Low aft fuel - roll to the left side?
-
I’m not sure if BMS models fuel weight exactly but if it did, you’d get the imbalance much earlier and you’d be getting it gradually?? Didn’t you look at your needles to check for imbalance?
-
Maybe you should look for an answer in the flight model, the imbalance shifts the CG laterally and longitudinally and the flight control system might try to compensate. Lowering the gear changes the FLCS gains so you get a difference response.
-
it’s not a bad thing to do in the SIM when you are under 500 or less on final is to just turn your APU on, you do not want everything to go dead, 50 feet above the runway.
You also don’t want the ground crew dead 50 feet away from the jet
The EPU in the F-16 isn’t like the APU on other aircraft types, it is an emergency system meant to continue to provide electrical power in the event of engine failure. It is unique in that it uses hydrazine as a fuel source (nasty nasty stuff) which is highly toxic, so anytime the EPU is activated it requires special handling and procedures, so you do not activate it as a matter of course in the Viper, leave it off unless directed by the emergency checklist.
-
Any ideas about the details of this “special handling and procedures”???
-
Any ideas about the details of this “special handling and procedures”???
Yeah sure, mostly deals with quarantine of the jet with the activated EPU until they can shut it down and ensure no vapors are reaching emergency personnel and ground crews. We basically are using the real world SOP:
8.2.7.11. (Added-8VFW) Hydrazine Procedures.
8.2.7.11.1. (Added-8VFW) Hydrazine parking areas are at the north and south EOR
(Attachment 8 and 8WP IFG).
8.2.7.11.2. (Added-8VFW) Local Hydrazine Recovery.
8.2.7.11.2.1. (Added-8VFW) When recovering at Kunsan AB, taxi the aircraft to the hydrazine response area and park with the left wing into the wind.
8.2.7.11.2.2. (Added-8VFW) Wait five minutes for the hydrazine response teamto check the aircraft. The aircraft may be shut down after the hydrazine team completes their checks.
8.2.7.11.2.3. (Added-8VFW) Prior to shut down ensure the EPU is OFF and the aircraft is pinned, de-armed and chocked. Wait until assisted out of the aircraft by the fire/rescue crew.If you want to learn even more there is a whole book called, “F-16 Hydrazine Procedures” written by the 482nd FW, this is a local procedure, but would be based off the USAF AFI here which is where we most likely developed our local SOP from
-
Thanks for your contributions!
Unfortunately no explaination why the jet would shift to the left when the left wing is empty! Also, no explanation what caused the levelling out (aside the note that lowering the gear changes FLCS behaviour).
I set BINGO, I got the warning, I just ignored it, as I thought I could make it home. No doubt, that this was a bad decision! But everybody could get into the same situation caused by “anything” happening during flight.
I was too much suprised when the shift occured that I did not check the imbalance indicators (I’m a bloody beginner). Still, if I had checked the indicators I wouldn’t have known what to do to correct it.
In T.O. BMS1F-16CM-1 there is a small paragraph in the fuel section about roll shift, but this refers to imbalance after takeoff and only a slight imbalance that you should just trim out. That’s fighting the symptoms, not the cause!
There is a lot of information as how everything works but not as what actually to do!
I’m looking for something like this:
If the jet shifts to the side (left/right) due to low fuel (AFT/FOR) then do the following:
1. ….
2. …
3. …An emergency procedure for imbalances caused by low fuel.
-
Well, i guess more information are needed, the situation you give us is confused and you may have missed some stuff.
- did you get a trapped fuel hud warning
- was your fuel pump knob really to NORM?
-did you had fuel tanks, where they empty? - was your fuel qty sel switch to norm?
