PRATT & WHITNEY PT6A 42 GENERATOR

In other words, you must be able to chop the power at the certified ceiling without the cabin altitude climbing. But, the rules require that the cabin pressure must be maintained when the engine power is low. When the engine is operating at cruise power, only a small portion of the compressed air must be bled to maintain the 6.2 psi cabin pressure and keep the TBM 850 cabin pumped up. The pressure is increased by each stage of the process. The PT6A Dash 66D engine in the 850 has four stages of axial compressors plus a final stage of centrifugal compression. The engine is used in over 100 different applications. The engine is arranged such that the power turbines are mounted inside the combustion chamber, reducing overall length.Д«y the 40th anniversary of its maiden flight in 2001, over 36,000 PT6As had been delivered, not including the other versions. The exhaust gas then escapes through two side mounted ducts in the power turbine housing, and is directed away from the engine in order to provide up to 600 lbf (2,700 N) of jet thrust. For turboprop use, this powers a two-stage planetary output reduction gearbox, which turns the propeller at a speed of 1,900 to 2,200 rpm.

PRATT & WHITNEY PT6A 42 GENERATOR

The hot gas from the gas generator section then flows into a separate power section of the engine, containing a single-stage power turbine driving the power take-off system at about 30,000 rpm. The air then flows into a single-stage centrifugal compressor, through the annular reverse-flow combustion chamber, and finally through a single-stage compressor turbine that powers the compressors at about 45,000 rpm. This has three stages on small and medium versions of the engine and four stages on large versions. In the gas-generator section air enters through an inlet screen into the low-pressure axial compressor. The engine consists of two sections that can be easily separated for maintenance.

Pratt & whitney pt6a 42