Maximum demonstrated crosswind component
 

Could anyone point me to the certification requirements (part 23) that explain how this 'maximum demonstrated crosswind component' is derived?

Is this a legal 'limitation' that must be observed? Is it a demonstrated strenght test of the landing gear?

Thanks, and good luck!

The requirement, such as it exists, is in 23.1585(a)(2). As to means of compliance, it should be referenced against the paragraph no. in FAA's AC23-8 but I don't have a copy to hand to confirm that (there's only so many documents one can keep copies of at home!).

If you haven't got a copy, but do have a fast connection or the patience, you can download 23-8 at http://www2.airweb.faa.gov/Regulator...Highlight=23-8

The requirement is entirely a handling requirement - there are no additional structural requirements on part 23 aeroplanes which are a function of crosswind limit. It is also given as a demonstrated limit, it is not a fixed operational requirement - although many operators not unreasonably elect to make it so.

G

Genghis,
Talking of crosswinds...can you tell me on what basis (vis-a-vis x-wind) the Vmcg is calculated in CAA regs. Does this differ for the US and if an A320 were operating in the US, for example, do AI change the performance or just accept the appropriate degradation by using x-wind figures.
I ask because a long time ago I was involved with the L1011-500. If we were operating off short strips, under CAA regs we could de-rate the engines to 22B thrust and because of the reduced Vmcg thereby lift a lot more weight from the runway. If memory serves some 10T more! The US registered -500s had different Vmcg figures and did not suffer such large problems, but it was then decided to operate to UK regs.
Our 321s can be Vmcg limited and I was wondering if there had been any changes since the 80s.
Thanks a lot.:p

UK - 7kt X/W
US - nil wind

Try Mutt .. he plays with derates and Vmcg/V1 sensitivities ...

Not my territory I'm afraid, I'm part 23 or smaller, with the occasional divergence into fast jets.

G

The maximum demonstrated crosswind component is not a legal limit, it’s more of a guideline.

To the best of my recollection I think the aircraft manufactures use 20% of Vso or Vs1 to calculate maximum crosswind, this generally produces a low number, for example a Cessna 150 max X-wind is about 10-12 mph as I recall, this is very low if you use it as a hard and fast limitation. Pilot experience, aircraft equipment, airport runway conditions should dictate personal limits.

idg,

BCARs used to demand that Vmcg was demonstrated in a 7 knot adverse crosswind, that being statistically the worst that you might reasonably expect to get on the rare occasion that an engine failed at the critical moment. As part of the process of harmonising national regulations to create JARs the CAA was reluctantly forced to accept zero crosswind Vmcg so now the US and European regs are the same in this respect. A lot of chicanery used to go on with some company,s test pilots loading the nosewheel to create more damping of the swing due to engine failure, but the certification authorities are pretty wise to this now and demand that the test is done with minimal weight on the nosewheel.

To gain a C of A the large aircraft manufacturer has to demonstrate crosswind TO and Landing in a crosswind of 0.2 Vs, except that he must demonstrate at least 20 knots but does not have to demonstrate more than 25 knots. Most manufacturers try to test the most they can, but the wind doesn't always blow when you want it and they cannot hold up the certification programme while they wait for it to do so. The max demonstrated crosswind is not a limit necessarily, but anything above that is to be treated with caution. Airlines will differ in their policy on this. Also, some manufacturers will quote a max crosswind tested in the simulator. However, this also needs to be treated with caution because no simulator is better than the data fed into it and it is doubtful whether, for example, the roll power due to aileron is acurately modelled for all the levels of ground effect which might be experienced in a crosswind landing. Personally I think that a hard limit should be set at the max crosswind demonstrate by the manufacturer, but I should think any proposal along those lines would result in some pretty loud squeals from industry.

Guys,
Thanks for the replies. We do in fact use the maufacturers demonstrated crosswind figures as our company limit but I too think it's appropriate. Interesting to note that the JARs only use still air Vmcg figures. I presume that all AI a/c are certificated thus. Would the flight manual put me straight on this?
Cheers.
:rolleyes: