Abstract: A free turbine, gas turbine engine provided with a pre-swirl arrangement in the compressor, based on bleeding air from the compressor and using the bleed air as a pre-swirl device upstream of the compressor to increase its rotational speed. A governor device, driven from the compressor rotor, controls the amount of pre-swirl bleed air to maintain a constant compressor speed from minimum to maximum power. Compressor rotor and gas inertia effects during acceleration are thus eliminated.

Abstract: A method of troubleshooting, with a test set, an electronic fuel control system in an aircraft includes disconnecting the electronic engine control after mechanical tests have verified that the faults do not exist in the hydromechanical unit or associated mechanical parts. The test set then delivers signals to the circuits of the fuel control system one at a time to uniquely and specifically identify the fault. With this method, the engine can be tested when it is in its static condition.

Abstract: The disclosure teaches an improvement in a free turbine type engine which comprises a power limit unit. The unit includes a first sensor for measuring pressure at the turbine inlet, and a second sensor for measuring temperature at the turbine inlet. A third means provides a measurement indicative of turbine exhaust pressure and may be a sensor located in the exhaust duct which is downstream of the turbine or may comprise means for providing outside ambient pressure readily available from existing aircraft instrumentation, e.g., altimeter. A processor means calculates shaft horse power (SHP) from the above measurements. Other means are provided for generating a reference signal, and the reference signal is compared with SHP. When SHP is greater than the reference signal, then fuel to the engine is controlled to reduce engine power. The unit can also be adapted for calculating torque, and for reducing the torque when the torque is greater than the reference level.

Abstract: An airflow particle separator for a gas turbine engine provided for removing foreign particles and moisture from the air flow. The separator comprises an inner wall and an outer wall defining a passageway therebetween, with the inner wall including an inlet portion diverging in a downstream direction away from the separator axis while converging towards the outer wall to form a throat to accelerate incoming air to a higher velocity in a substantially axial direction. The inner wall then converges towards the separator axis and diverges from said outer wall with a splitter ring disposed between the inner and outer walls for splitting said passageway into inner and outer passages, with the outer passage adapted to bypass moisture and foreign particles. The leading edge of the splitter ring is located downstream and inward of said throat.

Abstract: A bearing support structure is provided in a gas turbine engine with a support structure mounted to the outer casing of the engine, and the structure defines an annular seat concentric with a rotating shaft. A cylindrical solid sleeve is seated in the annular seat so formed and extends axially therefrom in a cantilever manner and is provided with an outer bearing raceway for roller bearings, the outer raceway being constructed in out-of-round such that when the bearing structure is inserted in the outer raceway, it will assume a circular configuration providing a load on the roller bearings.