Primarily for general aviation discussion, but other aviation topics are also welcome.
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#1840659
IMCR wrote:My expectation is that in many types the roll will be slow, and control maintenable with full or close to close aileron. Dont attempt to land with any cross wind because you will run out of authority. Fly the approach faster to maintain authority. There are accounts and pilots who have survived.


I dont know about that.

I just happen to have flown a DR400 where on the ground on a walk around, it was virtually impossible to see that one flap had actually been slightly bent on the outer tip. This was literally less than half a centimetre of deflection on the last 6-12 inches of one flap at the tip. The aeroplane was cleared safe to fly by our engineer, but I absolutely noticed a distinct pull to one side in "level" flight - Such that you either had several pounds of constant side pressure on the stick or on the rudder to keep the aeroplane straight and level.

I hate to think what the full width of flap at 1st stage or worse full flap would produce in terms of adverse control issues.

Regards, SD..
#1840667
Assymetric flaps on takeoff roll, rotation or go-around at solw speeds will not be funny but it should be non-event on base or final at faster speeds...

One can get an estimate of min assymetric controllability speed on SEP by kicking full rudder with ball toward corner and keeping wings level with ailerons on full power climb or power off descente, usually it's not more than 5kts-10kts above stall speeds even toward P-factor side and it is with assymetric ailerons at the far end, I doubt one will just lose the aircraft with assymetric flaps if airspeed is faster but it could happen if flaps goes assymetic down in base to final turn, speed drops and ailerons twist then elevator pull are used to correct the ball instead of the rudder...

As long as one fly higher than that speed they are allowed to be sloppy on the rudder conciously on sideslip or without noticing but they need a slap on the face if they go slower without properly using their feets to keep the ball in the center !

One can call that Vmca for single engines :lol:
#1840672
Flyin'Dutch' wrote:

Asymmetric flaps are likely to be a terminal event.


‘Met the widow of the pilot who had this happen approaching Norwich in a Cessna 310.

So I have always advised my students to avoid applying flap while in a banked attitude.
In the level attitude you have a better chance of detecting uncommanded roll before it goes too far.

At one event a flight test examiner related a story about a Cessna 152 incident where for whatever reason the aeroplane had an asymmetric flap condition.
They successfully returned to the airfield in a cross control - slip.
I was glad of that story; to be able to relate true events is always better.
Image

This is the flap actuation cable on a Bellanca Cruisemaster.
Having had clutch cables fail in old cars that were thicker and made in the same way, I’d be very wary of the danger of asymmetric flaps especially as the flaps are very powerful in this type. Pay attention to the flap limit speed.
Ibra liked this
#1840676
Assymetric flaps on takeoff roll, rotation or go-around at solw speeds will not be funny but it should be non-event on base or final at faster speeds...


I’d be careful with this idea.

Are your ailerons more effective at higher speeds?
Can you roll faster?

Do an aileron roll at say 120 knots...
Now try it at 60 knots...

If you have a sudden asymmetric flap failure at higher speeds you may have enough aileron to counteract the roll, but do you have the reaction time?

The Cessna 310 probably was into the ground before the pilot realised what was happening.

If there’s sufficient aileron throughout the speed range to counteract an asymmetric flap condition, then surely at a lower speed the pilot has more time to recognise and react to uncommanded roll.
#1840679
Yes assymetric flap is a serious problem at slow speeds (surprise on base/final, rotation, climb) no question about that, at high speeds ailerons could do the job

At slow speeds, ailerons are not effective anyway and besides any roll at slow speeds has to be countred by the rudder, touching ailerons in the heat of the moment for slow speeds is the wrong place to start whatever the underlying source of that uncomanded roll...

Where the speed cutoff between effective ailerons & effective rudder sits is up to the pilots to find for their type
#1840680
While in the RAF we had to inspect the flap actuating arms on the Dominie fleet as there had been a case with a civil 125 where it had actually rolled because one side had failed on flap selection. Happily I think it was a test pilot who was flying - he was quick enough to deselect flap (i.e. undo the last thing he had done) and recovered it safely.

But it's not always at a good height - I do recall the Ambassdor at Heathrow in 1968...
#1840691
proteus wrote:
Flyin'Dutch' wrote:
Asymmetric flaps are likely to be a terminal event.



I too would like to see data for this. I know a chap who had this issue a few times and it wasn't terminal.


Asymmetric flap deployments are rare, yet you claim you know a chap who had this several times.

Show us the incident reports.
#1840692
Ibra wrote:Yes assymetric flap is a serious problem at slow speeds (surprise on base/final, rotation, climb) no question about that, at high speeds ailerons could do the job

At slow speeds, ailerons are not effective anyway and besides any roll at slow speeds has to be countred by the rudder, touching ailerons in the heat of the moment for slow speeds is the wrong place to start whatever the underlying source of that uncomanded roll...


You are correct about the use of rudder at the slower speeds.
However effective the ailerons might be at the higher speeds, the roll effect of asymmetric flap at a higher speed will give the unwary pilot less time to react, the aeroplane may well be inverted before the pilot realises.

At the lower speed, the pilot has more time to apply aileron and rudder, while retracting/attempting to retract the flaps, to counteract the roll when there’s a sudden asymmetric flap situation

The other situation is asymmetric thrust in a multi engine aeroplane.
This is in one way an opposite situation, where in high speed flight there’s more time, and more control when there’s a loss of thrust on one side.

