B737 Talk

flyinggreasemnky said:
This is a very common MEL on the MD11 and it has posed a problem when the math is done wrong when they stick the tanks. There have been a couple of diversions and rollbacks caused by not having enough fuel. It was even a problem for an ACMI 747 operator when they were flying over Pakistan and had one roll back. The amount of fuel they had when upon landing in India was startling to say the least. Honestly, the chance of them getting the math wrong when sticking the tanks is the greater risk.
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Go out there sometime when they are sticking the tanks. Or don't if you want to sleep better.
 
Roger Roger said:
Don’t have to fly the missed if you don’t go missed

*for legal reasons this is a joke
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I literally used this yesterday in the simulator when we were running behind time, the FO was walking me through the single engine missed approach procedure, interrupted and said "I'll get us straight out to 3000 feet over the water and don't go missed! Ha!"
 
derg said:
I literally used this yesterday in the simulator when we were running behind time, the FO was walking me through the single engine missed approach procedure, interrupted and said "I'll get us straight out to 3000 feet over the water and don't go missed! Ha!"
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I mean, sometimes especially when things are dire this is an extremely valid strategy.

I’ve also been to quite a few places where if you end up having to miss after the MAP you might die if you try to turn back over the airport and climb? Sometimes “get over low terrain and climb” is a fantastic strategy.

That’s why it’s good if pilots are critical thinking humans rather than just procedures robots.
 
mikecweb said:
Go out there sometime when they are sticking the tanks. Or don't if you want to sleep better.
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I know in the ACMI incident, they stuck the tanks but didn't realize that you don't add the sticks together but only use the farthest one's level to calculate. Ride-a-long Mechanic told me about his previous mistake while we were flying over the Pakistan/India border. You wouldn't catch it unless you could hear the math he did in his head. On one of the MD11 incidents, the captain had the hair on the back of his neck standing up. He kept telling them that something wasn't adding up but after over an hour delay, the fueler, Mx, MOC and management convinced him that he was good to go. You can imagine how unhappy he was after their diversion.
 
Maximilian_Jenius said:
What is a stuck tank?
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When there is a fuel quantity MEL the only way to see how much fuel is in there is to fuel to a known quantity or to "stick the tanks". That process involves tabulated data based on lots of items including the slope of the surface and then measure sticks are unscrewed from the bottom of the tank. The English language takes over from there, I guess stuck tank works.
On a good day the guys in ties just need to look at a fuel slip and confirm it looks good and trust the process. The "process" has proven to not be trustworthy however.
 
mikecweb said:
When there is a fuel quantity MEL the only way to see how much fuel is in there is to fuel to a known quantity or to "stick the tanks". That process involves tabulated data based on lots of items including the slope of the surface and then measure sticks are unscrewed from the bottom of the tank. The English language takes over from there, I guess stuck tank works.
On a good day the guys in ties just need to look at a fuel slip and confirm it looks good and trust the process. The "process" has proven to not be trustworthy however.
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Interesting how different airlines do things differently, here the captain has to go out and watch and verify them when the dripsticks are used. MEL'd fuel gauges happened a lot on the classic and that thing had true dipsticks vs the NG which have floats in them.
 
arkflyr said:
Interesting how different airlines do things differently, here the captain has to go out and watch and verify them when the dripsticks are used. MEL'd fuel gauges happened a lot on the classic and that thing had true dipsticks vs the NG which have floats in them.
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I watched it once walking around as an FO just for •s and giggles and it was not confidence inspiring.
 
Here's one for you guys that I haven't been able to find in any of our manuals or Cockpit Companion.

When you go to flaps 40, the roll rate increases noticeably. My gut tells me it has something to do with flight spoilers, but I can't seem to find what.

Anybody know what it is that makes the airplane squirrly in roll at flaps 40 compared to 30?
 
ZapBrannigan said:
Here's one for you guys that I haven't been able to find in any of our manuals or Cockpit Companion.

When you go to flaps 40, the roll rate increases noticeably. My gut tells me it has something to do with flight spoilers, but I can't seem to find what.

Anybody know what it is that makes the airplane squirrly in roll at flaps 40 compared to 30?
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I haven't noticed this but I'll try more flaps 40 landings and see. No idea why it would increase the roll rate.
 
There was a similar thread on PPrune a decade ago. B737-800 with Flap 40: what causes increased roll sensitivity? - PPRuNe Forums

Speculation included:
  • "aerodynamic twist" (?) biasing the neutral position of the ailerons. I interpret this idea to mean that the wing-down commands are being biased closer to the mechanical rigging point where spoilers are also deflected, possibly because of different torsion around the span of the wing as flaps move the CP.
  • Flaps 40 causes an increased portion of lift to be generated closer to the aircraft centerline, which I think is a restatement that the stability from wing dihedreal is reduced.
 
Do flaps 40 landings fairly regularly, haven’t noticed anything spectacular with them.
 
MikeD said:
Do flaps 40 landings fairly regularly, haven’t noticed anything spectacular with them.
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Ok, well that's interesting. Maybe it's all in my head. Other 73 drivers, what do you think? Does the roll rate change, or the aircraft seem more sensitive in roll at flaps 40?
 
ZapBrannigan said:
Ok, well that's interesting. Maybe it's all in my head. Other 73 drivers, what do you think? Does the roll rate change, or the aircraft seem more sensitive in roll at flaps 40?
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Like I said. I haven't noticed. I try to mix up all my landings so I'm always rotating between 15, 30 and 40. Usually I'm configured on final so I'm not really rolling around much. So haven't noticed. Maybe there will be a small wing wag on final tonight haha.
 
I’ve not noticed it…but next trip I’ll see what it feels like.

Flap 15 landings are becoming one of fav things to do
 
From my friend at Boeing:

Is more roll sensitivity at flaps 40 compared to 30 a thing?

“Yep. It's because flaps 40 is deeper flap angle and the flow breaks down a little quicker. It still meets the regs for roll control and nonlinearity is out past where you will be with the wheel.”

“We also used to have a lateral trim issue at flaps 40 due to the side of body. I think that is pretty much gone now. Max with fbw spoilers removes the twitchiness”

“Roll non linearity is going to be out beyond 2/3 wheel. You guys typically don't operate beyond 1/4 wheel”


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BEEF SUPREME said:
From my friend at Boeing:

Is more roll sensitivity at flaps 40 compared to 30 a thing?

“Yep. It's because flaps 40 is deeper flap angle and the flow breaks down a little quicker. It still meets the regs for roll control and nonlinearity is out past where you will be with the wheel.”

“We also used to have a lateral trim issue at flaps 40 due to the side of body. I think that is pretty much gone now. Max with fbw spoilers removes the twitchiness”

“Roll non linearity is going to be out beyond 2/3 wheel. You guys typically don't operate beyond 1/4 wheel”


Sent from my iPhone using Tapatalk
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Thank you! That was very helpful. Not what I expected but still helpful.
 
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