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Moscow Passenger Plane Catches Fire, Crash-Lands in Cornfield.

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  • Evan
    replied
    Originally posted by ATLcrew View Post
    There were some serial numbers that had landing gear on the yellow system, I believe the Smurfs have a few, that might explain why your QRH says what it does.
    Qatar, rev 40. But it also indicates 'no gear retraction' for G + B, so I don't think it is matter of which system powers the gear.

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  • ATLcrew
    replied
    Originally posted by Evan View Post
    There are priority valves that shut off the heavy users (flaps, slats, gear) when the pressure is low, to preserve flight control. But that doesn't explain the B + Y thing. This was listed in the QRH I have for GA after the B + Y failure. OBVs not the same version you have.
    There were some serial numbers that had landing gear on the yellow system, I believe the Smurfs have a few, that might explain why your QRH says what it does. It bears mentioning that a B +Y failure would take some doing outside of fluid loss (and then to lose fluid in both of them would be quite a task). Even to just lose Y outside of the above-mentioned overheat from the G side scenario would be no easy task without a leak. It would take three separate failures for that to happen (EDP2, Y ELEC pump and the PTU). At least G and Y are connected somewhat at the PTU, B and Y are not connected anywhere.

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  • BoeingBobby
    replied
    You guys are funny!

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  • Evan
    replied
    Originally posted by ATLcrew View Post
    Ours doesn't indicate that, it indicates gear EXTENSION gravity only "to preserve system integrity", retraction is not mentioned at all. I don't know if it's necessarily because of the PTU or just because to minimize load on the system in general.
    There are priority valves that shut off the heavy users (flaps, slats, gear) when the pressure is low, to preserve flight control. But that doesn't explain the B + Y thing. This was listed in the QRH I have for GA after the B + Y failure. OBVs not the same version you have.

    As for load, the best I could find was this badly designed chart in an engineering article presenting a case for Variable Displacement Hydraulic Motors. The text indicates that this chart is based on an existing 'typical load profile for a civil transport aircraft'. The light yellow is 'available flow' based on the engine power setting. The dark blue are the 'required flow' levels for the items listed to the right. You can see that the gear retraction requirement exceeds the available flow at approach power settings, so I would expect this to also be true after a bird strike-induced power reduction.

    Click image for larger version

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    Glossary for 3WE:

    B- Blue
    Y- Yellow
    GA - Go Around
    OBVs - Obviously
    3WE - Undefined

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  • Evan
    replied
    Originally posted by 3WE View Post
    Please note: ISGPOTM

    (I know, it deviates from normal, fundamental procedure, BUT, that's how it's traditionally been done on aviation fora and we have to be type specific).

    TISGPOTM is also acceptable- the copyright for TOSU has not yet been ruled upon.
    Noted.

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  • 3WE
    replied
    Originally posted by Evan View Post
    FXD
    Please note: ISGPOTM

    (I know, it deviates from normal, fundamental procedure, BUT, that's how it's traditionally been done on aviation fora and we have to be type specific).

    TISGPOTM is also acceptable- the copyright for TOSU has not yet been ruled upon.

    Leave a comment:


  • Evan
    replied
    Originally posted by 3WE View Post
    Razzing of my disdain for acronyms is acknowledged.

    However, may I cite a recent post of the ISGPM, where he suggested that pilots might read more, study more and learn more if AFM's were written better and more clearly.

    And may I RPT that at the PPYML, some pilots might focus very hard on memorizing that important stuff to the detriment of other important stuff like: RPUs have a moderately strong correlation to stalls. They then go on to adequately demonstrate the RN on the COMCHK for whatever rating, and then go and do a VGJ of FUA, except for those SURBSRCI's.

    I don't know that RPUHAMSCTS is really helping the learning process for the FHM.
    FXD

    Leave a comment:


  • 3WE
    replied
    Originally posted by elaw View Post
    My VHS VCR doesn't get MTV. Is that a problem?
    Originally posted by ATL
    No, because MTV sucks.
    Dude...you have not lived until you have a DVR.

    Indeed, MTV sucks...sadly VH1 is not much better.

    Let's not forget CNN, ESPN, ABC, CBS, NBC, TWC, HBO, TMC, TCM...

    Leave a comment:


  • ATLcrew
    replied
    Originally posted by elaw View Post
    My VHS VCR doesn't get MTV. Is that a problem?
    No, because MTV sucks.

    Leave a comment:


  • elaw
    replied
    My VHS VCR doesn't get MTV. Is that a problem?

    Leave a comment:


  • 3WE
    replied
    Originally posted by Gabriel View Post
    Just joking, I am not as an acronym-phobic guy like our aggie friend.
    Razzing of my disdain for acronyms is acknowledged.

