A320 Flap overspeed during retraction?

[FlywithPark]

In case of flap retraction at 'S' spd during take off, sometimes spd increase over 230kts(flap 1 limit spd) during flap retraction.
Can we consider we committed flap overspeed in this case? We can encounter this situation several times especially in heavy weight takeoff situation.
How's your thought?
In my company, this is big issue now because by this case a pilot failed his checkride transitioning to captain.

[Natstrackalpha]

So you are saying that "S" speed in your case is too fast for Flap Retraction?
Well until you hear further do not retract below "S" speed especially - if heavy weight.

[ironbutt57]

think what he's saying is the "s" speed is so close to vfe, that during acceleration and flap retraction, the slats don't quite get out of the way before the airplane hits 230 KTS...simple solution is to speed select 230 kts on the MCP..

[skinz]

Just wondering, thought the A320 has a flap auto retract feature when the speed reaches 215 Kts leaving only the slats extended. Hence the only device that would overspeed is the slats. Puzzled..

[Valmont]

Airbus says: PNF selects the FLAPS lever position and replies " FLAPS ONE"after checking the blue number on the ECAM flaps indicator to confirm the correct selection has been made.

To my mind this is a non event if the flaps position indicator went blue before speed reached VFE.

Hence the VMO/MMO changes to the next relevant one as soon as the indicator colours in blue.

Furthermore, your coworker would get an overspeed.
If he did not... Well he can complain.

[BOAC]

simple solution is to speed select 230 kts on the MCP.. - you have NO idea what sleepless nights you will be causing our 'children', do you? MCP?? Whatever next?:)

Seriously, I recall early 733/4 'company mandated' VNAV accel days we sometimes programmed 230 at 3000' into the FMC and deleted or went MCP when clean.

[A4]

Heavy weight, allow the aircraft to accelerate normally towards 'S' speed which will possibly result in auto-flap retraction i.e. from 1+F to 1 (slats only). Approaching Green Dot, select flap 0 and MONITOR acceleration towards 230 compared to Slat retract speed.

If in doubt, PULL SPD at, say, 225-228 knots, when the slats are in, MANAGE SPD, no-overspeed. Job done.

[vilas]

flywithPark
S speed for 78T TOW is 211KTS. So there is good 19KTS to VFE, lesser TOW will have even higher margin. So since you are aware that overspeed may occur when you see slat auto retraction at 210kt if you also select flap zero you should not have a problem. A4 suggestion is not good because green dot speed beyond 72T is higher than 230KTS and will lead to overspeed.Offcourse flying select 220 or so is always possible.

[Luckyguy]

Vilas....
the slats do not auto retract at 210 kts, the flaps do !
With an S speed higher than 210kts, the flap lever should be moved to the 0 position at S speed assuming the aircraft is accelerating. This means that the flaps will already be travelling, followed by the slats commanded by the flap lever position.
The FCTM makes no mention of SPD select to control the IAS at or below FLAP limit speed of 230Kts. It is also going to be pretty close to GD, however, there is also nothing to say that you can't fly below GD speed withouit selecting flap 1. Airbus just don't recommend it !
In turbulent conditions, it may be impossible to control the speed at or below 230 Kts before the slats have completely retracted. It is transient in most cases and short term.
What would the check Captain prefer.... flying below green dot clean or the slats retracting the final few degrees with a decreasing aerodynamic load passing 230Kts.
:confused:

[vilas]

Luckyguy
Sorry I wrote slat by mistake offcourse it is flaps retraction. But i don't understand where does green dot come in while retracting slat. As long as you are accelerating at S speed you retract to flap zero. You don't wait for GD to retract slats/flaps. As far as flying below green dot is another issue. Airbus permits flying below GD. All speeds upto VLS are flyable. Only thing changes is the bank angle at which high angle of attack protection will be triggered. Below GD it is reduced 40 degrees of bank.

