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Speedwinner
25th Apr 2015, 05:59
Hi folks ,

Quick one: how much rudder trim do I need in case of engine failure after go?

Thanks!

yoyonow
25th Apr 2015, 07:42
Quick one:-

Enough!

Nightstop
25th Apr 2015, 08:59
20 units of trim, it takes ages. 10 degrees of pitch initially, then as required to follow the SRS.

reptile
25th Apr 2015, 09:08
The blue beta target will replace the normal sideslip indication on the PFD during engine failure. Since the lateral normal law does not command the full needed rudder surface deflection, the pilot has to adjust the rudder pedals to center the beta target.

When the beta target is centred, total drag is minimized even though there is a small amount of sideslip. The calculation of the beta target is a compromise between drag produced by deflection of control surfaces and airframe drag produced by a slight sideslip. Centering the beta target produces less total drag than centering a conventional ball, as rudder deflection, aileron deflection, spoiler deployment and aircraft body angle are all taken into account.

Keep in mind that the yaw damper reacts to a detected side slip. This means that with hands off the stick and no rudder input, the aircraft will bank at about 5 maximum and then, will remain stabilized. Thus, laterally, the aircraft is a stable platform and no rush is required to laterally trim the aircraft. Control heading conventionally with bank, keeping the beta target at zero with rudder. Accelerate if the beta target cannot be zeroed with full rudder. Trim the rudder conventionally.

OPEN DES
25th Apr 2015, 09:10
15 for t/o
18 for g/a
7 for approach

Ballpark figures of course

ACMS
25th Apr 2015, 12:06
Funny, I was taught that trim is a secondary control? Maybe I'm misreading your intention?

1/ push rudder as required.

2/ trim out forces.

3/ relax foot.

You don't trim to move the rudder first.......:=

I guess it's handy to know how much rudder trim you will need but it's a SECONDARY control.

Kayvaan
25th Apr 2015, 13:03
ACMS, I think you are indeed misreading the intention:

"Quick one: how much rudder trim do I need in case of engine failure after go?"

Seems pretty clear cut to me, trying to get a ballpark figure. No need for holier than thou finger wagging.

OP, trainers have always taught me to hold it for about 10 seconds, then fine tune.

Cheers

Uplinker
25th Apr 2015, 13:26
If you are flying on one engine*, I think you should be looking ahead and at the PFD, and instruments, not looking down at the rudder trim control. Get the aircraft under control, (and centre the beta target), and then trim out any rudder control forces by feel.

The rudder trim does move very slowly though, about 15 secs for an EFATO situation.


*perhaps you are flying a desk top flight simulator, in which case it might be tricky to judge, hence your question?

ACMS
25th Apr 2015, 14:29
Ok yes it's nice to know how much you need for each situation I guess?

Me? I've never bothered to remember ball park figures, I know it's a lot on takeoff needing maybe 10 seconds and that its less at other times!!
I select the trim until the force is balanced out and the beta target centered................funny thing that it works......:sad:

I do that without looking at the trim indicator or counting!!!

If you need to "fly" by numbers to help you get started then that's fine to. :ok:

After a while "NIKE" just kicks in anyway.

vilas
25th Apr 2015, 14:31
Select TOGA, apply proper amount of rudder to zero Beta and only then hold the trim for count of 12, curl back your ball of the foot if rudder follows reapply rudder and trim few seconds more and fine tune. This will work if pitch is held steady. If you keep dropping speed rudder requirement will keep increasing.

ACMS
25th Apr 2015, 14:33
Ok Vilas but I hope you don't lose count half way!

Then what happens?:}

vilas
25th Apr 2015, 17:42
ACMS
He asked for a quick fix it so I gave it. Otherwise I have explained the method how to do it doesn't need any counting really.

ACMS
26th Apr 2015, 08:55
All good. :ok:

Gryphon
26th Apr 2015, 10:08
Select TOGA

:confused:

Not required! Sometimes even discouraged! Anyway not in a hurry.

Let's say "Consider TOGA"?

And of course it will be easier if you do it after the autopilot is engaged (if available)

vilas
26th Apr 2015, 12:38
Gryphon
Why is TOGA not required? Just because a test pilot who had good night's sleep and breakfast showed that you can clear obstacles by 35 feet with FLEX? Thank you. As long as TOGA is not charged to my credit card for I will use it.

Gryphon
26th Apr 2015, 18:31
TOGA is not required by OPS regulations (not talking about certification), the same way that it is not required to reduce weight if you can make it with TOGA even if you are not a test pilot. You even take advantage of the actual temperature compared to the assumed one. If you're using a derated take off procedure you cannot recover the max TO power and you aren't unsafe.

Consider TOGA? Yes, of course! :ok:

How is the aircraft climbing? Are there obstacles? Was the take off limited by climb gradient or Runway length? Do you need to over-stress the single engine? What was the reason for the dead engine to fail? How is doing the good engine?

Maybe you've hit a flock of birds. That's why you have an engine failure and you don't know how is affected the live engine.

Maybe...a lot of possible situations.

