Abstract: An example method of estimating a gas turbine engine surge margin and surge margin deterioration includes monitoring debris in at least a portion of an engine and establishing an estimated surge margin for the engine using information from the monitoring The method may use gas path parameters, such as pressures, temperatures, and speeds to establish the estimated surge margin. An example gas turbine engine surge margin assessment system includes a debris monitoring system configured to monitor debris moving through a portion of an engine, and a controller programmed to execute an engine deterioration model that establishes an estimated surge margin and loss in surge margin of the engine based on information from the debris monitoring system.

Abstract: An example method of estimating gas turbine engine performance deterioration includes monitoring debris in at least a portion of an engine and estimating performance deterioration of at least one component of the engine using information from the monitoring. The method may use gas path parameters, such as pressures, temperatures, and speeds to establish the estimated performance deterioration. An example gas turbine engine performance assessment system includes a debris monitoring system configured to monitor debris moving through a portion of an engine and a controller programmed to estimate performance deterioration of at least one component of the engine based on information from the debris monitoring system.

Abstract: An example method of assessing a component of a gas turbine engine includes monitoring debris in at least a portion of an engine and establishing an estimated thermal energy level for a component of the engine based on the monitoring. The method may use gas path parameters to establish the estimated thermal energy level. An example gas turbine engine component assessment system includes a debris monitoring system configured to monitor debris moving through a portion of an engine and a controller programmed to execute an engine deterioration model that assesses a thermal energy level of at least one component of the engine based on information from the debris monitoring system.

Abstract: A convertible gas turbine propulsion system operates in multiple output modes. The convertible gas turbine propulsion system comprises a gas generator, a first power turbine, a secondary propulsion system and an exhaust duct. The gas generator is configured to produce exhaust gas. The first power turbine is aligned with the gas generator to receive the exhaust gas. The secondary propulsion system is in series with the gas generator and the first power turbine. The exhaust duct coaxially extends from the first power turbine to the secondary propulsion system. The exhaust duct includes an exhaust port for opening the exhaust duct to ambient air pressure and permitting exhaust gas to bypass the secondary propulsion system. In various embodiments of the invention, the first power turbine is connected to a first rotary propulsion system, and the secondary propulsion system comprises a second power turbine or a nozzle.

Abstract: An actuation mechanism for use in a convertible gas turbine propulsion system comprises a plenum, a pneumatically powered drive body and a spring system. The plenum receives pressurized air from the convertible gas turbine propulsion system. The pneumatically powered drive body is connected to the plenum to receive pressurized air to axially move the drive body in a first direction. The spring system is connected to the drive body to axially move the drive body in a second direction.

Abstract: A turbine blade damper-seal assembly includes a seal nested within a damper such that both the seal and damper are disposed to provide sealing between adjacent blade platforms. The seal traverses the seal slot in the damper and seals the gap between adjacent blade platforms for the full axial length of the neck cavity between adjacent blades. The damper is located in an aft most position and includes features to facilitate vibration-dampening performance. The damper also includes features that cause entrapment between blades and therefore avoids the conventionally required protrusions on the blade to retain it in the assembled position.