[Luckyguy]

Green dot only comes into it as a coincident speed at that weight. If you control SPD from the FCU to below GD, whilst trying to avoid a flap\slat overspeed (which may only be a very small number of knots), you quite possibly end up clean below GD and maintaining that SPD as it's selected. Calm conditions at that weight and pulling SPD 230Kts, the auotpilot or ace pilot doing a fine job and all is well. That's all I was trying to say.
As I said, you can fly a SPD below GD clean, Mr Airbus, as told to me by a nice man at TLS, don't recommend it for the obvious reasons !

Cheers

[gAMbl3]

How about preselecting 215 kts in Perf CLB page and once flaps+slats retracted confirmed on E/WD, go managed speed?

[A4]

Vilas, don't forget that 'F' and 'S' speeds are the MINIMUM speeds that flap should be retracted at. With a positive speed trend there is nothing wrong with retracting at S+10 knots - you're giving yourself a buffer and when you move the lever you're going to be almost at GD speed. This is not so critical on lower weight departures but at higher weight takeoffs the cleanup needs to be more "efficient" in terms if energy maintenance and using speed TREND effectively.

Alpha lock will only prevent the SLATS from retracting if the AoA is greater than the limit at the moment the lever is moved. Once the SLATS are retracting the will keep going. So only select FLAP 0 with a nice positive speed trend and a buffer - if hand flying it is easy to "adjust" the speed trend line with sidestick to prevent an overspeed - it's called aviating :)

To clarify my earlier post, selecting say 225-228 knots is a momentary "fix" whilst the last few seconds of SLAT retraction occur - your hand wouldn't even come off the FCU SPD knob. Thrust will not reduce because you will be in THR CLB and as soon as you're clean, PUSH for MANAGED speed the attitude will reduce to facilitate acceleration to 250knots / climb speed.

@gAMbl3 - because at very high weights you could end being clean well below GD. Additionally the pitch to maintain 215 may well put you above the AoA threshold for Alpha Lock in turbulent conditions. Keep the energy/speed/trend positive, watch the SLATS as they retract on the E/WD, intervene / manage as required.......it's what we're paid to do.....fly the aircraft safely within its limits.

[Nightstop]

Whereas VFE on the PFD is displayed according to the position of the flaps lever, the audio/ECAM warning is triggered separately by the actual position of the flaps and slats. If the slats are still in transit above 230 , the aural/ECAM warning will trigger until the system has registered that they are retracted fully.

When using the autoflap retract procedure, the buffer between a selected speed of 220kts and VFE CONF 1 (230) can sometimes not be sufficient if there is a delay after engaging managed speed before CONF 0 is selected. So, select CONF 0 & pause before pushing managed speed (250).

[FlywithPark]

Thank you guys for your kind replies.
The point what we try to be clear is whether he committed flap overspd even though he engage flap 0 at 's' spd.
At that situation, he had to level off at 3000' he ordered to f/o to set flaps '0' at just passing s spd during acceleration.(it was around 205kts)
During flap transit, the checker saw spd trend passing 230 kts even the flap indication still showing blue.(after QAR review we found out spd was 235kts when actually flap finished its movement to 0)
Anyway.. He ordered "flaps 0" just passing s spd. Does he still have to be blamed because he didn't pull spd below 230kts?

[vilas]

Lucky guy and A4
Don't worry about that nice man. There is an Airbus presentation on this subject. What I stated is from that. Any speed above Vls is safe but if you fly at Vls in turbulence for long time it can trigger alfa floor during maneuvring. 230kts is flap1 lowering speed. S is the speed at which with +ve trend you retract. I have not said anything about alfa lock I am talking about alpfa floor. If you fly below GD it may trigger at 40 degrees of bank. On AP AC does not bank that much anyway. Have buffer by all means if you have but surely don't bust flaps for that. As long as you retract at S speed accelerating going clean below green dot is not forbidden.

[vilas]

FlywithPark
Only now you stated the real problem that is he had to level off. Climbing acceleration is not a problem. Whenever you don't want acceleration the remedy is to pull speed and then solve the problem. Since he didn't do that it is overspeed. It can happen only at high weights in level flight. Normal weights the higher margin will take care. Bad luck it was a check ride.

[MD83FO]

I thought the airplane would pitch to not exceed Vfe as seen on the simulator.

[A4]

MD,

The autothrust will protect against overspeed if configured i.e. limit speed to VFE Next.......but when you select FLAP 0, there is no VFE Next so the autothrust will keep the thrust on to target 250 knots and,if level, easily out accelerate the SLAT retract with resulting overspeed.

[vilas]

FlywithPark, A4 and Luckyguy
What I could copy from Airbus document is below.
In CONF1+F:S speed could be close to VFE
IfFLAPS 0 selected above Flap auto retraction speed (210 Kts on this example):

PossibleVFE OVERSPEED warning if rapid aircraft acceleration
NoVFE structural limit exceedance.

Do not delay FLAPS 0 selection above S speed =>prevents possible momentary VFE OVERSPEED warning

Flap maneuvering speeds are not limitations:

Itis safe to fly between VLS and VMAX (VMO, VLE, VFE) :

The requiredaerodynamic margin is properly ensured
This is from Airbus. I hope this answers all doubts.

[rudderrudderrat]

PossibleVFE OVERSPEED warning if rapid aircraft acceleration
I wonder why Airbus pilots never think of retarding the TLs, below the climb gate to some sensible power setting, to reduce the rate of acceleration until the aircraft is clean.

Is it simply due to the design of non moving TLs when Auto Thrust is engaged, or a reluctance to take manual control?

[PantLoad]

Yes, at heavy weights, it's a problem. On the 93T version of the
321s, the Vfe is 235, instead of 230.

According to the FCTM, assuming you are careful in not gaining
too much speed while going from Flaps1 to Flaps 0, and assuming
you're really heavy...like 89T....you may encounter Alpha Lock...
and this is to be considered "normal"...."Normal"in the sense that
it is somewhat expected....and is NOT to be considered your fault.

Exceeding Vfe is not good....but, in the case you described, I'd
say screw it....if you get into trouble with the chief pilot, just
nicely explain what happened.... While five knot overspeed is,
technically, a limitation violation, it is not the end of the world.
If five knots over will cause damage to the slats, then it woulc
be better to buy a Boeing.

Don't sweat it...

It happened to me one morning. We were at max 89T for
takeoff (or slightly under)....I was flying....called for FLAPS
ZERO at "S"speed....we were in moderate turbulence...and
we hit 230 knots without the slats being fully retracted. I
guestimate we were at about 232 or 233 when the slats
were completely retracted. I couldn't have cared less....
Not my problem.... BTW, the autopilot was on at the time, too.

So, blame it on the autopilot....

[WhyByFlier]

Can you perhaps make use of the Alpha Lock function?

From FCTM NO-050 P 7/10:

THE ALPHA LOCK FUNCTION The slats alpha/speed lock function will prevent slat retraction at high AOA or low speed at the moment the flap lever is moved from Flaps 1 to Flaps 0. "A. LOCK" pulses above the E/WD Slat indication. The inhibition is removed and the slats retract when both alpha and speed fall within normal values. This is a normal situation for take-off at heavy weight. If Alpha lock function is triggered, the crew will continue the scheduled acceleration, allowing further slats retraction.


It happened to me one morning. We were at max 89T for
takeoff (or slightly under)....I was flying....called for FLAPS
ZERO at "S"speed....we were in moderate turbulence...and
we hit 230 knots without the slats being fully retracted. I
guestimate we were at about 232 or 233 when the slats
were completely retracted. I couldn't have cared less....
Not my problem.... BTW, the autopilot was on at the time, too.