Rudder power is effective right down to the minimum control speed single engine at MTOW with the CG on the aft limit. It is the rudder that is the primary control against the yaw.
Some aileron may be applied to roll five degrees toward the good engine to reduce the amount of rudder used and improve the limited climb available on one engine.

I nearly became a statistic.
The PIC selected the gear down rather than feathering the propellers and securing the engines when we ran out of fuel in the Seneca I.
“Bad idea that Marv” I said...
We were now destined for the mud in a few seconds so I asked Marv to turn a little left to splat in the mud offshore rather than against the rocks.

At two hundred feet or so the stall warner beeped...
I rationalised this, if we’re into the mud pancake it in...
The props were still windmilling... Bear in mind we are talking seconds here, it takes me many more seconds to type this than a Seneca brick takes to go down.
At one hundred feet the right engine found some fuel :shock:
The Seneca flicked to the left, but I was quick, very quick, and the aerobatic reaction took over.
Foot hard on the right rudder, left hand snapped all the power levers back, right hand added some aileron input, then back and splat.
Windscreen popped out, mud flew up, and we stopped.
Not much more than splatting a loaded 172 with full flaps on a runway.

Of course the lesson is to never rely on someone to do a proper walk around however experienced that person may be.
Of course never ever rely on the fuel gauges.
Practice practice practice your wing drop stall recoveries, and if you can, get some upset training.
T6Harvard, Ibra liked this
#1840727
Flyin'Dutch' wrote:
Asymmetric flap deployments are rare, yet you claim you know a chap who had this several times.

Show us the incident reports.


He landed without incident, and the aircraft went to maintenance as I understand it.

I don't collect reports from everyone I've met who has had something not work quite right on their aircraft.
#1840728
TopCat wrote:
Pilot H wrote:3) Train your muscle memory to always gently unload the stick a little when banking at low altitude and airspeed (eg base to final turn).

Eh? Thus increasing the rate of descent?
Pilot H wrote:Use the trim. It should feel viscerally uncomfortable if you are so out of trim that you have to hold back pressure to maintain airspeed while banking near the ground.

What??? :shock:

You mean trim forward during the base to final turn to make it harder to apply back pressure in the turn? As a protection against pulling back inadvertently?

If that's what you mean, then rubbish. The whole point of the trimmer is to allow you to fly sensitively with small control loads. And you'd then have to remove all that forward trim once you roll out on final, otherwise it will be unpleasantly difficult to flare. Learn to fly properly instead.

If not, then I've misunderstood - please clarify.


Perhaps I didn't explain clearly enough.

One of the biggest killers in the history of aviation, and one which refuses to go away, in is an inadvertent stall/spin at low altitude, usually this is the base to final turn. Often if the turn is overshot, the stall/spin happens when trying to re-align with the runway. But really anytime the aircraft is low and slow, the need to apply back pressure should be something which lights an amber warning in the mind.

I am not advocating anything radical, trimming should be done wings level for a particular airspeed. Then the throttle controls rate of descent. Basic stuff.

All I am saying is that if the aircraft is trimmed for a particular speed on a base leg final in the descent, then as you bank you should be conscious that you are in the corner of the angle-of-attack envelope, and too low to recover if you were to stall/spin. So build in the ability to recognise pulling back on the stick as a threat.

All I am really saying is that banking and back pressure near the ground are two of the ingredients of a classic stall spin (The others are of course a pro spin skid and the coup de grace is often the adverse yaw of a down going aileron)

In a distracted low airspeed low altitude situation, pilots fixate on the ground. If they looked at the slip ball as they were trained there would not be stall spin accidents. But these scenarios take place usually when a pilot has overshot a turn base to final, and uses bank, too much in turn rudder and then back pressure to force the aircraft around at low airspeed and high angle of attack. The aircraft is already yaw/roll coupled and right in the corner of the envelope. Then, while still holding back pressure, the airrcaft is rolled the opposite way, to line up with the runway. The down going aileron adds the final kick.

So, to avoid being in a situation where you are banking and pulling, always trim for the correct base to final speed, and if you feel any back pressure, gently (the word is gently) unload it as you roll into a turn.

Build muscle memory so that it feels just "wrong" to be holding any back pressure in the base to final turn. So one day, when your mind is distracted, and you forget to check the slip ball at low airspeed your muscle memory will remember not to overload the aircraft while trying to save a bad base to final turn (or when getting that impressive photo of your friend's house...)

Alternatively, get upset or aerobatic training. Once you have experienced an aircraft actually and suddenly drop into a spin, you will have renewed respect for the low airspeed/low altitude regime.

In fact scratch all the above. My No 1 Recommendation for stopping becoming a statistic is...

"Spin / Upset training" or even better "Learn some aerobatics"
#1840729
Rob P wrote:
TopCat wrote:... you'd then have to remove all that forward trim once you roll out on final, otherwise it will be unpleasantly difficult to flare.


You have missed the point. Pilot H flies a Cirrus. He never has to flare to land, he just pulls the handle and waits.

Rob P :D


Ah but don't forget I also used to fly a YAK52. We usually landed that the conventional way, as pulling the parachute meant having to bail out old school style :-)
AndyR, Rob P liked this
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