GAS TURBINE ENGINE WITH A FLUID COOLER

A fluid cooler (30) for a gas turbine engine (10) includes an outer tube (32) having an outer tube inlet (40) at a first end (36) of the fluid cooler and an outer tube outlet (42) at a second end (38) of the fluid cooler (30). A primary axis (48) of the fluid cooler (30) is defined within the outer tube (32) between the first and second ends (36, 38) of the fluid cooler (30). A plurality of inner tubes (34) extend within the outer tube (32) between the first second ends (36, 38) of the fluid cooler (30). The inner tubes (34) have a common inner tube inlet (50) and a common inner tube outlet (52). The inner tubes (34) extend helically about the primary axis (48). A first group of the inner tubes (34) are disposed at a first radius (R1) from the primary axis (48) and a second group of the inner tubes (34) are disposed at a second radius (R2) from the primary axis (48), the second radius (R2) different from the first radius (R1).