Out of interest, as the pilot, whose problem was it? If it doesn't do what you want then take over. Too much to expect you to disconnect and raise the nose? Or follow the written procedure?

FCTM SI-010 P 8/16:

For takeoff in high turbulence, the flight crew must wait for the target speed +20kt (limited to VFE-5) before retracting the slats/flaps (e.g. the flight crew must wait for F+20kt before setting Flaps 1)

I wonder why Airbus pilots never think of retarding the TLs, below the climb gate to some sensible power setting, to reduce the rate of acceleration until the aircraft is clean.


Or raise the nose.

[sabenaboy]

In case of flap retraction at 'S' spd during take off, sometimes spd increase over 230kts(flap 1 limit spd) during flap retraction.
Can we consider we committed flap overspeed in this case? We can encounter this situation several times especially in heavy weight takeoff situation.
How's your thought?
In my company, this is big issue now because by this case a pilot failed his checkride transitioning to captain.

VFE and VFE NEXT are displayed on the PFD according to the FLAPS’ lever position. OVERSPEED warning and VLS, displayed on the PFD, are computed according to the actual flaps/slats position. (source of this info: qrh, landing with slats or flaps jammed)

To me this means that as long as there was no overspeed WARNING, there was no overspeed condition. When you retract the flaps from 1+F to up, you see the Vne speed not quickly jumping up, but rapidly move to 350 kts. To me this means that you never were in overspeed if you did not enter the red tape (even if you exceeded 230 kt while the flaps indication was still blue)

Anyway, if apart from this "imperfection" the captain in training displayed good airmanship and performed well, I would consider "flunking" him very harsh. Could it be he wasn't performing well overall and this event was just one of the excuses used to justify him being stopped from upgrading?

edited for spelling

[BlackandBrown]

To follow up - in the very worst case scenario on the A320 at MTOW (78 tonnes) S speed is 211 kts ( QRH FPE-SPD-1). Follow the FCTM procedure - it's prescriptive in this scenario.

[WhyByFlier]

S speed on the 320 at MTOW is 211 kts ( QRH FPE-SPD-1 ), VFE as has been mentioned several times is 230 kts - follow the FCTM procedure, use it to justify your actions and you can't really go wrong.

[PantLoad]

Not my problem as long as I've followed the SOP.....

The issue becomes relevant with the 321 (not the 320) when
the actual take off weight is close to 89T (for an 89T 321).
The problem is that the minimum speed and the maximum speed
are close. So, if you retract (from Flaps 1 to Flaps Zero) at
"S" speed (SOP), with pitch and subsequent acceleration
as typical, the slats become fully retracted extremely close
to 230 KIAS. (We're talking just a few knots....)

If you don't accelerate quite quickly enough, you could get
ALPHA LOCK. If you accelerate very slightly too quickly,
you get an overspeed by a few knots. Even if the pilot is
"Bob Hoover" quality, in turbulence, under the above-stated
conditions, it's possible to get either ALPHA LOCK or
overspeed. (Again, if you do it just right, you'll get the
slats completely retracted within only a few knots of the
230 maximum.)

Again, when Airbus went to 93T on the 321, they increased
the speed from 230 to 235. They had to....

[misd-agin]

What about pulling the nose up? Worked for over 100 years.

It's a issue to pay attention to on heavy 767 departures. Normal climb pitch attitude would result in potential overspeed as plane accelerated due to amount of time to retract flaps 5 to flaps 1.

"Flaps 1" works best with a pitch increase of 1-2 degrees. Pitch increase while accelerating to clean up is not typical. Stabilize speed increase to avoid overspeed and reduce pitch attitude AFTER overspeed potential has been nullified.

[WhyByFlier]

If you just follow the procedure in FCTM it works!

[PantLoad]

Pull the nose up, it works...

Yes, and go into ALPHA LOCK because you're too slow
for a clean wing....

