Nose over and straight into ground after disconnecting autopilot

[Gregg Seipp]

I've done about 100 flights in the TBM.  This was my second on 1.1.12.  I was on a short, relaxing morning flight on VATSIM, from KCLT, coming in for the ILS into KSAV, on dogleg to final.  Was just getting ready to put down the first notch of flaps, power was about 30 Torque, 190 KIAS.  All seemed pretty normal.  I'd set 2000 ft in the Alt window and VSed down about 1300 fpm.  When I looked up it had flown through 2000 and was down at 1600.  I disconnected the autopilot and, at that point,  the airplane immediately nosed hard over.  I pulled back on my yoke all the way and it only slightly helped.  It dove straight into the ground and crashed.  I've never, ever had this happen in X-Plane before.  Any thoughts as to why this would happen?  Logs attached.

EDIT:  I'm using X-Plane 11.41.

Gregg

Log-crash.txt

TBM900_Log-crash.txt

log_200405_125833_KCLT.csv

Edited April 6, 2020 by Gregg Seipp

[Goran_M]

It looks like your trims failed.  (Unless something happened to your calibration, which is unlikely.)

Did you check your maintenance manager pre-flight?  It's entirely possible the trim system was in a worn state, and the autopilot finally wore it down to an unrecoverable state.

 

[Gregg Seipp]

55 minutes ago, Goran_M said:

It looks like your trims failed.  (Unless something happened to your calibration, which is unlikely.)

Did you check your maintenance manager pre-flight?  It's entirely possible the trim system was in a worn state, and the autopilot finally wore it down to an unrecoverable state.

 

I did check maintenance before the flight and it was clean.  The flight was only an hour long.  Lord, a trim failure in flight can do that??  I pulled my yoke to the stops and got almost nothing.  I'd have thought you could manually override even if it was difficult.

EDIT:  Also, wouldn't it have said something about a trim failure in the log?

Edited April 6, 2020 by Gregg Seipp

[Goran_M]

I've seen it before.  Unless the autopilot is on, If the trims fail, they will force the nose down.  I'm not saying for certain this is what happened, but it certainly looks that way.  

[Gregg Seipp]

3 minutes ago, Goran_M said:

I've seen it before.  Unless the autopilot is on, If the trims fail, they will force the nose down.  I'm not saying for certain this is what happened, but it certainly looks that way.  

Well, the obvious question is...what do you do?  I mean, you don't see airplanes flying out of the sky so there must be something...?

[Goran_M]

Good question.  The cases I've seen are because the aircraft did a tail strike the flight before, and it damaged the trim linkages without the person knowing.  So the next time they took it up, it was a catastrophic failure.  I can't say I've seen everything in good working order, suddenly failing, which is why your situation appears to be a unique one, unless the trims got damaged on some kind of bad terrain tile in the scenery you were in.  This has also happened before.  Just make sure that when you load the first time, the aircraft doesn't "drop" onto the scenery ( a sign of bad terrain) and you don't pop any wheelies.  It's definitely not a common occurrence. 

[Gregg Seipp]

1 minute ago, Goran_M said:

Good question.  The cases I've seen are because the aircraft did a tail strike the flight before, and it damaged the trim linkages without the person knowing.  So the next time they took it up, it was a catastrophic failure.  I can't say I've seen everything in good working order, suddenly failing, which is why your situation appears to be a unique one, unless the trims got damaged on some kind of bad terrain tile in the scenery you were in.  This has also happened before.  Just make sure that when you load the first time, the aircraft doesn't "drop" onto the scenery ( a sign of bad terrain) and you don't pop any wheelies.  It's definitely not a common occurrence. 

Ok.  No, there was no 'drop in' this time though I have seen from light 'drop in's from time to time but I did check the maintenance.  The departure was very ordinary and I hand flew it up to about 10,000 without a problem.  No turbulence either.  So, the only solution is to let it crash??

[Goran_M]

Perhaps ask toto in the discord what his thoughts on it are.  I can safely say it's not something that is fixable in flight, but I'm guessing there must be some way to avoid it.

[Gregg Seipp]

17 hours ago, Goran_M said:

Perhaps ask toto in the discord what his thoughts on it are.  I can safely say it's not something that is fixable in flight, but I'm guessing there must be some way to avoid it.

I have.  Not a peep so far.  I'm seriously hoping there's something...another option other than crashing.

Gregg

[Hangar]

Gregg maybe try putting the a/p back on if it ever happens again, if you're high enough maybe it'll be able to save you, heh.

