Random Shutdowns on Departure/Landing

[dizzle70]

Hi,

I have had issues with the Saab experiencing random shutdowns on takeoff and landing.

When I turn onto the runway, and I pull full power and then receive a config (I was told it was T/M conditions levers that were causing it), I would reduce the power back down and it would shut down. I landed at an airport just recently and pulled the aircraft into full reverses, then back through normal and to power up to taxi before it just randomly shut down on the runway and I had to restart the aircraft.

Logs/Giz Logs are attached.

 

Cheers

GizmoLog.txt

Log.txt

[JGregory]

Is this happening on EVERY flight? 

 

We have had a couple of reports of the aircraft shuttling down (randomly), usually right after landing.  There are some other forum posts here where this is discussed.  My best guess at this point is that it was due to overly aggressive movement of the power levers.  

 

You stated " ... and I pull full power..".  You should not be pushing the power levers to their maximum at takeoff.  This will overheat the engine and "could" cause a shutdown.

 

I noted that you are using some hardware and also have AI aircraft enabled.  If you want to help diagnose this issue, you could do the following:

1. Disconnect ALL hardware.

2. Disable all AI aircraft.

3. Disable any third party plugins (except Gizmo).

3. Reload the sim.

4. Fly the Saab and report back if you have the same issues.

 

I would also be interested to know what your frame rates are.

[dizzle70]

13 hours ago, JGregory said:

4. Fly the Saab and report back if you have the same issues.

I would also be interested to know what your frame rates are.

Did all those steps, I went to land and idled the power and as soon as I touched down the plane went full reverse (i'm guessing idle of the joystick is full reverse and i'm not sure how to fix that) and it shutdown again on the rollout (did not increase the power, shut down with reversers).

Frame wise - we tweaked some of the settings last night as I had no landing lights so we are now at High (HDR) and 2x SSAA+FXAA and I'm getting roughly 22-30FPS for most of the flight.

Cheers

[JGregory]

10 hours ago, dizzle70 said:

I went to land and idled the power and as soon as I touched down the plane went full reverse (i'm guessing idle of the joystick is full reverse and i'm not sure how to fix that) and it shutdown again on the rollout (did not increase the power, shut down with reversers).

Wait... if you disconnected the hardware (as I suggested in step 1, and you confirmed stating "Did all those steps"), how can you be using your joystick ???  

Also, what do you have your joystick(s) mapped to?

 

Edited August 26, 2018 by JGregory

[nomdeplume]

23 hours ago, dizzle70 said:

Did all those steps, I went to land and idled the power and as soon as I touched down the plane went full reverse (i'm guessing idle of the joystick is full reverse and i'm not sure how to fix that) and it shutdown again on the rollout (did not increase the power, shut down with reversers).

That would probably be it, the Saab model does not use a separate range for reverse like some other aircraft, so you have to be careful how much you pull the power back. Keep an eye on the virtual throttle in the 3D cockpit and only pull your physical throttle back to where it 'snaps' to the flight idle position when you're landing. You can also use the popup to keep this on screen at all times.

After touchdown, gently pull it back further to go into beta and engage the reverses. If you do it too quickly (especially if you're landing fast) it'll overload the engines and they'll shut down.

The same applies when powering up for take-off as well; it does not respond well to sudden throttle changes. You can easily redline the engines if you don't ramp up the throttle gradually.

[Tassierob]

On 8/27/2018 at 2:27 PM, nomdeplume said:

That would probably be it, the Saab model does not use a separate range for reverse like some other aircraft, so you have to be careful how much you pull the power back. Keep an eye on the virtual throttle in the 3D cockpit and only pull your physical throttle back to where it 'snaps' to the flight idle position when you're landing. You can also use the popup to keep this on screen at all times.

After touchdown, gently pull it back further to go into beta and engage the reverses. If you do it too quickly (especially if you're landing fast) it'll overload the engines and they'll shut down.

The same applies when powering up for take-off as well; it does not respond well to sudden throttle changes. You can easily redline the engines if you don't ramp up the throttle gradually.

