Abstract: An apparatus has: a first member; a shaft rotatable relative to the first member about an axis; and a seal system. The seal system has: a seal carried by the first member and having a seal face; a seal housing; a seat carried by the shaft and having a seat face in sliding sealing engagement with the seal face; and a plurality of coil springs biasing the seal face against the seat face, each coil spring having a first end and a second end. The seal has a plurality of spring compartments. Each of the plurality of coil springs is partially within a respective associated compartment of the plurality of spring compartments.

Abstract: An exemplary gas turbine engine assembly includes a fan section including a fan, a first spool having a first turbine operatively mounted to a first turbine shaft, and a second spool having a second turbine operatively mounted to a second turbine shaft. The first and second towershafts are respectively coupled to the first and second turbine shafts. An accessory drive gearbox includes a set of gears. A compressor is driven by the first towershaft. A transmission couples a starter generator assembly to the set of gears. The transmission is transitionable between a first mode where the starter generator assembly is driven at a first speed relative to the second towershaft in response to rotation of the second towershaft, and a second mode where the starter generator assembly is driven at a different, second speed relative to the second towershaft in response to rotation of the second towershaft.

Abstract: A bearing compartment seal for a gas turbine engine includes a seal ring that defines an axis and has a radially inward facing sealing surface. A seal runner is configured to rotate relative to the seal ring. The seal runner has a runner surface facing the radially inward facing sealing surface. A plurality of grooves are spaced circumferentially along the runner surface. The plurality of grooves have a length in an axial direction that is at least 50% of an axial length of the runner surface.

Abstract: A seal assembly includes a housing that includes a seal flange at least partially defining a seal opening. A carbon seal is located at least partially in the seal opening and includes a first axially facing surface. The seal flange includes an axially facing surface that has a carbide based coating and a diamond-like carbon coating in engagement with the first axially facing surface on the carbon seal.

Abstract: A seal assembly includes a carbon seal that has a sealing surface. A seal seat has a sealing surface and is positioned for rotation relative to the carbon seal. A diamond-like carbon coating at least partially forms the sealing surface on the seal seat.

Abstract: A bearing compartment seal for a gas turbine engine includes a seal ring that defines an axis and has a radially inward facing sealing surface. A seal runner is configured to rotate relative to the seal ring. The seal runner has a runner surface facing the radially inward facing sealing surface. A plurality of grooves are spaced circumferentially along the runner surface. The plurality of grooves have a length in an axial direction that is at least 50% of an axial length of the runner surface.

Abstract: A seal assembly includes a housing that includes a seal flange at least partially defining a seal opening. A carbon seal is located at least partially in the seal opening and includes a first axially facing surface. The seal flange includes an axially facing surface that has a carbide based coating and a diamond-like carbon coating in engagement with the first axially facing surface on the carbon seal.

Abstract: A seal assembly includes a carbon seal that has a sealing surface. A seal seat has a sealing surface and is positioned for rotation relative to the carbon seal. A diamond-like carbon coating at least partially forms the sealing surface on the seal seat.

Abstract: A bearing compartment seal for a gas turbine engine includes a seal ring that defines an axis and has a radially inward facing sealing surface. A seal runner is configured to rotate relative to the seal ring. The seal runner has a runner surface facing the radially inward facing sealing surface. A plurality of grooves are spaced circumferentially along the runner surface. The plurality of grooves have a length in an axial direction that is at least 50% of an axial length of the runner surface.

Abstract: A seal assembly includes a housing at least partially defining a seal opening and at least partially surrounding a rotatable shaft. A carbon seal is located at least partially in the seal opening and includes a sealing surface. The rotatable shaft includes a radially facing surface that has a carbide based coating and a diamond-like carbon coating in engagement with the sealing surface on the carbon seal.

Abstract: An assembly includes a housing, a carrier, a spring element and a seal element. The housing includes a bore and an annular groove that extends axially along a centerline into the housing from the bore. The carrier projects axially along the centerline into the annular groove. The carrier is configured to translate axially along the centerline relative to the housing. The spring element is arranged within the annular groove. The spring element is configured to bias the carrier axially away from the housing along the centerline. The seal element is mounted to the carrier and arranged within the bore.

