A320 Flap overspeed during retraction?

[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]

It's a problem...

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]

Originally Posted by 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.

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 as long as

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

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.