From my point of view, to teach "Select TOGA as per procedure" is not correct. You have to teach that it is not mandatory, because it's not.

In the other hand, TOGA has always to be considered, so "Consider TOGA" IMHO is the right way of thinking...and teaching.

It's just my opinion, nothing else. :cool:. And it's legal of course.

Stone_cold
26th Apr 2015, 18:40
Well Vilas , Gryphon is quite correct and you are quite arrogant ( typical when anyone offers up a different opinion ) to state that this IS the procedure . If it is your preference , then say so , but don't state/imply that it is the required or preferred technique .

If your takeoff perf was limited to TOGA , then you would have to accept the "test pilot's " 35 ' , wouldn't you ?

JABBARA
26th Apr 2015, 19:54
A humble contribution:

1. TOGA is not allowed if Derated Take off, because Vmca is assured for rated thrust only for selected derated thrust.

2. 35 feet clearance is achieved after net climb gradient, whereas gross (practically you can say actual) gradient is +0.8% (for twins). So your actual clearance from obstacle will be well above.

3. If I had been tethered to life with only one remaining engine, I would behave it very well and smooth, not TOGA unless it is absolutely necessary.

vilas
27th Apr 2015, 02:36
OK Let me clarify what I said. My first post was how to trim in optimum situation in EFATO which is TOGA. I did not say it is mandatory. Flex take off obviously meets certification requirements. As far as Airbus is concerned they ask you to consider TOGA. If you read my statement again it is not offensive but in favour of line pilot's realities of life. Early morning flight, lack of sleep, late night flight may be 5th take off, extreme tiredness these are not the conditions in which test flights are done. So in these conditions when you are faced with once in a life time event you would like to insure a yourself with a bit more. If you are one of those whose flying is perfect 365 days anytime and every time then my apologies my advise was not meant for you. Derate is a different matter we were not discussing that. Just like flex is certified TOGA power is also certified for use any time you want.

john_tullamarine
27th Apr 2015, 03:47
Some thoughts. Caveat - no specific Airbus background

As long as TOGA is not charged to my credit card for I will use it.

Fair comment, but consider -

(a) certification philosophy is that there is no need for pilot commanded thrust increase due failure and, indeed, the Standards proscribe it. This, naturally, doesn't preclude operation of those systems which have an auto thrust increase capability.

(b) flex sums are based on no increase in thrust. If you choose to increase thrust, suggest you do so slowly.

(c) derate sums are based on no increase in thrust. Vmca may, and generally will, have been reworked for the derate. If you choose to increase thrust beyond the derate maximum, then do it very carefully and know what the actual Vmca was for the takeoff

Why do I say do it carefully ? Thrust can ramp up rapidly with an accompanying Vmca ramp up and catch the pilot quite unawares. I was involved in a turboprop fatal investigation many years ago where, almost certainly, the final departure which led to ground impact was associated with too fast a pilot commanded thrust increase on a very good engine .. crash, burn, (most) die.


35 feet clearance is achieved after net climb gradient

.. once you are in the climb. A V1 failure doesn't give you much fat to play with at the end of the takeoff ... different matter once you are through several hundred feet on the altimeter.


If you are one of those whose flying is perfect 365 days anytime and every time

Another fair comment. I can recall only two pilots who might have come close to this. Flew with one a bit with attendant embarrassment on my legs ... most of us fall far short ...

Skornogr4phy
27th Apr 2015, 11:40
With the FLEX and TOGA detents being switches on the Airbus aircraft being switches (on or off) not variable levers, your point about increasing thrust slowly john_tullamarine is simultaneously more important, and also impossible :bored:

vilas
27th Apr 2015, 12:32
Skornogr4phy
What John said is in general. If you are in control of the aircraft laterally and vertically A320 creates no problem with TOGA. If your attitude is increasing and speed is decreasing you need more and more rudder if you add TOGA you may get in trouble. Being FBW it selects the max acceleration schedule when you put it in TOGA. If you move slowly the acceleration follows the TLA. One needs to be careful at lighter weights (grey strip) as speeds are closer to minimum control speeds . You cannot get an easier aircraft to fly with OEI than Airbus.

JABBARA
27th Apr 2015, 12:39
Skornogr4phy

Are you sure about that?

It is definitely incorrect for a T/L position above MCT detent in the case of OEI. FMA "MAN THR" mode engages, and thrust can be controlled manually by T/L at any place between MCT and TOGA. Of course LVR THR flashes and A/THR disarms (blue).

However the case what you said is at Take off and when FLEX is used with MCT detent. So it may be different than what I know. But logically in that case as well, since the A/THR is still at ARMED phase (blue), thrust may be controlled somewhere between FLEX and TOGA.

regards

Skornogr4phy
27th Apr 2015, 13:59
I was getting confused, thanks JABBARA. Got my recurrent sim in a week so I should really get some work done on that.

JABBARA
27th Apr 2015, 14:10
I am sure you will do good job sir

:ok:

Amadis of Gaul
29th Apr 2015, 01:18
I wouldn't overthink it. Use as much trim as it takes, numbers be darned.