    However, may I cite a recent post of the International Super Genius Pilot of the Millennium, where he suggested that pilots might read more, study more and learn more if aircraft information manuals were written better and more clearly. (Not a quote, but I think that was the essence.)

    Somehow, I think they (not we) can write better than "OEB + ECAM's OEB reminder for when such change is not in place. I got the MOD 34236 + 35879 / SB 29-1115 and MOD 35938 / SB 29-1126" and "NAV ADR DISAGREE ECAM83% N1 alpha prot AoA RECMAX THRUST RED ALT WTF".

    And may I re re re re re re re re re re re re re re re re re repeat that at the puppy mill, some pilots might focus very hard on memorizing that important stuff to the detriment of other important stuff like: relentless pull ups have a moderately strong correlation to stalls. They then go on to adequately demonstrate the required knowledge on the competency checklist for whatever rating, and then go and do a very good job of flying us around, except for those seemingly unbelievable, rare-but-somewhat-repeated crash incidents.

    I don't know that RPUHAMSCTS is really helping the learning process for the flawed human mind.

    Leave a comment:


  • ATLcrew
    replied
    Originally posted by Evan View Post

    Also, do you know why the QRH procedure for HYD B + Y SYS LO PS indicates no gear retraction? I'm wondering if it is because G can't operate the gear and the PTU simultaneously.
    Ours doesn't indicate that, it indicates gear EXTENSION gravity only "to preserve system integrity", retraction is not mentioned at all. I don't know if it's necessarily because of the PTU or just because to minimize load on the system in general.

    Leave a comment:


  • Evan
    replied
    Originally posted by Gabriel View Post
    Just joking, I am not as an acronym-phobic guy like our aggie friend.
    I know. That wasn't directly at you. I shouldn't have 'replied with quote' there.

    Leave a comment:


  • Evan
    replied
    Originally posted by ATLcrew View Post
    You're close, but you missed the key point of this only being an issue if the hydraulic failure is due to loss of fluid. The PTU can power the green system all day and all night if there is no fluid loss. The scenario in the OEB happens because the PTU is trying to pump fluid that is not there, and THAT is what causes it to overheat very quickly. If we lose ENG1 or EDP1, the PTU will power the Green side no problem at all if there is no fluid loss. The same is the case with the yellow system. So, we can lose ENG2, EDP2 AND Y ELEC PUMP 2, and STILL not lose the yellow system as long as there is no fluid loss. With the modded airplanes, we will lose the Green system until we cross 1,500 feet and the PTU picks it back up, so it doesn't JUST fail. Again, assuming there was no fluid loss.
    I see. HYD G SYS LO PS caution doesn't distinguish whether the LO PS is due to pump failure or fluid loss. Maybe it should read LO FL and inhibit the PTU whenever that condiition is present. It seems to me that the logic could distinguish between the two.

    Also, do you know why the QRH procedure for HYD B + Y SYS LO PS indicates no gear retraction? I'm wondering if it is because G can't operate the gear and the PTU simultaneously.

    Leave a comment:


  • ATLcrew
    replied
    Originally posted by Evan View Post

    So, in the event of a loss of the green hydraulic system immediately after takeoff, the scenario I brought up here, the green system would lose pressure and the pressure differential would cause the PTU between the yellow system and the green system to automatically activate, but the PTU is not designed to power the green system for an extended period like this, it's just there to supplement transient drops in pressure, and running it for any length of time will overheat the yellow system as well. Now you've lost both engine-driven systems and all you have left is the blue system for flight control. Not a great situation. So, in this scenario, the PTU must be deactivated asap, but, since Airbus defers ECAM caution messages below 1500' to avoid distractions, the pilots will most likely not be aware of the situation until both systems fail. The solution Airbus came up with is to inhibit activation of the PTU below 1500', as a recommended modification. So now, if the green system fails below 1500', it just fails, while the yellow system remains healthy. Thus, no gear retraction, which uses the green system (if the gear is still down).


    So, ATL, do I have that right? Or please correct me on this.
    You're close, but you missed the key point of this only being an issue if the hydraulic failure is due to loss of fluid. The PTU can power the green system all day and all night if there is no fluid loss. The scenario in the OEB happens because the PTU is trying to pump fluid that is not there, and THAT is what causes it to overheat very quickly. If we lose ENG1 or EDP1, the PTU will power the Green side no problem at all if there is no fluid loss. The same is the case with the yellow system. So, we can lose ENG2, EDP2 AND Y ELEC PUMP 2, and STILL not lose the yellow system as long as there is no fluid loss. With the modded airplanes, we will lose the Green system until we cross 1,500 feet and the PTU picks it back up, so it doesn't JUST fail. Again, assuming there was no fluid loss.

    Leave a comment:

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