PFD went dark and other minor bug potential

[chock767]

Hi all,

I bought IXEG couple days ago and have been flying it extensively and thoroughly enjoy every minute of it. 
However, there is some weird stuff going on when I did my test flight earlier. 
First, I tried shutdown the left engine in flight. This results in an odd display of PFD as shown below. Despite repowered the fail engine main bus by APU doesn't solve the issue. 
In addition to the issue above, I found that the stab trim brake doesn't work. Move the control column in an opposite direction to trimming doesn't stop the trim. 
Lastly, I often received a duct overheat light despite the fact that the duct temp gauge displayed a value lower than 88C.
Looking forward to hear your comment.

Best regards 

[Litjan]

9 hours ago, chock767 said:

Hi all,

I bought IXEG couple days ago and have been flying it extensively and thoroughly enjoy every minute of it. 
However, there is some weird stuff going on when I did my test flight earlier. 
First, I tried shutdown the left engine in flight. This results in an odd display of PFD as shown below. Despite repowered the fail engine main bus by APU doesn't solve the issue. 
In addition to the issue above, I found that the stab trim brake doesn't work. Move the control column in an opposite direction to trimming doesn't stop the trim. 
Lastly, I often received a duct overheat light despite the fact that the duct temp gauge displayed a value lower than 88C.
Looking forward to hear your comment.
 

Hi Chock,

thanks for the comments and trying some of the "deeper stuff"...

1.) I am not sure what is going on with your display - it is in the "power saving monochrome mode", but it should go back to full colour after you power the lost bus again with the APU - or switch the air fan to alternate. I can not see your overhead panel in that shot, so it is hard for me to see what is going on...

2.) Correct, we did not model the stab trim brake. I will add it to the list - at the time I didn´t want to risk the developer in charge sending me an anthrax letter if I come up with YET another thing influencing the trim system. And I figured - oh well, no one will know about this and figure it out... I guess I was wrong .

3.) Are you running the air-conditioning system on AUTO or MANUAL mode? In AUTO it should avoid the duct overheat pretty well, note that the temp sensor takes the total temperature (pack supply PLUS return air from recirculation fan), so to really get a sense of the pack outlet temp you need to switch off the recirculation fan. AND then take into account that there is a bit of a sensing lag - the duct temperature sensor is not the same as the pack outlet temperature sensor (which will trip the pack).

The AUTO mode can have a tough time if the temperature in the cabin is VERY low - it will drive the pack valve to full hot in response and then get over the 88C before it can drive it back down. This will happen if you reboot in the air at high alts (the cabin temp gets set to ambient, so could well be -50 or so), or if you power up the plane after it was parked in Siberia over night... In this case I recommend going to MANUAL mode first, put the pack valves about mid-way and then wait for the temp to stabilize (recirc OFF). Then gradually edge to WARM until you supply +70C or so. After the cabin gets to +15, you can go back to AUTO.

Please keep testing our model and report all your findings. We are happy to take everything into account and tune where needed and warranted!

Thanks, Jan

 

[chock767]

Hi Jan, 

Thanks for a great reply. 
1. I tried connect an unpowered bus with an APU later at a lower altitude and the PFD seems to behave normally now. I must have exceeded the APU altitude limit earlier. But is the PFD suppose to go monochrome mode like this ? If the APU happened to be inop while the engine out is happening, this would make it more difficult to fly IFR.
2. Understood. Thank you for your consideration. 
3. I had the mix valve in manual mode since the supply duct temp change pretty slow and I never thought of sensing lag was introduce. But probably because of the lag maybe that explain why the pack trip earlier before duct temp reaches 88C and overheat the duct pipe route to the flight deck in process. 

Also, I would like to ask; 
1. The cabin rate of climb seems to oscillate at cruise altitude and the outflow valve position always at or near the full close position. 
2. Will you model the PMC switch in future ? 

Looking forward to your reply. Really appreciated for your attention to detail and sorry for nitpicking.

Best regards 

[Litjan]

Hi,

The PFD and EHSI will go monochrome when the cooling airflow (avionics supply and exhaust fans) gets too low. This happens when a generator bus is not powered. The monochrome mode will keep the display from overheating - this is the way it works in the real airplane. To cure this, you can switch the fans to "alternate"...

The cabin rate of climb should not oscillate - we had some problems with that before and it might "jitter" a bit, but should not oscillate. The outflow valve should be "almost closed" for normal cruise conditions.

I don´t think we will model the PMC switch, it would be pretty complicated to get right and it is not used in normal (or abnormal) operation. It would only be used in case of an EGT limited engine or if the PMC of the opposing engine fails.

