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FG Shuttle: Electrical Failure in Deep and TAL

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FG Shuttle: Electrical Failure in Deep and TAL

Postby GinGin » Sun Sep 23, 2018 12:09 pm

Good Morning,

A (quick) sum up of my last journey in Space.
I am working on failure with some real Non Normal Checks, which is quite interesting for me. Problem with the Shuttle, it is the ton of documents available depending of the stage of the mission.
And documentations are divided between Commander, Pilot and Mission Specialist ( which usually have all the actions to check if everything is done from behind)

So for this flight, I took it easy with a "simple" electric failure during Stage 2

A quick Look on the different documentations available for dealing with Non Normal Stuff

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Different docs for different phases.

From Lift off and until MM 104 : AESP ( Ascent/Entry Systems Procedures https://www.nasa.gov/centers/johnson/pdf/359893main_AESP_G_O_4_P%26I.pdf )

From Meco until OMS 2 ( MM106), APCL ( Ascent Pocket Check List https://www.nasa.gov/centers/johnson/pdf/366508main_APCL_G_O_1.pdf )


On Orbit, OPCL ( Orbit Pocket Check List https://www.nasa.gov/centers/johnson/pdf/359853main_OPCL_G_M_10.pdf)

During Entry Prep, EPCL ( Entry Pocket Check List https://www.nasa.gov/centers/johnson/pdf/366509main_EPCL_G_M_11.pdf )

And at beginning of Entry Interface MM 304 mode, AESP ( same than during Liftoff )




200 pages in each book, but there are similar part and duplicata for every crew ( Commander, Pilot, MS)
So, it's more like 40 or 50 pages to deal with a huge variety of failure

Why different Checklist? Well because during Liftoff and Entry, there is no time for long checks, so in the AESP, just the vital actions are listed ( to be done under 5 mn after the failure)

In the others checks, there is more time to go deeper into the problem and troubleshoot it in a safer way for the rest of the mission.

An example, during ascent for electric failure, aim is to quickly identify the faulty bus or cell, and cut it off. Then once in orbit, systems can be reorganized to be re energized again by good buses, etc





Let's start our lovely flight.

A day before the launch, excellent conditions with a warm and wet morning in Florida

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Next Morning, time of Launch, cloudy but still fair weather for a launch

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Last external Shuttle insepction, LOX and LH2 are being vented well while kept under High pressure

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Lift Off on time, tower cleared and Roll programm

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Actively monitoring is not an easy task with the Booster shaking our head with 3 G's


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Already high and fast after a minute into the air, that's a Spacecraft

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Booster separation, Stage 1 is over.

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Master Caution and Alarm, several red and yellow buttons are flashing on the Caution and Warning central display, Oups :)

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First thing is to prioritize the failure to start with the most urgent
Left Engine Failure on one side and Main Bus Undervolt, AC voltage, FC Stack Temp and AV Bay/Cabin FAN on the other with some black screens

It might be linked or not ( Here it is independant failures, engine on one side, electrical on the other)




Relative Velocity of 7500 fps, it's gonna be a TAL abort to Istres
TAL and Abort selected, followed by OMS Dump

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Now, let's go deeper in the electrical failure
Here again, we can suspect a Bus Shortage somewhere. 2 screens shedded only, first guess of just one electrical system involved there

Let's start with the highest priority alarm, the fuel stack Temperature. It means that one of the Fuel Cell is not cooled anymore and Temperature is rising which can lead to an explosion, hence the priority there




Checklist here

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And Electrical parameters available from the System Management Major Function coming from the BFS


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Stack temp at 274 °F and Amps above 360 ( 1636), massive shortage there, probably on the Main Bus A
As directed, we have to go to the Main Bus Undervolts/FC Checklist and directly to the step 4


That one


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We have to close the Ess Bus and FC/Main bus associated ( Fuel Cell 1 and Main Bus A as guessed)


Let's do that there

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Results


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Fuel Cell voltage back to a more normal Value, no more power in Main A and ESS 1BC. No controller linked to Bus A and no more AC power from FC 1 ( hence the AC low voltage caution associated)
Also, stack Temp is now stabilized around 280 ° and no more Amps and shortage.