- what was your bingo setting
- what were the needle aft and forward and totalizer saying?
you can’t expect an emergency checklists if you ignore all the prior warnings. You must act on the first warning (in this case the bingo message) if you don’t you screw up and the only item of your next emergency checklists is eject eject eject.
from the few information you gave away i’m not convinced your situation was a fuel issue
You reported a wing shift after firing a harm, more than usual. That’s unverifiable, it’s a feeling. you might be right, you might be wrong. the only way to tell is by knowing the aft and forward needle of the fuel system to assess an imbalance or not.if it was fuel related, then i guess you had a trapped fuel condition, which in 99% of the cases is pilot error with a switch or a knob out of position.
that one is nasty and could lead to serious issues.your bingo ignore was the first error that lead to your crash.
the second was to fail to identify the issue with the fuel
the third was the lack of planning to go Simulated flameout for landing. you said you crashed 1/4nm from the runway, knowing your fuel condition below minimum, or even emergency fuel you should come in not for a straight approach (or certainly not an overhead but come in into the flamout pattern, that way, even if your engine quits then you have a lot of energy for a deadstick landing.As for the EPU, turning it ON is not necessary as said in the topic above, the EPU turns ON automatically (provided it coirrectly placed into AUTO) whenever the engine fails. from there it runs on air if RPM stays hi enough (which is not fully implemented in BMS unfortunately, we loose RPM windmilling too fast) and will consume hydrazine if air is nor enough (read rpm drops) so from there you have 15min of hydrazine fuel. more thanenough if you’re in the SFO pattern
-
Thanks for your reply!
To your questions:
1. No trapped fuel warning
2. Fuel Pump was definitely to NORM
3. No fuel tanks
4. QTY SEL switch was definitely to NORM
5. Bingo was 1.500
6. Unfortunately I didn’t check that (as I had to deal with that shift, looking for the runway, preparing for landing etc.)I KNOW THAT IT WAS ALL MY FAULT! The planning was basically OK, but I should have avoided my last bomb run when the bingo warning came up. As I said, my fault, but you may get into the same troubles when something goes wrong (not as planned) during flight, so I think it’s absolutely OK to ask for a solution scenario just in case. I thought I could make it to the runway before the flame out, so I did not prepare for that. I have read about this procedure and will learn it. But with that strong shift, a flameout landing would not have been possible at all.
The shift was MUCH STRONGER (VERY MUCH STRONGER) than the usual shift. It was tremendous, not just a vague feeling. I do not exklude the possibility that it was a joystick failure.
Thanks for the information about EPU (basically what the manual says).
When (in what scenarios) would I change the ENG FEED setting? Was it correct that I set it to FOR when AFT empty?
-
So let me recap;
you have a bingo warning so your fuel state is 1.5
if that’s you’re real fuel state (you can have false bingo warning if your fuel qty sel is not in norm - hence my prior question) then you CANNOT have a left right shift because of a fuel imbalance, unless you had a trapped fuel situation, which you ruled out!Therefore, based on your assumptions of what happened, your situation is not a fuel issue, it’s a weapon drop that caused the shift.
beside having the shift at the exact moment you fired the weapon would call a huge coincidence that the fuel imbalance manifested itself at the exact same moment
wings have 550lb each of fuel. you reported no wing tanks, so you can’t have the +2500 lbs hence 3000Lbs max on one side and not on the other for a potential imbalance
at fuel state 1.5 you’re on fuselage fuel only with all switches in norm (about 6.0) and the shift can only be forward-backward.
point proven - with the info you gave and the answers you gave.so remains to explain why you felt the drop significantly worse than usual
you mentionned no wing tanks? What was then loaded at the wing tank station? By chance did you had 4 harms and fired 2 at the same time - from the same wing?
that’s the one out of two reasons i could offer you
the next one is what about your roll trim knob position or even your rudder trim position? if they are out of centred, that may also explain the problem, but then it would have been noticeable before weapon drop as well, but probably not to the same extentif none of the above, well i have to admit i don’t know with the data i have at my disposal. I have my idea but i think you wouldnt like it
When (in what scenarios) would I change the ENG FEED setting? Was it correct that I set it to FOR when AFT empty?
in the current scenario, and the proposed justification based on your data, changing the engine feed is pointless since it can’t be a fuel issue
therefore to answer your question, you change the engine feed when you are sure you have an imbalance not because you feel it (it’s already too late) but because you made an ops check and the needle red portion indicates an imbalance
you correct that imbalance by adjusting the engine feed to forward or aft depending in which side you have the imbalance until the red portion of the needle is not visible anymore. then you switch back to norm.
so it depends on the needle. if you don’t check the needles you can’t correct itagain, most flights don’t need that knob out of norm. It’s only pilot error in BMS that induce an imbalance. therefore that switch should always be on norm unless one screwed up switchology
(basically what the manual says).
