Abstract: A method for balancing rotating machinery, such as gas turbine engines, to minimize vibrations. The method involves operation of the engine for a period of time at varying power levels and ranges of other operational parameters representative of the system operating envelope to obtain vibration data (amplitude and phase) for the full range of dynamic responses of interest. This usually includes time at elevated power settings until the engine reaches thermal stability, altitude variation, etc. as well as the full engine operating range. The full set of vibration data measured during the engine run is analyzed to generate unique unbalance states. The unique unbalance states are then analyzed and the mean unbalance state is identified. Balancing masses can then be installed or removed in accordance with a balance solution that is equal and opposite to the mean unbalance state.

Abstract: A method for balancing rotating machinery, such as gas turbine engines, to minimize vibrations. The method involves operation of the engine for a period of time at varying power levels and ranges of other operational parameters representative of the system operating envelope to obtain vibration data (amplitude and phase) for the full range of dynamic responses of interest. This usually includes time at elevated power settings until the engine reaches thermal stability, altitude variation, etc. as well as the full engine operating range. The full set of vibration data measured during the engine run is analyzed to generate unique unbalance states. The unique unbalance states are then analyzed and the mean unbalance state is identified. Balancing masses can then be installed or removed in accordance with a balance solution that is equal and opposite to the mean unbalance state.

Abstract: A method for balancing rotating machinery, such as gas turbine engines, to minimize vibrations. The method involves operation of the engine for a period of time at varying power levels and ranges of other operational parameters representative of the system operating envelope to obtain vibration data (amplitude and phase) for the full range of dynamic responses of interest. This usually includes time at elevated power settings until the engine reaches thermal stability, altitude variation, etc. as well as the full engine operating range. The full set of vibration data measured during the engine run is analyzed to generate unique unbalance states. The unique unbalance states are then analyzed and the mean unbalance state is identified. Balancing masses can then be installed or removed in accordance with a balance solution that is equal and opposite to the mean unbalance state.

Abstract: Bi-directional nacelle ventilation and cooling systems for use with aircraft and related methods are disclosed. An example apparatus includes a passageway to fluidly couple an opening formed in a nacelle of an aircraft engine and an engine compartment of the nacelle. The opening provides an inlet into the engine compartment when passive airflow is available to vent or cool the engine compartment and the opening to provide an outlet from the engine compartment when forced air is needed to vent or cool the engine compartment. A fan is positioned in the passageway to provide the forced air when the passive air is unavailable.

Abstract: A method for balancing vibrations in a rotating machine is provided. The rotating machine has a first and a second plane of imbalance. The method includes determining a first set of solution mass vectors that includes a first solution mass vector for the first plane and a first solution mass vector for the second plane. Each first solution mass vector includes a mass and a phase angle. A first phase difference between a phase angle of the first solution mass vector for the first plane and a phase angle for the first solution mass vector for the second plane is calculated. The first phase difference is compared to a pre-selected value. If the first phase difference is less than the pre-selected value, the first set of solution mass vectors is retained. The first set of solution mass vectors is then incremented to create a second set of solution mass vectors that includes a second solution mass vector for the first plane and a second solution mass vector for the second plane.