TBM850 loosing power climbing around FL200

[G550flyer 1,014]

11 minutes ago, Flyfaster_MTN002 said:

Never see squirrels or porpoises even with the awful AP we have

The DC10, GIII, GV and G550 become real pitch sensitive when we swap from indicated airspeed mode to MACH mode of the IAS/FLCH. Most jets will swap to MACH speeds around 28500 to 29500(MACH change over). One day I sat and watched how bad it would get and the DC10 got pretty bad. It usually starts with the jet getting .01 to .02 slow. It then lowers the nose a little and the MACH starts to increase. Suddenly the jet says oh, my bad and then raises the nose a bit higher. It then gets about .1 slow and dumps the nose again. As you know, once you get slow and on that backside of the curve, takes for ever to catch up in the climb. I don't know much about turbo props besides looking at C130s low in the 20s beneath me while crossing the pond lol.

I was teaching a GIII initial class back in the day and a C-130 guy was like, hey, what's MACH change over. I was so confused and then another said, we don't fly that high lol. It totally made sense when I had a helicopter guy ask, what's transition altitude in a separate class😁.  

[Flyfaster_MTN002 412]

2 minutes ago, G550flyer said:

The DC10, GIII, GV and G550 become real pitch sensitive when we swap from indicated airspeed mode to MACH mode of the IAS/FLCH. Most jets will swap to MACH speeds around 28500 to 29500(MACH change over). One day I sat and watched how bad it would get and the DC10 got pretty bad. It usually starts with the jet getting .01 to .02 slow. It then lowers the nose a little and the MACH starts to increase. Suddenly the jet says oh, my bad and then raises the nose a bit higher. It then gets about .1 slow and dumps the nose again. As you know, once you get slow and on that backside of the curve, takes for ever to catch up in the climb. I don't know much about turbo props besides looking at C130s low in the 20s beneath me while crossing the pond lol.

I was teaching a GIII initial class back in the day and a C-130 guy was like, hey, what's MACH change over. I was so confused and then another said, we don't fly that high lol. It totally made sense when I had a helicopter guy ask, what's transition altitude in a separate class😁.  

The myriad differences can be nuanced even between TP's. E.g. the King Air's will over torque @ high DA's where we really don't. In the mountains they are limited to like 80% max torque (assuming not too hot out) to account for bloom on rollout. You likely aren't too concerned with torque and ITT #'s that can destroy your $1M engine. The temps and prop speeds really add to the drama. We don't do mach changeover either. It is pretty meaningless when max cruise is 320kts (ish) regardless. No step climbs needed however, unlike the barbie jets.

The C-130 is designed to do cool things down low and has many flap settings as a result. JATO takeoffs don't suck 🙂 Spent some time in a Challenger 300 in the FL's and that coffin corner gets interesting especially if you have to shut an engine down.

Hopefully we get some of those cool planes in MFSF eventually...

[Cpt_Piett 4,672]

1 hour ago, Flyfaster_MTN002 said:

You should be climbing on IAS or FLC. Descending on VS.

Care to elaborate?

[ark 1,291]

2 hours ago, Cpt_Piett said:

Care to elaborate?

My understanding has been IAS or FLC is usually preferred for climbs because it provides airspeed protection against an inadvertent stall in case something unexpected happens or you get distracted for some reason. Often VS is preferred for descents because if makes calculations easier when it comes to hitting altitude constraints, such as during a STAR. You usually know how much altitude you need to lose by the time you reach some waypoint, or the traffic pattern, etc. These are just general guidelines.

What I often find handy is the rule of thumb to start descending 3 x the number of feet you have to lose in 1000s NM out, and use a VS of 5 x your ground speed.  So if you have to lose 12000ft and your ground speed is 250 Kts, start about 3 x 12 = 36 NM out (it is good to add 10% to this) and use 5 x 250 =1250ft/min to approximate a 3 degree descent. It is interesting to watch a VNAV system work because you can often predict what it is going to do based on the above calculations -- kind of fun.

Al

As an aside, VS = 5 x GS is also a good starting point on a 3 deg approach.

Edited March 21 by ark

[G550flyer 1,014]

1 hour ago, Flyfaster_MTN002 said:

You likely aren't too concerned with torque and ITT #'s that can destroy your $1M engine

That would totally be my fear. I always wondered about the different power settings turbos have. Pistons scare me even more as you could be doing damage and not realizing it. I looked up SETP and that's a sweet ride for sure.

1 hour ago, Flyfaster_MTN002 said:

Hopefully we get some of those cool planes in MFSF eventually...

Yes! More cool planes and dangerous weather!

[Orlaam 306]

Never had a problem.  My regimen in to set elevator trim to the bottom of the green line (mostly upward), rudder in between neutral and the T/O position (T/O position for strong winds at the surface).  After take off, gear up, flaps up, YD on.  Pitch for about 140 knots, engage IAS, HDG or NAV, then AP on.  Inertial separator off when clear of icing conditions, 850 mode on anytime.  Remember that turning the inertial separator off increases torque, so have 850 mode on or decrease power well below the yellow line first.  Decrease RPM to 1900.  She will climb to ceiling without any issue at that IAS held speed.  The TBM850 from Black Square does have an issue where the sound will change and the power will drop, but it's a sim limitation with having that additional torque feature (850 mode).  The power decrease doesn't happen on every flight either.  Not sure what triggers it.  As speed increases at cruise, straighten out the rudder and keep the ball centered.  On approach/final you will need to move the rudder offset again for the slower speeds.

For descent, use standard V/S mode.  I use the GPS (GTN 750) as a guide for my required FPM. 

[Ron Lefebvre 112]

Yep, that's what I did last 2 nights; although closer to 160 knots to push the envelope a little and it went well.

with the throttle at more or less 80%, the fpm at around 1200 up to 20000 feet.

Just kept it at 80% and the pitch moved down to around 900fpm and kept climbing.

Did not touch anything until I levelled off

No loss off power on either trips.

Thank everybody for helping.