Logical, i wrote the manuals
-
Thanks for this really useful information! I like logical explanations!
I did not fire any missiles as I was on a A/G training mission.
My loadout was:
2x AIM 9X
2x AIM 120C
2x 3 AGM 65D
2x 2 GBU 12B- Target Pod
- AN/ALQ 184
I defnitely dropped all of my A/G munitions as I got the CAT warning after dropping my last pair of GBUs and switched to CAT I accordingly.
I’m curious: what is your idea, that I will not like?
-
My loadout was:
2x AIM 9X
2x AIM 120C
2x 3 AGM 65D
2x 2 GBU 12B- Target Pod
- AN/ALQ 184
5. Bingo was 1.500
Fuel management and AI behavior (Secrets of “Dynamic Bingo”) Edit Blog Entry
Rating: 3 votes, 5.00 average.
0 Comments
by Dee-Jay
, August 26th, 2012 at 21:00 (1621 Views)Small tips for fuel management :
Simple and fast rough computation (only applicable for F-16):
-
At “standard” drag factor (around 150) and 480kts GS:
-
Below 5000ft = 20lbs/Nm
-
Between5000 and 25000 = 15lbs/Nm
-
Above 25000 = 10 lbs/Nm
More elaborated rough computation:
- If you are using a fuel rate value based on a clean configuration … add 30% for each 100 points of drag factor.
- If you are using a fuel rate value based on a fuel rate at sea level … subtract 10% for each 5000ft
Note: Very quick computation (may be inaccurate in some cases … just to have an idea) for an F-16 with a high drag factor flying around FL200:
Maximum basic target range for a straight ingress track:
- No fuel tank: Max target distance = 150Nm (max trip distance 300Nm)
- Center-line tank: Max target distance = 200Nm (max trip distance 400Nm)
- Two 370Gal wing tank: Max target distance = 250Nm (max trip distance 500Nm)
…
Just curious to know … what distance from airbase your target(s) was ?
-
is there a possibility that you were hit? or fragged by your own weapons?
when exactly did that shift occur then? at weapon release (which pair of GBU) or when you jetisonned all stores?
I defnitely dropped all of my A/G munitions as I got the CAT warning after dropping my last pair of GBUs and switched to CAT I accordingly.
I don’t understand that
if you say you didn’t fire any missile.I did not fire any missiles as I was on a A/G training mission.
But you released gbus in pairs, correct?
and you state you had the CAT light coming on after GBU release? but you still have 6 AG missile loaded right? so you can’t be out of cat configuration then.
Doesn’t make any sense to me
I doubt the jet is cat 1 with 6 agm65 still loadedwhen did you notice the shift
you release GBU in pairs? was the shift at the first pair release or the second?
did you sel jet or did you emergency jetisson?training mission? Not the default one from 4.33 then because i made them as well and i would never have loaded the jet like that for a training mission
The F-16 is short legged and needs fuel, the inner stations are meant for fuel, not for weapons. should you have done that, you would have had more fuel and probably made it home -
The shift was MUCH STRONGER (VERY MUCH STRONGER) than the usual shift. It was tremendous, not just a vague feeling. I do not exklude the possibility that it was a joystick failure
If it was a joystick axis failure it will happen again. I used to have same probs years ago with foxy controlled axis profile on hotas cougar when maby a combination of buttons sporadically drove left tremendous roll without obvious reason . Maybe its something like that.
-
Hey guys, come down a little bit!