Step 8 of the check, we see that with more than 32 volts in the FC ( 32.5 there), we have to go to the Bus Loss Action Checks
Normally , this one is for after MECO ( reorganisation of the systems linked to the Main A and AC1)
It is in the APCL.
But we have time there, I will go through it now


MNA ( entire Bus) It is the good one, we lost all the bus A. So we will have several things to reconfigure

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Basically, reconfiguration here will impact Avionics Fan Bay 1 and 3 to switch to AC 3 and AC 2 ( hence the AV bay caution, no more air cooling into those bay, so temperature was rising. )
Also, one Loop of Freon is inop ( loop 1), to be switched to AC2, and some reorganisation on Flash Evap heaters


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Some checks that the Fan are working and temps in Bay 1 and 3 decrease

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All good there


Everything under control, but Stack Temp is still at 280 °
Let's go back to the Fuel Cell Stack T Check

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Step 7, if stack Temp not decrease, we have to stop the FC.
Let's do that then

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Final Check on the SM summary

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Av Bay and Fuel Cell stack temp caution dissappeared.
The 3 others are associated with the shortage and have been treated

No more power on the Fuel Cell 1 and Bus A . No Amps and Temperature at 48 ° now. Case closed.
We could have Tied the Bus A with the 2 good remaining Cells, but it is not advised to do so in case of Shortage to not short the other good buses.

So we will stay like that, with still 2 good cells remaining.
But another problems in a cell could lead to more severe stuff, like shut down of one APU or Engine Lock up.




Back to our TAL situation now :)


Roll to Heads Up, reaching 14000 ft/s

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After MECO and OPS 3 transition, ready for the entry

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Catching the path from above and Burning Hard, but within limits

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What a complex Beast, I am like a good when I see all those buttons and systems working perfectly together

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APU check, running normally

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All filters implemented, State vector is kept under good control

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South French Coast in sight

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Entering the HAC at 30000 feet

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Diving into the layer, 12000 feet and 6 Nm from Touchdown, all good

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Welcome Back folks, another good stories for your kids there :)

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Very fun scenario, and what a nice modelisation of systems. I mean, being able to deal with non normal stuff in a game using NASA checklist at 80 % is quite awsome.


Just a quick test on Cross Tie with shortage

Here I tied Main A and Main B
Shortage led to a short in Main B and loss of an APU


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And there Main A with Main C
It led to even more black screens, meaning that Main C is short and we loss another Buss by cross tiying ( we would have lost an engine in orbit)

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So indeed, never Cross Tie a short Bus :)
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Re: FG Shuttle: Electrical Failure in Deep and TAL

Postby it0uchpods » Sun Sep 23, 2018 1:11 pm

Awesome! The shuttle is amazing! I'm (slowly) learning it, so I can partake in these fun adventures.

Kind Regards,
Josh
it0uchpods/WTF411

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Re: FG Shuttle: Electrical Failure in Deep and TAL

Postby Thorsten » Sun Sep 23, 2018 4:16 pm

Admittedly I have no clue what the code for the fuel cell stack temperature actually does... :mrgreen:
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Re: FG Shuttle: Electrical Failure in Deep and TAL

Postby GinGin » Sun Sep 23, 2018 5:21 pm

Ahah, thanks Josh. No doubt you will master it quick enough

@Thorsten : Ahah xD Well, it works quite well. According to the checklist, I am always in one or an other case, and troubleshoot can be done.
I tried massive failure by clicking 3 or 4 times on the failure panel ahah what a mess and intrication between systems

Would it be possible to add other failure in system failures panel? Like Freon or OMS or stuff like that
Plenty of nice checklist for that :)
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Re: FG Shuttle: Electrical Failure in Deep and TAL

Postby Thorsten » Sun Sep 23, 2018 5:35 pm

Sure, but you know you can just program them (probabilistically) into the mission file? Or trigger the property nodes using the property browser?
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Re: FG Shuttle: Electrical Failure in Deep and TAL

Postby GinGin » Sun Sep 23, 2018 5:42 pm

Ah yes true. I will try that so. Failure SHortcut is quite handy. It s like being an instructor in a sim :)
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