Why is x-wind an engine limitation?

[PARADOG]

The Airbus A330 manual states the following:

"Wind for takeoff:
‐ Maximum certified crosswind................................................... ......................... 32 kt (gust included)
Note: The maximum certified crosswind value is an Airplane Flight Manual (AFM) limitation. It is an engine limitation."

I understand that the placement of an engine may limit the angle of bank allowable to compensate for x-wind. However, I doubt they mean this by saying "engine limitation", so what factor is actually limiting?

The Max demonstrated x-wind is 40kts, and is stated as not being an AFM tlimitation. I assume this means we know it will go past 32kts, but your insurance ends there. So why is it called an "engine limitation?"

[JABBARA]

PARADOG ,

Any Reference to that statement?

My Manual states (LIM-12 P 1/2)

‐ Maximum demonstrated crosswind................................................... .................40 kt (gust included)
Note: The maximum demonstrated crosswind value is not an Airplane Flight Manual (AFM)
limitation : It is the maximum crosswind condition experienced during the aircraft
certification campaign. Airbus recommends that operators should not intentionally
operate in crosswinds that exceed this value.

[zerozero]

Due to risk of compressor stall.

In order for the fan (and thus the downstream compressors) to work properly, the airflow needs to be smooth and straight.

For the most part, the nacelle, the diffuser (cone) and stators all serve to smooth and direct airflow to the compressor, but in the case of crosswind, low airspeed and high power setting the airflow may be disrupted to the point of causing a compressor stall.

[mixture]

Why would you want to fly a cross greater than 40 anyway ! :E

[foxmoth]

Why would you want to fly a cross greater than 40 anyway !

Possibly to get where you want to be rather than a few hundred miles away:rolleyes:

[mixture]

Thank you for stating the obvious foxmoth. Think you somewhat missed the point. :ugh:

[DeeCee]

Wasn't there an incident at Gatwick when a 747 had both upwind engines stall when it rotated in a strong crosswind?

[foxmoth]

Think you somewhat missed the point.

Yes, missed it and still missing it, Lots of reasons why you might WANT to fly a cross greater than 40 - lots more, sensible reasons, why you should not DO IT.:eek:

[aviatorhi]

Why would you want to fly a cross greater than 40 anyway !

Done it before, I'll do it again.

[CV880]

Is the Xwind TO limitation applicable to all A330 variants or specific to one engine type?
Some years back the RR Trent 700 powered A330 experienced FAN stall in a strong Xwind takeoff with some damage to fan case mounted parts from the resulting pressure pulse. The fix was to revise the EEC software to slow the engine acceleration on take off to allow the aircraft to achieve some forward speed before the engine got into the high power range.

[aviatorhi]

The fix was to revise the EEC software to slow the engine acceleration on take off to allow the aircraft to achieve some forward speed before the engine got into the high power range.

We call it "advancing the power carefully" on older aircraft. Surprised that airmanship has been replaced with software to this extent.

[Old Fella]

aviatorhi, somewhat of a conflict in your comments. You speak of flying in X-winds which exceed the limitation stated and yet question airmanship standards in another.

[lomapaseo]

Wasn't there an incident at Gatwick when a 747 had both upwind engines stall when it rotated in a strong crosswind?

Would you be thinking of Continental having bought a tired old aircraft from Peoples Express

I believe the problem was mostly tired engines (not on the same side) and over pitch after one stalled at rotation due to deterioration of its compressor.

Typically rotation speed (both aircaft and fan) are enough to overcome crosswinds. The takeoff roll however is the pinch point.

[aviatorhi]

Crosswind Limitations on all the aircraft I've ever flown are advisory only, hence I don't consider them, only what I know the pilot/crew is capable of doing. The fact that somebody doesn't want to fly when it's windy is something I find comical. Going past this A330 limitation would be hard/impossible to justify since it seems like a hard limit from what I've read in this thread, but if the fix is/was changing the rate at which the engine is spooling up then the fix is contained in the pilot's hand, don't think changing software should be necessary.

[TonyDavis]

There are a couple of posts here that horrify me, I hope that you 2 are not airline Captains.

Why would you want to even attempt a take off in a crosswind of 40 knots +. Have you no thought of petrfying your passengers? Are you so subjected to commercial pressure that you dont care? Have you considered that if something went wrong, blown tyre or impact with airborne debris, they would hang you out to dry?

The only reasons to operate in those conditions would be a dire emergency (civil war ect.)

If you want to fly like that, go join the military or do it by yourselves.

[aviatorhi]

Yeah, I really worry about how scared boxes get.

[rudderrudderrat]

Hi lomapaseo,

I remember the event very well.
http://www.aaib.gov.uk/cms_resources.cfm?file=/4-1989%20N605PE.pdf

It took over 1 minute from VR before V2 was achieved at a height of 105 ft agl!
22 degs of pitch (with the stick shaker warning on/off) didn't help it climb or accelerate.

[PantLoad]

I remember the wonderful 727. Great airplane. Loved it.

Anyway, if starting the takeoff roll in strong, gusty crosswinds,
the center engine used to cough a bit.... (sometimes)

A lot of guys would line up on the runway....facing into the wind
(crooked on the runway)...to first spool up the center engine.
Once spooled, they would straighten out the plane with the
runway, spool up the pods, and off you go.

Fly safe,

PantLoad

[aviatorhi]

@Pantload

In the 727 my method is to spool up the pods then release the brakes and advance #2 to takeoff power "carefully". Power's always set by the time the speed comes alive.

Funny you mention the "coughing" though; quite entertaining to see the uninitiated go wide eyed when the bird starts shaking.

[overun]

Am l in the wrong place ?

Cross wind limitations only advisory ?

Flight simmers ? Something is going seriously wrong.

[PEI_3721]

Crosswind limits applying to aircraft handling are normally advisory – max demonstrated, unless flight tests show that a limit has been reached, then there should be a crosswind value in the AFM limitations section – max crosswind.
Where an engine has a handling limitation this should be published in the AFM as an engine limitation; any wind condition associated with this becomes a limit for the aircraft.
A note linking the engine and aircraft limits would be appropriate in the aircraft crosswind section.
Prudent operators would use max demonstrated as a maximum crosswind value.

[overun]

Oh dear.

You reigned in the ads and forgot the divots.

[aviatorhi]

According to: National Aerospace Laboratory NLR

According to the Flight Test Guide there are two possibilities on how to note crosswinds in the Aircraft Flight Manual AFM.1 If the demonstrated crosswind is not considered to be a limiting value for aircraft handling characteristics, this demonstrated value can be placed as information in the AFM. Higher crosswinds are then allowed when the applicable operational requirements and the airline specification allow it. For instance, the AFM of the B737-400 states the following on crosswind “The maximum demonstrated crosswind component for takeoff and landing is 35 knots reported wind at 10 meter height. This component is not considered to be limiting on a dry runway with all engines operating”.

Here ya go, ya divot.

[Denti]

Correct, demonstrated crosswind limits are advisory only, however if something goes wrong when above those limits the pilot trying to be a test pilot will be fully and solely responsible for the outcome. However even in olden manuals there were usually real limitations for stuff like autoland / CAT III.

However nowadays most manuals contain fixed crosswind limits which indeed are a limitation and not an advisory. QAR-Analysis will makes sure that busting those limits will be found out and depending on the rules in the relevant country/company will lead to a nice chat in the safety department, retraining or suspension.

[cwatters]

http://www.skybrary.aero/index.php/A320,_Hamburg_Germany,_2008_(HF_LOC_WX_AW)

Recommendation No.: 15/2009

To the Luftfahrt-Bundesamt (German Civil Aviation Authority) that:

The Luftfahrt-Bundesamt should ensure that maximum crosswind take-off and landing speeds are set for German Air Operators. Within the context of flight operations management, all air operators should examine the handbooks provided by different aircraft manufacturers for different aircraft types and study how the handbook wording maximum crosswind demonstrated is interpreted and acted upon. When indicated, an instruction should be issued based on EU-OPS 1.015 to require that maximum crosswind values be set for crosswind take-offs and landings.