My Own "Your the Captain"-----move there if you can please

Ecl!pse

Well-Known Member
My Own \"Your the Captain\"-----move there if you can please

Well, i dont know if i dont have privelege to post in the "Your the Captain" section, or if my computer is screwing up, so if this can be moved there i would appreciate it...Anyways, here is your scenario.



Your the captain on a 737-300, and you are on approach into the airport, in a downwind pattern for the runway. Your flaps are at "Flaps 1", and the spoilers and gear are retracted. You are told to be at 190 knots, and to go to heading 140. However, 4.5 miles ahead is another aircraft, in fact a "heavy".
In the turn to your left, you encounter wake turbulence. As you exit the turbulence, you give some right rudder to help straighten the plane out. However, as you push the pedal, it comes back against your foot. You've slowed down behind 190 knots now, and you now have a full rudder deflection (to the left). What do you do? (Hopefully this will also test your knowledge of 'yer boeing aircraft!)
 

N9103M

Well-Known Member
Re: My Own \"Your the Captain\"-----move there if you can please

You're basically presenting the USAir 427 scenario....
 

A300Capt

Freight Dawg
Re: My Own \"Your the Captain\"-----move there if you can please

[ QUOTE ]
You are told to be at 190 knots, and to go to heading 140

[/ QUOTE ]

That heading doesn't mean anything in relation to the landing rwy or the airplane you're following since you didn't supply that info.

[ QUOTE ]
As you exit the turbulence, you give some right rudder to help straighten the plane out

[/ QUOTE ]

What do you mean, "give some right rudder to help straighten the plane out."? Straighten out from what? What's the plane's attitude?

[ QUOTE ]
However, as you push the pedal, it comes back against your foot. You've slowed down behind 190 knots now, and you now have a full rudder deflection (to the left). What do you do?

[/ QUOTE ]

What do you mean, "comes back against your foot"? The rudder normally wants to center or "push" against your foot.

We have no idea what the attitude of the aircraft is when you state,"and you now have a full rudder deflection (to the left)".

I could think of many reasons for this, both normal and abnormal. What's the aircraft doing with full rudder deflection? Is it recovering or not?

Bottom line...we need a lot more info before attempting to answer this scenario.
 

Tired

New Member
Re: My Own \"Your the Captain\"-----move there if you can please

[ QUOTE ]
As you exit the turbulence, you give some right rudder to help straighten the plane out

[/ QUOTE ]

AA587 proved this to big no-no. Be careful with that rudder.
 

Ecl!pse

Well-Known Member
Re: My Own \"Your the Captain\"-----move there if you can please

Sorry, forgot some...And yes, this was the 427 scenario...

Your at 6,000 feet.


As for the rudder coming back against your foot, in the investigation of the accident, in the Boeing plant, while testing the rudder they slammed the right one, and it came back against his foot. It was something with the PCU valve, if I recall correctly.

Also for the right rudder, I think it was to adjust some slight heading problems..

Sorry for the lack-of-info, a newbie mistake
...Keep asking if you dont understand
 

B767Driver

New Member
Re: My Own \"Your the Captain\"-----move there if you can please

First...I would not use rudder (in a big jet) in a wake turbulence encounter recovery unless the event placed the airplane in a severe roll upset where the ailerons did not respond. The yaw damper should displace the rudder appropriately for most phases of flight. (Remember the AA airbus at KJFK...for some reason the first officer used aggressive rudder inputs for this recovery...much to the chagrin of airline pilots, training departments and aero engineers the world over.) This (rudder inputs) topic could fill volumes on another thread...but basically rudder inputs in big jets put the airframe at risk for a pilot induced oscillation and/or an unrecoverable dutch roll. Aircraft with swept wings are very susceptible to control problems with excessive rudder inputs.

Second...pertaining to the rudder hardover you are describing and how to recover. 1st...disconnect the autopilot and hand fly. 2nd...turn off the yaw damper. The autopilot will restrict control authority and the yaw damper uses a separate PCU.


I've seen this scenario when I was on the B737...in the sim...of course.
 

Ecl!pse

Well-Known Member
Re: My Own \"Your the Captain\"-----move there if you can please

Yeah, but I am not too sure as to why the right rudder was used..I did take 427's scenario, so i dont know why..As for the recovery, the crossover speed for the 737 is 190 knots, and they were below it when they were trying to recover...should we start a new thread in technical section for hazardous rudder imputs? might help some of us who arent quite sure about it..
 

Ecl!pse

Well-Known Member
Re: My Own \"Your the Captain\"-----move there if you can please

yeah, ive seen reports on that flight...they said that the rudder commandments were practically supernatural with the turbulence..like less than miliseconds.... i'll read into it more to see what was up

here is a website i have found with the cockpit voice recorder transcripts on it....

http://aviation-safety.net/cvr/transcripts.shtml
 

B767Driver

New Member
Re: My Own \"Your the Captain\"-----move there if you can please

The January 12, 2004 issue of Aviation and Week and Space Technology has a great article on rudder usage during attitude upset recovery. The article is on p.39 and is titled "Rethinking Upset Training". This magazine is found at most public libraries...it would be worth the trip to find the article.

Basically, the article stated that many airlines (prior to AA587) advocated the use of top rudder and full aileron to recover from a steep bank/roll upset. That maneuver can work okay in smaller airplanes but could have a devastating affect on larger ones.

Later in the article it states that Boeing, Airbus and MD issued recommendations in the late 1990's stating that pilots should use full aileron inputs to counter a lateral upset (roll) and to only add rudder if the aileron input was not sufficient to counter the roll.

(I do think this topic of rudder usage could be somewhat confusing for the small airplane pilot. The big transports typically have sophisticated stability augmentation systems that automatically correct yaw (with rudder inputs) to maintain coordinated flight. The big airplane pilot typically flies with his feet on the floor in normal maneuvering flight...in other words...no rudder inputs. Contrast this to the small airplane pilot...who in normal maneuvering flight is constantly conscious of rudder inputs...continuously applying rudder to keep the aircraft coordinated and aligned with its velocity vector.)
 
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