Old 19th Aug 2015, 01:53
  #57 (permalink)  
Join Date: Apr 2008
Location: Australia
Posts: 659
yr right,
You claim to be an engineer with expertise on PT6 engines. You may want to brush up on a few things.

Yes and that is why the Tq limiter is set and comes in at around 104% ish NG
There is no torque limiter on the PAC 750 engine. You probably haven't worked on this aircraft, so I will forgive you that one. But, if there was, it would be based on a torque value, not an Ng speed value.

Being based on a torque value, rather than an Ng speed means that differing ambient conditions would see the torque limiter activate at different engine speeds. On a cold day at low elevation, for example, it could activate at 100.0%. On a hot day at high elevation, it may not activate until 102%.

These are theoretical numbers, not based on any particular engine. I relate them to convey the general relationship between torque and Ng.

The over speed dose not allow you to exceed itt though.
There is nothing on any of the PT6 variants that prevents you from exceeding ITT. The primary and secondary prop governors, plus the "fuel topping" governor, are all about preventing overspeed of the power turbine.
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