I am a beginner and I created my own Kotar training scenario to train basic procedures all of you know by heart:
1. How to create a TE
2. How to perform a correct ramp start
3. How to perform a full procedure take-off
4. How to boresight Mavericks
5. How to use Mavericks using Handoff / VIS-Mode
6. How to drop bombs using TGP lasing
7. How to drop bombs without TGP using CCRP / CCIP mode
8. How to trim the jet
9. How to perform a full procedure landing
10. How to navigate via TACAN
11. How to perform an ILS landing
12. How to correctly power off the jetTherefore I created my very own training:
1. Start off of Yechon in the early morning (still dark outside)
2. Perform a full procedure take-off according the airport charts (Parot 5a departure)
3. Boresight Mavericks at my waypoint 3 (over a small town)
4. IP 4 as ingress point for KOTAR (coming from south, 20nm to Kotar)
5. STPT 5 as attack pointSTPT 15 for Vertical Target 1
STPT 16 for Vertical Target 2
STPT 17 for Target 7 (Rings)
STPT 18 for Target South (Helicopters)
6. First attack run: Vertical Target 1 with 2 Mavericks (2-ripple) using TGP/Handoff for the first two targets of Vertical target 1
7. Flying up to STPT 6 (20 nm north of Kotar) -> Turn around for 2nd attack run
8. Second attack run: Vertical target 2 with 2 Mavericks (1-ripple) using TGP/Handoff for the first two targets of Vertical target 2
9. Flying south to STPT 4 -> Turn around for 3rd attack run
10. Third attack run: Target 7 (Rings) with 1 GBU 12 (single release) using CCIP -Trim out the jet -> turn around quickly for another pass dropping another GBU 12 via CCIP
11. Flying north to STPT 6 -> Turn around for 4th attack run
12. 4th attack run: Free targets with 2 Mavericks using VIS-mode, firing one after the other
13. Flying south to STPT 4 -> Turn around for 5th attack run
14. 5th attack run: Target Target South (Helicopters) with 2 GBUs (pair release) using CCRP
15. Fly to Kangnung airbase by TACAN navigation -> to IAF NAMAE -> DME arc 12
16. Fly an ILS approach following the circle pattern to runway 08
17. Land on Kangnung in the dawn (nice sky at that time)(As you can see I did not have any A/G munitions left. I did not fire any A/A missiles so these remained. After dropping my last A/G munition the Master Caution light came up and the CAT warning. At this point I’ve switched to CAT I)
I did not change the fuel quantity and left it just as BMS set it for me when creating the TE. When I’m strictly following this flight plan, I get the Bingo warning right after my last attack run and land on Kangnung with 800 to 1000lbs left.
Last time I failed one of my attack runs which I repeated (what was wrong!) so I had approx. about 30 to 40 nm more to go and the fuel just was not enough for this.
The shift occured on my approach to Kangnung airbase while flying the DME arc right before hard turning into the 080 radial, having approx. 500lbs left. I still could have made it to the airbase if I hadn’t to deal with that shift, bringing me completely off-course. After switching ENG FEED to FOR (which I just did, because I did not have any other idea) and lowering the landing gear the shift was gone. I then declared an emergency and struggled to get back to my final approach course. I would have used runway 26 and would not have followed the circle pattern to runway 08. Having the runway just in front of me, flame out and crash.
I didn’t expect the jet to shift in that way so I was curious what could have caused this and what I could have done in this situation. That’s about it.
I’m learning and practicing and can’t consider EVERY aspect of this simulation at this stage. In order to practice I’ve tried to build a scenario where I can train different procedures.
I thank you very much for your replys, but hey, it’s still a game! And not everybody is on the same level as you are. I really appreciate all of your contributions as I want to get into this sim.
But sometimes (and I get that feeling from various other discussions on this forum as well) the postings sound like “Hey you stupid moron, you are doing everything wrong, so what do you expect?” Although this might be absolutely correct, it still doesn’t sound very nice.
PS: The color of my underpants is darkblue.
-
If it was a joystick axis failure it will happen again. I used to have same probs years ago with foxy controlled axis profile on hotas cougar when maby a combination of buttons sporadically drove left tremendous roll without obvious reason . Maybe its something like that.
Hopefully it will not happen again! But if it does, well, then I know for sure!