Abstract: An apparatus has: a first member; a shaft rotatable relative to the first member about an axis; and a seal system. The seal system has: a seal carried by the first member and having a seal face; a seal housing; a seat carried by the shaft and having a seat face in sliding sealing engagement with the seal face; and a plurality of coil springs biasing the seal face against the seat face, each coil spring having a first end and a second end. The seal has a plurality of spring compartments. Each of the plurality of coil springs is partially within a respective associated compartment of the plurality of spring compartments.

Abstract: Apparatus and associated methods relate to a segmented radial seal assembly that includes at least two segments, each segment having a first end and a second end at opposite ends. A first segment first end has a protruding feature and defines a tangential vector from a circumferential ring that is formed by the segmented radial seal. The protruding feature defines a curved face having at least a first axis of curvature that is parallel to the tangential vector. The second segment second end has a recessed feature that is matingly engageable to the first segment first end, thereby forming a first radial seal segment joint. The segmented radial seal assembly is configured to surround a shaft.

Abstract: A seal housing may comprise an aft flange, an outer diameter (OD) ring and a stopper. The stopper may extend radially inward from a radially inner surface of OD ring. The stopper may be configured to interface with a monobloc carbon seal. The stopper may comprise a circumferential stopping portion and an axial stopping portion. There may be a plurality of the stopper.

Abstract: An exemplary gas turbine engine assembly includes a fan section including a fan, a first spool having a first turbine operatively mounted to a first turbine shaft, and a second spool having a second turbine operatively mounted to a second turbine shaft. The first and second towershafts are respectively coupled to the first and second turbine shafts. An accessory drive gearbox includes a set of gears. A compressor is driven by the first towershaft. A transmission couples a starter generator assembly to the set of gears. The transmission is transitionable between a first mode where the starter generator assembly is driven at a first speed relative to the second towershaft in response to rotation of the second towershaft, and a second mode where the starter generator assembly is driven at a different, second speed relative to the second towershaft in response to rotation of the second towershaft.

Abstract: A seal assembly includes a carbon seal that has a sealing surface. A seal seat has a sealing surface and is positioned for rotation relative to the carbon seal. A diamond-like carbon coating at least partially forms the sealing surface on the seal seat.

Abstract: A seal assembly includes a housing that includes a seal flange at least partially defining a seal opening. A carbon seal is located at least partially in the seal opening and includes a first axially facing surface. The seal flange includes an axially facing surface that has a carbide based coating and a diamond-like carbon coating in engagement with the first axially facing surface on the carbon seal.

Abstract: A seal assembly includes a housing at least partially defining a seal opening and at least partially surrounding a rotatable shaft. A carbon seal is located at least partially in the seal opening and includes a sealing surface. The rotatable shaft includes a radially facing surface that has a carbide based coating and a diamond-like carbon coating in engagement with the sealing surface on the carbon seal.

Abstract: Apparatus and associated methods relate to a segmented radial seal assembly that includes at least two segments, each segment having a first end and a second end at opposite ends. A first segment first end has a protruding feature and defines a tangential vector from a circumferential ring that is formed by the segmented radial seal. The protruding feature defines a curved face having at least a first axis of curvature that is parallel to the tangential vector. The second segment second end has a recessed feature that is matingly engageable to the first segment first end, thereby forming a first radial seal segment joint. The segmented radial seal assembly is configured to surround a shaft.

Abstract: Aspects of the disclosure are directed to a rotatable shaft, and a plurality of bearings coupled to the rotatable shaft, where the plurality of bearings include a first bearing, a second bearing, and a third bearing, where the first bearing defines an axial first bearing centerline, where the second bearing defines an axial second bearing centerline, where the third bearing defines an axial third bearing centerline, and where the axial second bearing centerline is radially offset from the axial first bearing centerline and the axial third bearing centerline.