Yep I can confirm full reverse is a killer. I accidentally went to full reverse landing yesterday with my Saitek throttles and ended up sitting on the ground in the dark with 2 dead engines! The tower was not impressed LOL. 

[jumpjet]

Yeah it happened to me about 30 mins ago when landing at Kabul. At an elevation of 5,877 feet, almost fully loaded, full power, full props, and full flaps, I could only just maintain 115kts.

I was so happy to get down,, that I forgot about the sensitivity of this aircraft, and pull back too quickly on landing. The aircraft just conked out as I reached a taxiway. :-)

The throttle and conditioning levers will take some getting used to. Getting the aircraft to take off power without overcooking it can be a challenge too. The most of the throttle action seems to come in the final third of travel, I would love to see it more evenly spread (from ground idle upwards) throughout the travel range of the lever.

I am not so sure that I should be taking this aircraft up to Nepal and Kathmandu as I tour this area of the world (I'll have to check the limitations)  ;-)

Edited August 31, 2018 by jumpjet

[Tassierob]

3 hours ago, jumpjet said:

Yeah it happened to me about 30 mins ago when landing at Kabul. At an elevation of 5,877 feet, almost fully loaded, full power, full props, and full flaps, I could only just maintain 115kts.

The throttle and conditioning levers will take some getting used to. Getting the aircraft to take off power without overcooking it can be a challenge too. The most of the throttle action seems to come in the final third of travel, I would love to see it more evenly spread (from ground idle upwards) throughout the travel range of the lever.

I am not so sure that I should be taking this aircraft up to Nepal and Kathmandu as I tour this area of the world (I'll have to check the limitations)  ;-)

Make sure you set the CTOT correctly for take off and stop advancing the throttles as soon as it takes over. Operating from high altitude will be a big part of your problem however as it restricts your power on takeoff lots.

P127 and 128 of the flight manual describe CTOT in detail.   I note the normal max climb position with CTOT off and move the throttles no further forward than that after TO,  turn CTOT down then disengage it when Torque is about right.

The condition levers should only ever go to the max position, no further forward.

As to the travel on the throttles unless you have a full sized one with the same travel there are always going to be compromises with the amount of travel relative to the real aircraft. Personally I find reverse the biggest issue. I use 2 Saitek throttle quadrants.

Landing...I have read on a SAAB pilots forum that unless the runway is really short then a lot of SAAB drivers only use flaps 20 as it gives better go around performance. Also only flaps 20 in a crosswind. Thats the way I fly most of my arrivals now.

Hope that helps a bit!

[jumpjet]

8 hours ago, Tassierob said:

Make sure you set the CTOT correctly for take off and stop advancing the throttles as soon as it takes over. Operating from high altitude will be a big part of your problem however as it restricts your power on takeoff lots.

P127 and 128 of the flight manual describe CTOT in detail.   I note the normal max climb position with CTOT off and move the throttles no further forward than that after TO,  turn CTOT down then disengage it when Torque is about right.

The condition levers should only ever go to the max position, no further forward.

As to the travel on the throttles unless you have a full sized one with the same travel there are always going to be compromises with the amount of travel relative to the real aircraft. Personally I find reverse the biggest issue. I use 2 Saitek throttle quadrants.

Landing...I have read on a SAAB pilots forum that unless the runway is really short then a lot of SAAB drivers only use flaps 20 as it gives better go around performance. Also only flaps 20 in a crosswind. Thats the way I fly most of my arrivals now.

Hope that helps a bit!

Thank you for that.

I happened to read that section of the manual last night in bed. Indeed I embarrassingly was on reduced power and hadn't set the CTOT knob, which also explains the challenging shallow take-off I had leaving Dushanbe (2574' elevation) ........ doh!

What's that expression? ....... errrr ...... RTFM!

Edit: I tried liking your post, but I am having trouble in both firefox and chrome (chrome worked yesterday) I think it's a mixed content https problem, that I can't seem to fix (yet)

Edited September 1, 2018 by jumpjet
added edit