One issue with the PA46 is the minimum ice penetration speed of 135 knots. Vy is 125 on the meridian. It is in place to prevent ice accumulation on the unprotected undersides of the wings and tailplane.
Taken with possible misuse of the IS, if there was serious icing, there is a lot for an inexperienced pilot of the aircraft to think about in a busy terminal environment..
Apparently the local rag says they have seen a Skyguide paper saying that the PA46 was returning due to icing.
Neil, yes, that is what I meant and the risk I was raising concerning torque.
We seem to have confusion between OPEN and CLOSED.
Jason’s usage of the word open means suitable for flying in icing, Quatrelle’s using the term closed to mean the same thing.
It sounds like the system on a PT6. You do have to be careful when you come out of icing and you decide to lose the anti icing, because the torque goes up, and you could in some circumstances over torque the gearbox.
Yes, activating the IS reduces the airflow into the engine with a corresponding reduction of torque, and increase in ITT. In my Jetprop it is around 100-120 Lbs of torque, and closing it again gives you the reverse.
The FCU does not compensate for this. You manually have to adjust the throttle to bring the torque back to where you want it. It is very similar in principle to alternate air operation with a piston engine.
The advantage over the constant IS design is the extra power and fuel economy during the time you do not need to activate IS, which is probably 70%+ of the time depending on the weather. The disadvantage is that it is an additional system for the pilot to manage.
I have gotten so used to its operation and incorporated it into my SOP that I do not really see it as any kind of burden.
Cheers. E
I think it is my terminology. With the intertial sep open, some intake air is diverted reducing torque correct?
Equally closing the inertial sep adds more air to the intake increasing power no?
Or does the FCU maintain the set torque but temps change?
Maybe this is why I fly a Meridian! 
Jason says…’ The risk in the Jetprop is not using the ice door correctly //If you close it with high power set, you can overtorque the engine’
Sorry Jason thats completely the wrong way round.
On the Jetprop whatever torque you have set it is reduced by 150lbs when you close the internal separator, power is decreased not increased.
One of the advantages of having a manually selected internal separator is that once clear of cloud in the climb one has reduced fuel burn at the same torque setting and 150lbs of free torque in the cruise (if clear of cloud).
Denopa says ….to go full power, and I assumed this would be true in the JP, leaving no margin for increased torque. That was based on comments made by JP owners on the MMOPA forums….
On the Meridian/Jetprop/TBM the climb torque setting is made with only part throttle, just as on a piston aircraft the throttle is increased to maintain climb torque as air density decreases….full throttle would not be used until somewhere above FL200 depending on air temp.
There is more risk of over temping than over torquing when using the inertial separator (IS) on the JP due to the reduction in direct airflow.
My standard SOP is to leave the IS on from just after startup to 10,000’ and on again at top of descent until shut down and just prior to entry into any kind if visible moisture. This would also be the time for prop heat.
Hopefully covers FOD and bird strikes as well as any initial climb ice ingestion potential.
Once you get into the habit of its use, it is a non event to manage, and there is no real loss of performance unless you remain in IMC past the 10k point and have to keep it on, in which case the climb rate will suffer as you will most certainly be ITT limited. In practise this is more of an issue here in Asia with our high ground OAT’s than in Europe.
The excess power of these aircraft compared to the weight ratio is significant. I have never really felt having a manually actuated IS was any kind of disadvantage. I much prefer it to be my decision when to use it.
Watching that video is pretty sickening… It is looking more like a Visual to IMC type disorientation event. Very tragic.
The risk in the Jetprop is not using the ice door correctly rather than a loss of power due to its use. If you forget to use it you could have a situation which is suspected in the TBM-850 accident least year. If you close it with high power set, you can overtorque the engine. No evidence that this had anything to do with the accident here though.
My attitude to that changed after having had to replace two cylinders due to sand in the engine… I’m still not sure what caused that.
quatrelle, that’s a very interesting point. In the Mirage my sop if encountering worrying ice in the climb is to go full power, and I assumed this would be true in the JP, leaving no margin for increased torque. That was based on comments made by JP owners on the MMOPA forums, but I know nothing of turbine operations so I must have misunderstood. That’s good news, I thought this was a definite advantage of the Meridian over the JP…
