Fan bearing support system for gas turbine engine with power gearbox

A turbine engine comprising:

• a turbine section defining a centerline, the turbine section including a turbine shaft rotatable about the centerline;
• a fan section including a fan rotor, a hub coupled to the fan rotor, and fan blades coupled to the hub, the fan section rotatable about the centerline, the hub having a diameter D1 and the fan section having a second diameter D2, wherein D1/D2 defines a fan hub ratio;
• a power gearbox including an epicyclic gear assembly including a sun gear, planetary gears, and a ring gear, the turbine shaft coupled to one gear of the epicyclic gear assembly, and the fan rotor coupled to another of the gears of the epicyclic gear assembly;
• and
• a fan rotor bearing support system including a first bearing assembly and a second bearing assembly, the first bearing assembly including a four point ball bearing including balls, an inner race secured to the fan rotor adjacent to the power gearbox and an outer race secured to stationary support structure of turbine engine, the second bearing assembly including a roller bearing including an inner race secured to the fan rotor and an outer race secured to the support structure of the turbine engine, the second bearing assembly positioned distally of the first bearing assembly and proximally of the fan hub, wherein the fan hub ratio is between 0.25 and 0.40, wherein the first bearing assembly has a tight bearing configuration with a clearance between the balls and the inner and outer races of the first bearing assembly of between 5 mil and 10 mil.

A turbine engine comprising:

• a turbine section defining a centerline, the turbine section including a turbine shaft rotatable about the centerline;
• a fan section including a fan rotor, a hub coupled to the fan rotor, and fan blades coupled to the hub, the fan section rotatable about the centerline, the hub having a diameter D1 and the fan section having a second diameter D2, wherein D1/D2 defines a fan hub ratio;
• a power gearbox including an epicyclic gear assembly including a sun gear, planetary gears, and a ring gear, the turbine shaft coupled to the epicyclic gear assembly, and the fan rotor coupled to another of the gears of the epicyclic gear assembly;
• and
• a fan rotor bearing support system including a first bearing assembly and a second bearing assembly, the first bearing assembly including a four point ball bearing including balls, an inner race secured to the fan rotor adjacent to the power gearbox and an outer race secured to stationary support structure of turbine engine, the first bearing assembly has a tight bearing configuration with a clearance between the balls and the inner and outer races of between 5 mil and 10 mil., the second bearing assembly including a roller bearing including an inner race secured to the fan rotor and an outer race secured to the support structure of the turbine engine, the second bearing assembly positioned distally of the first bearing assembly and proximally of the fan hub, wherein the fan hub ratio is between 0.25 and 0.40, wherein the first bearing assembly has a tight bearing configuration with a clearance between the balls and the inner and outer races of the first bearing assembly of between 5 mil and 10 mil.