Yes, follow the SOP and you'll be OK.....

[WhyByFlier]

ALPHA LOCK is a normal thing at very high mass. See my post above. Use the procedure to cover your ar$e. Raising the nose will work too.

[vilas]

The case at hand had to level off while accelerating that was the problem. This is unusual case you can go select speed 220 or so retract to flaps zero when auto retraction takes place then go managed again. in climbing acceleration there is not much problem refer to my post no.20. What I have stated there is from Director of A320/A330/A340 Flight Operations standards

[qwsa]

Just make the speed preselection on the climb page in the FMGS,sey 225 kt when you are heavy prior to your departure.

[BTV]

As Vilas said,
It is safe to fly between VLS and VMAX (VMO, VLE, VFE).

For checkride, he should've done something to stay in the safer side of airspeed. As far as I know, flap lever, PFD indications cannot guarantee it, especially in Airbus. That is airbus. You can have an ECAM warning for overspeed even when the lever is at 0, which calls mechanics.

[redfly]

So let's think about something else during take off and flap retraction. I wonder how to fly a speedlimited departure in the right way assuming I'm sitting in a heavy A320:
Presume there are 210kts speed limit at maximum during turns in your departure. Let's say our A320 has a GW of 66t leading to a green dot speed of 217kts and s-speed of 195kts. We take off with conf 1+F. If we clean up now according our SOP's without planning ahead at s-speed we soon will be trapped since now our green dot is above 210kts speed limit during departure...

I thought about flying it with 210kts preselected speed and fly it over the s-speed with conf 1+F until we're out of speed limited departure. What would happen if due to gusty conditions the speed increases to above 210kts? The flaps would retract due to auto retraction funtion, right? And conf 1 (slats only) leads to a higher green dot speed than conf 1+F! But I cannot determine what value that is, right? Hence a better choice is to preselect 205kts for a better speed marging during departure and keep conf 1+F, right?

I would like to know your thoughts about that issue. How would you fly such a departue?

Thank you for your input!

[MD83FO]

There is no green dot speed for flaps, S speed remains at 195 in conf 1 and you are protected by Vls just like on approach so you can stay at 210k selected.
In fact i would allow the flaps to auto retract and then press EXP to maintain S speed.

[CaptainProp]

In fact i would allow the flaps to auto retract and then press EXP to maintain S speed.

I would not recommend that, you will potentially trigger the TCAS and you are also running the risk of busting low level/altitude climb restrictions.

As mentioned before by a couple of people:

It is safe to fly between VLS and VMAX (VMO, VLE, VFE).

Select Flap 0 below S speed while accelerating, I can't see anything wrong with this technique.

[vilas]

redfly and MD83FO
One year back I answered this question in my post no.20.which was from Airbus itself. Please read that again. Redfly GD speed does not change with flap setting. Also all speeds above VLS cans be flown. So you are trying to develop procedures from a basic premise that is incorrect. There is simply no need to do anything different.

[redfly]

Gentlemen, thanks for your response.
Now your procedures tells you that it is not allowed to fly clean below green dot speed. How do you fix that problem now?

[vilas]

redfly
It is permitted to fly below GD. From Airbus "Flap manoeuvring speeds are not limitations. It is safe to fly between VLS and Vmax(VMO, VLE, VFE). The required aerodynamic margin is properly ensured." I am reproducing from my post NO.20 which is also from Airbus.
"Possible VFE OVERSPEED warning if rapid aircraft acceleration. No VFE structural limit exceedance". So it is a nonissue.

[Natstrackalpha]

"How about preselecting 215 kts in Perf CLB page and once flaps+slats retracted confirmed on E/WD, go managed speed? "


A tad Magenta.


Also, would you not then be stuck at 215 kts for the climb? - well, at least until > FL100, if in managed then I assume it would default to - -whatever your managed speed for the climb was - say, 270.

