[solved] Braking action (Y/G) not on relevant Yellow or Green system

  • Hello,
    I'm doing ground school at the moment only, and never took off for the moment. 🙂
    I have two problems :

    1. AD and AC pumps do not have the same effect on putting parking break under hydraulic pressure (the FCOM says both pumps be used to top of the pressure) - QUESTION 1 it's like the DC pump has zero effect on the yellow system as modeled ?
    2. the brake circuits shows pressure even if setting PARK BRAKE ON cannot stop the plane from rolling. I agree the pedal pressure is not necessarily the brake pressure, due to anti skid effects, but it should be no factor here.

    My situation is :
    -starting from cold and dark on a slightly sloped apron (LPMA Madeira)
    -the BAe 146 drifts slowly.
    -With PB set, the Yellow brake pressure (main panel gauge) rises > 3000 psi but the planes does not stop.
    I go up quickly on the overhead, rushes to electric hydraulic pumps to provide yellow Hyd pressure (OVHD gauge), and now, the airplanes stops. That is expected.
    QUESTION 2 Is it correct to have the brake pressure rising on the main panel brake indicator, but no pressure in the system, from the OVHD gauge, or is it a bug ?

    EDIT : now I am in the situation to try again, this time with brakes on the GREEN CIRCUIT.
    With engine 3 and the PTU pumps off, I can see on the overhead 0 PSI for the green system, as expected. Still when selecting parking brake on the green system and applying them, the pedal pressure indicator rises. The plane stops effectively only if the AC pump is made active and pressurises the YELLOW SYSTEM.
    The AC pump made active (the PSI rises on the overhead indicator) makes the YELLOW rising, not the green. However, my aircraft is stopped by the green brakes, although is should not stop on the green system this time, having no pressure in it.

    EDIT : I have just tested the reverse, having pressure in the green due to engine 3, and no pressure at all in the yellow system, I can still brake on Yellow brakes, provided I have pressure somewhere.

    • Conclusion, as modeled here, yellow and green brakes are not truly coded, and both brake settings 'Y or G', do not care if it really has pressure in the correct, corresponding, system, each brake start to have braking effect with any of the two hydraulics pressures behind.
      QUESTION 3 Something is perfectible here I guess in the simulation, or I am mistaken ?

    What is encouraging is that I've check the correct attribution in the simulation of stairs to the Yellow Hyd System and AIrbrake to the Green one.
    -> However, the side cargo door fails the test, it is (page 15.22, diagram, FCOM) linked to the green system, but here in the simulation, it opens, even if no hydraulic system is pressurized.

  • Same situation here. I think a solution would be to have a chokes option. It lets us time to give pressure to the break system.

  • Sure, we need chocks, so I use my low tech ground service plugin for that, and applying chocks at the beginning is coded in Speedy Copilot for the Whisperjet too (unreleased yet).
    I believe this is normal.

    What is not normal, from my understanding, when I read the FCOM diagrams, is that :

    • green brakes works even if only yellow system is pressurized (🍰 report number 1)
    • yellow brakes works even if only green system is pressurized (🍰 report number 2)
    • cargo freighter door can open even if the green system isn't pressurized (🍰 report number 3)
    • HYD DC pump cannot be used to (less efficiently, because the pump is in a remote location in the circuit) top up hydraulic pressure like the AC pump. (I didn't test effect in the air so far). (🍰 report number 4)
      -- An also, maybe (not sure here) :
    • the pressure rises on the brake pressure indicator, but no pressure in the system is reported from the overhead gauge (all hydraulics pumps off). (🍰 report number 5, uncertain)

  • So continuing my review of the flight deck safety procedure, and found two other problems :
    on the ground test overhead panel,

    • the ANTI SKID FAULT YELLOW test works with effect on the ANTI SKID FAULT annunciator. Almost good, but on top of that, the documentation says that "Lift spoilers will deploy if the associated hydraulic system is powered", and I can see that the lift spoilers are not deployed in the simulation, having both hydraulic system pressurized (via the AC pump and the PTU) in my aircraft. (🍰 report number 6)
    • the ANTI SKI FAULT GREEN test button has no effect at all it seems (ie no MWS attention getting light, no MWS amber caution light, no ANTI SKID FAULY annun). My aircraft seems not dispatch-ready as a consequence.. (🍰 report number 7)

  • Continuing my review of the systems,
    now on the air conditioning panel,

    • wonderful, opening the aircraft doors actually make the temperature rising (with external temperature 37°C at the Red Sea) when the packs where set to provide a cold cabin temperature
    • with no packs, my cabin jumps to 37°C (same as OAT)

    So the product specs were not lying. Impressive.

    Automatic and manual pressurisation modes with control of outflow valves, barometric and cabin rate settings, indications and cabin altitude warnings
    Cabin altitude and differential values based on real-world data
    Automatic and manual flight deck and cabin temperature control, which takes account of ambient temperature, air supply from the engines and/or APU, fresh or recirculated air and even whether the doors are open!

    Continuing with the pressurisation I find a new problem
    -> I switch to manual and cursor to SHUT (to close both outflow valves while PACKS running, doors closed) but the indicator on the first officer main panel stay at 0 : the cabin climb rate does not change. By closing both outflow valves, I should inflate the cabin (and relatively get a descending cabin to a lower cabin altitude than the ambiant air).
    Here it is not possible to inflate the cabin. (🍰 report number 8 )

    I bring all of that here because I'd lke the product to be the best possible. I hope the developers while take that positively and bring an answer, in order to, if acknowledged, bring an even better product via an update. 90 % of the job is done, but certain things on my PC do not work as expected, or maybe it's me.

  • Hi All,

    I'm Joseph, one of the devs. Thanks for the great feedback, XPJavelin!

    We're introducing some improvements to the braking system simulation, which should help with these items. In the new system it will be possible to watch the brake pressure indicators directly following the hydraulic system pressure in the case of the Green system, and following the brake accumulator pressure in the case of the Yellow system.

    We're also adding wheel chocks (those may actually already be in v1.0.5, but if not they'll be in 1.0.6).

    I'll also add an item to make the cargo freighter door require hydraulic pressure; I think currently it doesn't. But it will!

    I'll have to see what we can do regarding the pressurization system. We are currently limited by X-Plane's behavior, but I'll see if I can find some workarounds.


  • @NoJoe
    Nice Joseph, I was confident something was about to happen and elected to be patient.

    I understand, regarding the pressurization. I was just trying to make your airplane the best in league, so we can absolutly advertise you work as the best classical airliner, the more accurate one, in X-Plane 🙂 I wish you the biggest success possible and I'd like to contribute to that.

    I did not test in flight, and as soon as possible, I'll work the effect of various non normal handling of hydraulics and press to gather my consciousness of what is simulated, and what not. Of course, not everything can be perfect, unless it's a 10 year project. So is the nature of informatics.

    it mays sound strange, but still one week after buying the aircraft, I still never took off. Ground schooling and all... Working furously on testing my automated Flight Deck Safety procedure, which is fully coded now in Speedy Copilot. The other procedures are usually easier and shorter to code than the initial power up.

  • So having tested 1.0.5, now indeed each brake doesn't reach a high PSI value when the corresponding side isn't pressurized. Good.
    Very very nice to take into account the hydraulic yellow brake accumulator.
    I'm surprised that (new in 1.0.5) the airplane is effectively braked with only a few PSI in the brake system (also true in the green with no direct accumulator in the vicinity of brakes), I would have expected this few PSI to be not enough to effectively brake. But maybe it's the same in the real aircraft ? 🙂
    I'm a little concerned that green brake pressure is able to rise when I never apply pressure in the green system at all from cold and dark. (🍰 report number 9 )
    I'm a little concerned too that when the yellow accumulator is back on low pressure (great simulation here of the accumulator), I'm still able to increase the yellow brake pressure, and not revert fully to a state similar to the cold and dark aircraft (🍰 report number 10 ) where everything is as expected : no pressure = no brake.

    I'm am pleasantly surprised to see the effect of the DC pump clearly, marked on the yellow brake accumulator (the low light extinguish upon DC pump activation) ! great great great !

    Plenty to read

  • Hi XPJavelin,

    Thanks for the very details reporting. This can be a tremendous when trying to stamp out bugs, or simply learning systems.
    The Braking System has undergone a large upgrade. This may very well still need some more work in due course.

    With regards to the amount of PSI required to hold the Aircraft, I can testify that with low thrust, only a few hundred PSI is needed to keep it stationary. Different story at Ref Thrust.

    The Yellow Brake Accumulator pressure loss and the ability to regain Brakes at the same time, I believe, is a function of the system. The Brake Accumulator re-pressurises in almost a blink of the eye in the real aircraft. I think this is what has been coded here. Unless I'm mistaking your statement?

    I've done a few tests with the Brake System. With the Green system de-pressurised, I'm unable to get any Brake pressure on the green system.

  • Hi,
    I've retested brakes behaviour now in v1.0.6 and you've nailed it. Everything behaves as I understand it from the manuals. So far so good ! I love the yellow system brake pumping effects. Amazing !
    One day I'm sure I will have time to takeoff and fly with it, so far since release, I'm enjoying the brakes simulation. 😃 😃

    I mark the topic as solved, yet the pressurization item isn't.