I have a shifting problem with one of my G25 pedals (using for rudder) which I can verify using calibration software. I know this is caused by debris on the potentiometers. Unfortunately my pedals are mounted by screws in my pit and I can only dismount them by going to the downside of the base plate. It’s a pretty heavy wood construction, so not an easy task…
-
Hopefully it will not happen again! But if it does, well, then I know for sure!
I have a shifting problem with one of my G25 pedals (using for rudder) which I can verify using calibration software. I know this is caused by debris on the potentiometers. Unfortunately my pedals are mounted by screws in my pit and I can only dismount them by going to the downside of the base plate. It’s a pretty heavy wood construction, so not an easy task…
A very small rudder input can provoke a massive roll
-
Just before comming down … I will end with this : the sim don’t compute the required fuel for you and won’t set your Bingo for you. This is your job.
I like the darkblue.
Cheers.
-
I had a problematic situation that ended in a fatal crash. It was all my fault, I wanted to get my last bombs on target and my fuel was then just not enough to return to home safely. I crashed 1/4 nm before the runway…
The situation was the following:
First the warning light AFT FUEL LOW came on. After approx. 1 min. the jet started shifting to the left side (similar to dropping a single heavy bomb or after firing a HARM missile, but A LOT STRONGER). I could still get into level flight and even get the jet to turn to the right, but it was almost impossible to hold it there as it would pull so strongly to the left.
I did not know what to do so I just switched ENG FEED from NORM to FORWARD. The jet still rolled to the left. As I was already approaching the runway I lowered the landing gear. At some point (I don’t remember for sure, I was overwhelmed by that situation) the FOR FUEL LOW light came on and the jet started to level out normally. The side shift was gone. Some seconds later, flame out and crash.
I guess that a fuel imbalance caused the strong shift. But as AFT is related to LEFT wing (and FOR is related to RIGHT), why would the jet turn to the left, if the left side is empty?
Also I would like to know what caused that the shift ended and the jet levelled out correctly again. Because both tanks were empty? Because I lowered the landing gear???I’ve read through the fuel chapter and the warning lights chapter of T.O. BMS1F-16CM-1. Unfortunately I neither found an answer to these questions nor any advice what to do if that happens again (apart from having a better look at my fuel situation next time!).
What do you guys think?
Ok, Folks, I have a theory…Burnz flamed out and the jet started to depart on the left wing, temporarily corrected by going to landing configuration.
His trying various things with the fuel switch was done after the supposed departure, not causing it.
He’s not saying the swerve was caused by ordinance release, he was comparing it to that.
RD, what I think he’s saying is that he didn’t fire any AA missiles. Also, that he had fired his Mavs, then dropped the other, then got stores warning. Am I reading that correctly, burnz?
The only flaw in the theory was that Burnz didn’t indicate control and instrumentation failure that you would see with the generator dropping offline, unless of course the EPU was active
Burnz, two more comments…unless your training area is very close to your airfield, a bingo o 1500 is way too low. Secondly, as I believe someone mentioned, in that situation you should have planned for a flameout landing -
the sim don’t compute the required fuel for you and won’t set your Bingo for you. This is your job.
Cheers.Thank you!
I was not aware of this. I assumed the basic fuel configuration is set accordingly to the flight route by BMS. I will add fuel planning to my flight preparations (oh yeah…).
-
His trying various things with the fuel switch was done after the supposed departure, not causing it.
CORRECT
He’s not saying the swerve was caused by ordinance release, he was comparing it to that.
CORRECT
RD, what I think he’s saying is that he didn’t fire any AA missiles. Also, that he had fired his Mavs, then dropped the other, then got stores warning. Am I reading that correctly, burnz?
CORRECT
Thank you for reading precisly!
unless your training area is very close to your airfield, a bingo o 1500 is way too low
I will have to learn about fuel management and will do that. That’s very clear to me now, after this discussion!
you should have planned for a flameout landing
Flameout landing is on my list of things to learn. I thought I would start with “easier” tasks first and move on to the harder tasks (like flamout landing) later on.
At the moment I’m still struggling with A/A refuelling and practicing this a lot.