DR-400 in AN-2 vortex

Ted wrote:

AFAIK “maneuvering speed” only considers the static deflection of a control surface, it does not consider any momentum or hysteresis.

That is exactly the point. It took the the AA587 accident to make the airliner training industry aware of that.

greg_mp wrote:

I remember of a A310, probably this one:
https://en.wikipedia.org/wiki/Air_Transat_Flight_961
That results in only a rudder detachment, but zas able to land safely.
And this one which a A300:
https://en.wikipedia.org/wiki/American_Airlines_Flight_587
that finally crashed.

The AA accident, not the Air Transat. The Air Transat accident wasn’t due to manoeuvring.

Airborne_Again wrote:

I can only remember one case where someone overloaded an airline using the rudder. Can’t recall if it was an Airbus, though. The cause was not simply a large rudder deflection but repeated large and rapidly alternating rudder deflections.

I remember of a A310, probably this one:
https://en.wikipedia.org/wiki/Air_Transat_Flight_961
That results in only a rudder detachment, but zas able to land safely.
And this one which a A300:
https://en.wikipedia.org/wiki/American_Airlines_Flight_587
that finally crashed.

Here’s the direct link to the video for those that don’t use Macromedia / Adobe Flash: https://www.bfu-web.de/videos/BFU_V180_EN.mp4

Peter wrote:

I don’t get that because surely the ailerons still have the same relative airflow over them.

Perhaps its in the german to english translation. If the vortex covers the wingspan, the turning moment is the greatest, for the same reason the ailerons are placed where they are.

Peter wrote:

I wonder if using the rudder also would help in such a case?

huv wrote:

“maneuvering speed” regarding repeated control surface deflections.

AFAIK “maneuvering speed” only considers the static deflection of a control surface, it does not consider any momentum or hysteresis.

Airborne_Again wrote:

The cause was not simply a large rudder deflection but repeated large and rapidly alternating rudder deflections.

Yes, and although primarily the copilot was blamed for the accident, and still is in the public opinion, the root cause was found to be a critical and long-lasting lack of communication between aircraft designers and the training industry about the interpretation of “maneuvering speed” regarding repeated control surface deflections. It was not implied that the type of aircraft (it was an Airbus A300) had any significance in the accident, except, perhaps, that it had relatively light rudder forces.

Pardon the thread drift.

Original thread from 2015:

https://www.euroga.org/forums/hangar-talk/4350-dr-400-in-an-2-vortex#post_71976

Worth reminding. Especially since even at a controlled airport you will not be warned against wake turbulence from an AN-2 because it is technically in the “Light” category (below 7000 kg).

[ threads merged ]

Peter wrote:

Best to not do that on an Airbus though… somebody broke one of them doing that.

I can only remember one case where someone overloaded an airline using the rudder. Can’t recall if it was an Airbus, though. The cause was not simply a large rudder deflection but repeated large and rapidly alternating rudder deflections.

Good video – many thanks for posting it, and welcome to EuroGA @mkfly

One big point they are making is that when the vortex diameter is big enough to cover the wingspan of the affected plane, its ailerons become ineffective. I don’t get that because surely the ailerons still have the same relative airflow over them. It is just that they don’t have enough power to overcome the vortex – in the same way as a plane may not have enough climb capability to overcome a downdraught.

I wonder if using the rudder also would help in such a case? Best to not do that on an Airbus though… somebody broke one of them doing that.

Their server is slow and one has to pause it every so often to let the download catch up.

Video on wake vortices from the German air investigators (now EN language)

Hi All, long-time reader but first time poster here.

The following video on wake vortices (the An-2 / DR-400 vortex accident) has been referenced on here a few times over the years as “German only”. It seems to now be available with an English voice-over so may be worth another look.

https://www.bfu-web.de/EN/Service/V180-Video-EN/V180-Video-EN_node.html

Cheers,
mkfly