A list of Squawks as a 10+ year TBM Maintainer
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Hey everyone, I want to start this by saying that this is not a list of complaints just to complain, I want to offer my advice and experience in an effort to make this a better, more true to real life aircraft for everyone that enjoys BlackSquare's products. Admittedly, the TBM is all I own from BS as it fits the current void in the TBM sim space for me until the HotStart TBM900 is brought to XP12.
A little bit about me, I'm an aircraft maintenance technician based in the US, that works exclusively on TBMs, from the 700A up to the 980. I've got 11 years under my belt now of just working on TBMs. I've been on hundreds of maintenance test flights, and thousands of pre and post maintenance ground runs, years of factory training provided by Daher and while I'll be the first to admit if I don't know something, I'm well knowledgeable in all the systems of the TBM series.
I'd like to list discrepancies that I've noticed in my time flying the BS 850 Legacy and in an effort to not just list problems, I'll explain what I'd expect in the real aircraft.
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Air Conditioning/Bleed/Pressurization
- The deice boots do not inflate if the bleed switch is in the OFF/RST position.
I noticed this in the default 930 as well when MSFS 2020 released, the airframe deice system does operate off of the the engine bleed, its ported off the P3 line prior to the P3 SOV(Shut off Valve), into an air ejector pump which creates both the pressure to inflate the boots, and the vacuum to suck them back down. Hence, the bleed switch has no impact on the operation of the airframe deice, and they should be able to operate so long as the engine is running. Preferably at or above 80%NG. - The cabin will not heat unless the AIR COND switch is on. Whether that be fan only or on. The bleed/pressurization system and the VCCS are two completely independent systems. One is for heating and obviously pressurizing the cabin, and the other is for cooling. This is true throughout the entire family of TBMs. In the legacies and older TBMs, there is a slight margin of cooling provided by the incoming bleed air due to the combination of a heat exchanger and the ACM style cooling turbine, if you command high temp and the bleed is on, you're getting hot air out of those vents. The A/C fan in the fan only position would only be acting as a recirculation fan, it does not draw the hot air in, that flow comes naturally from the pressure/flow of the bleed air being pumped into the cabin.
- The cabin temp system is a bit aggressive. This is not something I can really back up with verifiable truths, but more just my experience in them. The TBM is really good at staying hot, mostly from the sun heating up the cabin. You mix that with the bleed air entering the cabin being pretty hot, its more of a fight to keep the cabin cool than it is to heat it up. Its wintertime right now, and I find myself having to turn the high bleed on for every flight just to keep the cabin around 70 degrees fahrenheiht. Typically up in cruise, even in winter, there is going to be a level of heat impacting the cabin from the sun, I feel like that influence may be missing and the heating requirement is being calculated just by the OAT. Its rare for me personally to turn off the air conditioning in flight cause I need some cool air passing by me.
- The deice boots do not inflate if the bleed switch is in the OFF/RST position.
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Engine Operation
- The engine is slow to spool on the starter.
Typically what I see from starter engagement to hitting that 13%NG mark is 8-12 seconds depending on the battery state. The battery in the BS tends to be 25VDC when I jump in, I'd expect about 10 seconds to hit that point, but I'm seeing 15 seconds or more. I do ground run training as one of my job tasks, and what I teach people is that 18 seconds is your go/nogo point for starting the engine, if you're not introducing fuel at that 18 second after engaging the starter, you're not going to make your starter duty limit of 30%NG by 30 seconds. So my normal start in this is already butting up on that 18 second mark. That 13% is a minimum to introduce fuel, a good operator would wait until NG stabilizes to introduce fuel, which in 850s would be 15%-17%. Once lightoff happens though, the acceleration, temps and all look really on point to me. - I actually just tested this right now and I see its a non-issue, this was going to be where I mentioned that the manual override cannot reduce engine power, it can only increase it. Something I saw and commented on in one of the promo videos on youtube. Nice
- Beta. Prop RPM should increase, not decrease while in the beta(taxi) range. Typical prop RPM on the ground at idle is 1200 when NG is at 70% where it should be. As you bring the power lever back into beta, the prop blade is becoming more fine, creeping towards 0 degrees of pitch, with the NG not changing, this would cause the RPM to increase. Typically about 1500-1600 before it starts getting into negative pitch and slows back down again until you get into reverse and the engine starts spooling back up due to fuel being added from the reverse rigging of the FCU.
- Aux Boost Pump in AUTO. There is no disengage pressure switch for the aux boost pump. On shutdown, or loss of the mechanical pump, there is a 10PSI (+/-2) switch that triggers the annunciator message and engages the boost pump. When the pressure increases, the annunciator light will turn off, but the boost pump will stay on. The only way to "re-engage" the auto mode in regards to the boost pump is to turn the aux bp switch to on then back to auto. Whats seen in the BS is on off on off on off as it breaks that fuel pressure switch.
- The engine is slow to spool on the starter.
Thats all for now I suppose. I'll have to take the time at some point to put it through the full ground run and test flight checks prescribed by Daher. But I'll save that for if BS wants to take the time to address any of this. If so, I'd be happy to share some means of contact info in private.
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