[Gregg Seipp]

7 hours ago, Hangar said:

Gregg maybe try putting the a/p back on if it ever happens again, if you're high enough maybe it'll be able to save you, heh.

Yeah, good point and that thought crossed my mind as did some others, though, I can't remember if I thought about it before or after the crash.  It happened very fast and, to be honest, I was caught by this fairly flat-footed.  Here's what I have thought about after the fact:

• Should have pulled power immediately (common sense).  Would the airplane have continued to upside down if I'd have done that?  I might have been able to roll out of it with aileron and turned the autopilot back on.  (Though, it begs the question, what next?  How do you land a TBM on autopilot with a broken trim system?  ILS, zero flaps to keep the nose up, and land at the lowest speed possible using a bit of power to slow descent before touchdown?  At best, a controlled crash.)
• I should have done a replay and looked at the state of the trims and other things before it happened.  (e.g. it's a kind of flight recorder.)  I could have also recorded the playback.  
• Why would an airplane be built to commit suicide and kill its passengers?  This is the opposite of what airplane manufacturers do.  
• If it was the trim system, why couldn't I override the dive with control input?  A trim system is only so strong.  A TBM is not a Cessna but I did have to demonstrate that I could override the trim system in Cessnas when I got my PPL.  I even had to do it on the day of my exam.  It takes some strength but it can be done.  From that perspective, it seems just as likely...perhaps more likely...that the elevator control wire snapped.  There was nothing I could see in the log which said what had failed.
• Was the fact that I had to click the VS button twice in any way related to what happened?  
• Very unlikely that it was an icing thing.  I was on top of that on decent through clouds, no precip, and the weather was warm when I got low.
• It wasn't a weight and balance thing since the airplane flew fine on autopilot.  A WB problem would have been just as bad under autopilot.

 

[awillimd]

On 4/5/2020 at 5:40 PM, Gregg Seipp said:

I've done about 100 flights in the TBM.  This was my second on 1.1.12.  I was on a short, relaxing morning flight on VATSIM, from KCLT, coming in for the ILS into KSAV, on dogleg to final.  Was just getting ready to put down the first notch of flaps, power was about 30 Torque, 190 KIAS.  All seemed pretty normal.  I'd set 2000 ft in the Alt window and VSed down about 1300 fpm.  When I looked up it had flown through 2000 and was down at 1600.  I disconnected the autopilot and, at that point,  the airplane immediately nosed hard over.  I pulled back on my yoke all the way and it only slightly helped.  It dove straight into the ground and crashed.  I've never, ever had this happen in X-Plane before.  Any thoughts as to why this would happen?  Logs attached.

EDIT:  I'm using X-Plane 11.41.

Gregg

Log-crash.txt

TBM900_Log-crash.txt

log_200405_125833_KCLT.csv

This has happened to me twice now too. Monitoring and will provide log if it happens again.

[JamesD]

Same thing happens to me. Total loss of control after auto pilot disconnect.

[Goran_M]

1 hour ago, JamesD said:

Same thing happens to me. Total loss of control after auto pilot disconnect.

Check maintenance manager for broken trim linkages

[CJSouthern]

I've had this happen to me too; not sure if this is related of not but I started with a REALLY "hairy" takeoff (I think my trims weren't set) and I "saved" it by engaging the AP. Control was nominal through 10,000 feet. When I disconnected the AP at TOD to hand-fly it down the other side all hell broke loose similar to the above posts. I tried to re-engage the AP but it wouldn't re-engage.

 

[Goran_M]

If trim linkages are not damaged, check for ANY assignments that could be interfering with your autopilot or trim.

There is no known issue to this, and seems to be isolated to a few cases.  

[mbaclawski]

I Had the same problem coming off A/P  using both my trim wheel and Saitek A/P board. After awhile I gave up even using the A/P, the fix was

A trim wheel .Lua that centers the trim so it doesn't  reset back to it's last known setting , will have to see if I can find it I haven't had any problems since. 

The TBM is by far the Best A/C created   Period !!!!!!    I wasted a Ton of money on other Platforms and Aircraft.   1 sim 1 Plane  now so Thank you  Hot Start !!

 

[SPE720]

This just happened to me as well for the first time!! Disconnect and straight down. On another note my V/S indicator was also not functioning. I hadn't seen that before either.

[Goran_M]

One of the reasons lua scripts can be a blessing and a curse.