to the next gear tooth of the second plurality of gear teeth when moving in a circumferential direction relative to respective axes.

An engine driven environmental control system (ECS) air circuit includes a gas turbine engine having a compressor section. The compressor section includes a plurality of compressor bleeds. A selection valve selectively connects each of said bleeds to an input of an intercooler. A second valve is configured to selectively connect an output of said intercooler to at least one auxiliary compressor. The output of each of the at least one auxiliary compressors is connected to an ECS air input.

An engine driven environmental control system (ECS) air circuit includes a gas turbine engine having a compressor section. The compressor section includes a plurality of compressor bleeds. A selection valve selectively connects each of said bleeds to an input of an intercooler. A second valve is configured to selectively connect an output of said intercooler to at least one auxiliary compressor. The output of each of the at least one auxiliary compressors is connected to an ECS air input.

A fully compounding rotorcraft includes a fuselage having first and second wings extending therefrom and configured to provide lift compounding responsive to forward airspeed. A twin boom includes first and second tail boom members that extend aftward from the first and second wings. An empennage is coupled between the aft ends of the tail boom members. An anti-torque system includes a tail rotor that is rotatably coupled to the empennage. An engine is disposed within the fuselage and is configured to provide torque to a main rotor assembly via an output shaft and a main rotor gearbox. An auxiliary propulsive system is coupled to the fuselage and is configured to generate a propulsive thrust to offload at least a portion of a thrust requirement from the main rotor during forward flight, thereby providing propulsion compounding to increase the forward airspeed of the rotorcraft.

A fully compounding rotorcraft includes a fuselage having first and second wings extending therefrom and configured to provide lift compounding responsive to forward airspeed. A twin boom includes first and second tail boom members that extend aftward from the first and second wings. An empennage is coupled between the aft ends of the tail boom members. An anti-torque system includes a tail rotor that is rotatably coupled to the empennage. An engine is disposed within the fuselage and is configured to provide torque to a main rotor assembly via an output shaft and a main rotor gearbox. An auxiliary propulsive system is coupled to the fuselage and is configured to generate a propulsive thrust to offload at least a portion of a thrust requirement from the main rotor during forward flight, thereby providing propulsion compounding to increase the forward airspeed of the rotorcraft.

An oil system for a gas turbine engine includes an oil pump driven by a gear train having a main input drive gear rotating when a propulsor rotor rotates. The gear train includes two sets of gears joined by two connection shafts each having a clutch. The first set of the gears include a forward input gear and a reverse input gear each driven by the main input drive gear. The forward and the reverse input gears drive a pinion gear in the second set of gears through a clutch. Each clutch transmits rotation driven in a same driving direction and slips in an alternate driving direction. The first set of the gears has an even number of the gears, and the second set of the gears has an odd number of the gears.

An oil system for a gas turbine engine includes an oil pump driven by a gear train having a main input drive gear rotating when a propulsor rotor rotates. The gear train includes two sets of gears joined by two connection shafts each having a clutch. The first set of the gears include a forward input gear and a reverse input gear each driven by the main input drive gear. The forward and the reverse input gears drive a pinion gear in the second set of gears through a clutch. Each clutch transmits rotation driven in a same driving direction and slips in an alternate driving direction. The first set of the gears has an even number of the gears, and the second set of the gears has an odd number of the gears.

A dual flow turbine engine includes at least one lubricant tank located in an annular space of the turbine engine body and at least one hatch which is provided on an external cowling of a nacelle, for filling the tank. The tank is configured to be filled, by means of a removable tubular pipe inserted from the hatch into the tank, through canisters. One of the canisters includes a first interface through which the pipe is configured to pass, and another canister includes a second interface for connecting the pipe to the tank.

A gas turbine engine includes a fan with a plurality of fan blades rotatable about an axis, a compressor section, a combustor in fluid communication with the compressor section, and a turbine section in fluid communication with the combustor. The fan defines a fan diameter and the turbine section includes a fan drive turbine with a diameter less than 0.50 the size of the fan diameter. A geared architecture is driven by the turbine section for rotating the fan about the axis.