No worries about nitpicking, I rather enjoy discussing features of the 737 at this level!

Cheers, Jan

 

[chock767]

Hi Jan, 

Thank you for your explanation. 

I understand your reason for rejecting the PMC button. I was hoping to see HMC unit come in action but it would be a can of worm I suppose. While I am on the subject of the engine, I would like to ask that Boeing 737 classic have an approach idle mode? I used the anti-ice earlier and notice that engine rpm remained the same. 

Regarding the cabin rate of climb issue. In my case, the cabin rate of climb was oscillated in cruise, as you can see in a picture below. It always oscillated in a positive rate of climb but strangely the differential pressure remain more or less the same. 

In addition, I notice that the anti-ice switch for both wing and engine stuck in transit if I move it while the engine is shutdown. 

Best regards 

Edited June 13, 2016 by chock767

[Litjan]

On 13.6.2016 at 3:35 PM, chock767 said:

Hi Jan, 

Thank you for your explanation. 

I understand your reason for rejecting the PMC button. I was hoping to see HMC unit come in action but it would be a can of worm I suppose. While I am on the subject of the engine, I would like to ask that Boeing 737 classic have an approach idle mode? I used the anti-ice earlier and notice that engine rpm remained the same. 

Regarding the cabin rate of climb issue. In my case, the cabin rate of climb was oscillated in cruise, as you can see in a picture below. It always oscillated in a positive rate of climb but strangely the differential pressure remain more or less the same. 

In addition, I notice that the anti-ice switch for both wing and engine stuck in transit if I move it while the engine is shutdown. 

Hi chock,

There is only HI IDLE and LOW IDLE on the 737 Classic. Hi idle is always active while in the air, and it varies with airspeed and altitude. Low idle is active on the ground (4 secs after touchdown, so you have better acceleration of the engine for reverse thrust).

Therefore you will not see any RPM change upon selection of anti-ice (like on the bad Airbus).

The anti-ice valves are "electrically controlled, but pneumatically operated" - so if you don´t have any pressure, they will not move anymore. So if the engine is shut down (not delivering pressure) the valves can´t move - but they "want to", so the "transit" (or disagreement) light is on if you move the switch.

Will look at the fluctuation again - it could be due to your low framerate - can you try and increase it (by reducing rendering options) to 30+ and see if the problem persists?

Thanks again for the input, Jan

 

 

[chock767]

Hi Jan, 

Thanks for the answer for the idle mode.

I forgot to tell you that I had the APU pressurized the duct and WAI valve is still in transit. Also with engines running on ground, WAI valve still in transit. 

Regarding the issue with fps and pressurization system. It is hard for my laptop to push above 30 fps and 25 fps is their best average. However, I tried using the stby mode and the cabin rate of climb is much more stable than auto mode. 
 

Best regards 

[Litjan]

1 hour ago, chock767 said:

Hi Jan, 

Thanks for the answer for the idle mode.

I forgot to tell you that I had the APU pressurized the duct and WAI valve is still in transit. Also with engines running on ground, WAI valve still in transit. 

Regarding the issue with fps and pressurization system. It is hard for my laptop to push above 30 fps and 25 fps is their best average. However, I tried using the stby mode and the cabin rate of climb is much more stable than auto mode. 
 

Best regards 

Hi and thanks for the feedback - I will try to reproduce the fluctuation with lower FPS. We had some problems with that one initially, and maybe we can tweak some more...

The Wing-Anti-Ice won´t open on the ground - so you will just see the "bright blue" until you lift off (unless you utilize the ground-test function, but that will only work for a few seconds, then the thermal protection will close it again).

Also note that you are not allowed to use the APU for wing-anti-icing - it is placing too much stress on the APU. However, it should operate the valve, I will look into that.

Can you send me another screenshot of the valve failing to operate during flight when pressurized by the APU?

Thanks, Jan

 

 

[chock767]

Hi Jan, 

Thanks for the reply. 
I am just realised, that not all 737 are capable of enabled WAI on ground. 
APU and WAI valve do operate perfectly in-flight. I was referring to APU when the aircraft is on the ground. 
I would like to apologize for my blunder. 

Best regards 

[Litjan]

1 hour ago, chock767 said:

Hi Jan, 

Thanks for the reply. 
I am just realised, that not all 737 are capable of enabled WAI on ground. 
APU and WAI valve do operate perfectly in-flight. I was referring to APU when the aircraft is on the ground. 
I would like to apologize for my blunder. 

Best regards 

No need to apologize at all! This stuff is incredibly complicated and I often refer to my manuals and real pics and vids when trying to figure out how stuff is supposed to work ;-)

Cheers, Jan