A couple of minor bugs worth pointing

[mizra108]

I tend to do turnarounds most often and during these turnarounds I’ve noticed a couple things, which hopefully can be addressed:

- FMC does not always recognize a landing and therefore FPLN Legs data and perf data does not erase, so essentially the fmc remains programmed. It has happened that it erases all the data automatically but it does not do so predictably and its rare. Is this realistic? 
- Once aircraft Is taking Off after the turnaround, the TO warning horn sounds throughout the takeoff roll even though aircraft is correctly configured (parking break off, trim in green band, flaps set, etc etc) and turns off as soon as wheels off the ground. This only happens on turnarounds, not on a initial leg.

 

- Another minor bug I’ve noticed, is that crew oxygen level starts at say 1600psi as read off the gauge in the ovhd panel, and once off the ground, it starts to depleet throught the flight, often reaching 800-900psi. As soon as I land, the gauge reads 1600psi again. 
 

- This is not a bug, but just an ibservation. Not sure if this aircraft is the same as the NG but if remember correctly, when you first add AC pwr to the aircraft from a cold n dark state, it could take the aircraft some minutes before the stick shaker warning test buttons would do anything (cant remember the reasons why) but ive noticed  that on this classic, it works instantaneously, is this accurate?

 

thanks!

[Litjan]

Hi mizra,

the FMC should erase the routing once the groundspeed is under 60 kts, iirc. If this doesn´t happen (I haven´t seen this not working), you can manually reset it by entering a new ORIGin in the RTE page.

I have heard of the takeoff config problem before and I believe it may be related to a variable with the spoilers not resetting all the way to 0. Another indication of this is that after a replay the spoilers always "pop up", even though I make sure that I stow them before I enter replay mode. It could also be due to an axis being assigned to the speedbrake and that axis not going back all the way to 0 - although I have relaxed the requirement for that a bit in one of the last patches. Two options: Test the takeoff config warning by quickly advancing the levers when you are on the taxi-out to the runway (the engines are slow to react, so there isn´t much danger to create too much jetblast). Another option is to simply click "reboot gizmo" when you are at the stand - this will reset all systems for sure.

The oxygen pressure depleting is due to "cold soak". The pressure goes down as the bottle cools off when climbing into cold air.

I really can´t answer the if the stall warning should work right away - I have never tried this in the real aircraft (push right away) - they are dependent on the "stall warning computer", which may need a bit to boot up. No idea how long, though, definitely not "a few minutes". They are certainly not dependent on the IRS units, I know for sure we tested them before those were fully aligned (in fact only a few seconds after turning those on).

Cheers, Jan

 

[mizra108]

Hi Litjan, thanks for your quick response and valuable insight!

With respect to the FMS resetting, I did notice that changing the origin resets the flight plan, I was just not sure why was it doing it automatically sometimes and other times it was not. I thought the logic for resetting the FMC used weight on wheels. Knowing that it depends on GS now, it begs the question: What if I have a RTO beyond 80kts, as the speed depletes below 60kts would the FMC reset everything then?

Another thing I want to point out which I just remembered, while on ground during turnaround, I create the new flt plan in simbrief and download the fms file so that i can simply type in the co-route in the CDU, but oddly, i get a message displayed in the the CDU stating that the route was not found (it is strange since the FMS file location of the downloaded flt plan is the same as that for the initial leg, which did not give me an error.

In regards to the TO warning horn going off, what you mention about the speedbreak is exactly the culprit,as it remember noticing one of the spoilers only just up slightly, which I found odd. Weird part is that my mapped lever work flawlessly so not sure why it did not go fully down after retraction after landing. I will test this to see if I can figure it out but appreciate the insight as this points me in the right direction.

Once again, thank you!

[Litjan]

Hmm, I would have to look up the logic for the FMS resetting - it could be that it needs to get airborne or past a certain speed first before the 60kts rule applies.

I am not at all familiar with SimBrief, but yeah, having the .fpl file in the correct location should work! I am not sure if maybe the algorithm only checks for .fpl files once when the plane initializes? Maybe try with the "gizmo reset" trick and see if it takes the (new) .fpl then? If so then we clearly have something we need to fix!

Whats interesting about the speedbrake is that on the real 737 those "end switches" sometimes were a bit "rusty" as well - so the first thing the Captain does when the horn goes off is slam the lever forward really good ;-)

Cheers, Jan