[C_Star]

Now your procedures tells you that it is not allowed to fly clean below green dot speed. How do you fix that problem now?


If you can't/don't want fly clean below GD, keep her at 1+F. If you feel that at 210kt you don't have enough margin to Vfe, select 200kt for the turn...

Keep it simple! :ok:

[sabenaboy]

The case of temporary overspeed aural warning during slats / flaps retraction after a heavy-weight take-off
In the particular case of a heavyweight take-off, the risk of a temporary overspeed aural warning is increased. Indeed, in this configuration, S speed is quite close to VFE CONF 1+F because the aircraft weight is higher and the lift needed to climb is higher too. Therefore the slats need to remain extended for longer. As a result, the crew will order flaps retraction at a speed that might be higher than the Flaps Auto-retraction speed.
In that case, should the acceleration of the airplane be rapid, a VFE aural warning may momentarily trigger.
This logic is as per design and structural limits are not encountered.
For example, an A320 at a Take-Off Weight (TOW) of 76T, S speed of 205 kts, the pilot will order flaps retraction most probably at or slightly above
210 kts, which is precisely the Flaps Auto-retraction speed. Once the slats / flaps control lever is in the retracted position, the VFEred and black strip is no longer displayed on the PFD speed scale. If the airplane accelerates rapidly, then the airspeed may catch up the actual instantaneous VFE momentarily, which will trigger the VFE aural warning.
Again, this logic is as per design and structural limits are not encountered.

Source: Airbus Safety First Magazine 20 (http://www.beca.be/magazines/safetyfirst/SafetyFirst-20.pdf). Page 12

[Metro man]

Be careful if departing at high weights with an MEL item indicating flaps/slats slow. Under normal circumstances the lift devices would retract before you accelerated through their limiting speeds, however if clean speed is high due to an increase in weight its quite easy to be passing 215/230kts while they're still on the way in. In this situation select minimum clean speed and wait until retraction is completed before managing the speed.

If departing in the mid 70t range I brief to expect a possible auto retract of the flaps as it only takes a little turbulence or even a turn to trigger it. Flaps go up and barbers pole moves up no drama, though it is recorded by FDM. The reason is obvious in the case of a high weight T/O though at lower weights you may be asked for an explanation.

Auto retract is the reason some MEL items prohibit T/O in 1+F incase it gets triggered at an inappropriate time. There is no auto retract in CONFIG 2 or 3.

[lhero]

It's also good to note, that even without FLAPS/SLATS SLOW - indication, they don't always retract at the same rate. I've witnessed almost twice as slow retraction of flaps on at least one aircraft one day, during several sectors. The difference was there also when retracting on the ground (I timed it for comparison to other aircraft).

[Natstrackalpha]

I think they were being picky. Sometimes they want you to do a F3 departure, in the box, just to see if you get all the flaps up in time to avoid a flap limiting . . . thing.

[Denti]

A tad Magenta.


Also, would you not then be stuck at 215 kts for the climb? - well, at least until > FL100, if in managed then I assume it would default to - -whatever your managed speed for the climb was - say, 270.

Nope, preselected speeds will change the mode into selected upon activation of the relevant flight phase with the preselected speed in the speed window as target. Simply push the button and you are back in the normal managed mode with normal speeds.

[bond2002]

This is mentioned in one of the safety first magazine issued by Airbus
If it helps

On A300/A310, A320 and A330/ A340 Families,
• The VFE value displayed on the PFD
is based on the slats / flaps con- trol lever position and it moves by one step as soon as this lever is moved.
• The overspeed aural warning trig- gering threshold varies according to the actual aircraft configuration, i.e. the slats / flaps surfaces real time position.
Therefore, during slats / flaps tran- sition, the dynamic acceleration of the airplane may lead to a temporary OVERSPEED WARNING even if the current speed is out of the red and black strip displayed on the PFD. In this situation, there are neither opera- tional consequences nor safety issues.[