Abstract: A buffer seal arrangement is provided for improved buffer sealing of oil sump seals in gas turbine engines. The buffer seal arrangement includes a three section labyrinth seal. Disposed between the first and second section is a buffer air supply annulus for delivering pressurized air from the engine to said first and second sections of the seal. Oil drains are disposed between said second and third sections and adjacent the third section. The first section has four knife seals, and the second and third sections have three knife seals. Rig testing has shown that this buffer seal arrangement can prevent the leakage of oil into the gas path of the gas turbine engine.

Abstract: A drive for a variable crown shell roll in which a driven pinion provides rotary motion to the shell roll through the teeth of a first ring gear which is loosely mounted so as to be rockable about the pinion to accommodate deflection of a second ring gear flexibly carried by the roll shell and which meshes with the second ring gear.