Max. Demonstrated Crosswind Compoent

[Vortilon]

While we all recognize it is not a published limitation, if you had an incident while exceeding this "manufacturer's advisory" you could certainly be held responsible for disregarding safe & accepted practices and disregarding information from the manufacturer. Of course as a PIC you are always responsible for everything and you always have to balance risk but sometimes its good to put yourself on the business end of an inquiry board and pretend you are explaining your logic to a FAA Inspecor & their lawyers. Maybe there you'll find your answer.

Be careful out there!

 

[standaman]

I agree with Vortilon. Any lawyer worth a salt would paint you as exceeding a manufacturers recomendation. The FAA could always come after you for careless and reckless operations from what I know is very very broad.

 

[Lead Sled]

I agree with Vortilon. Any lawyer worth a salt would paint you as exceeding a manufacturers recomendation. The FAA could always come after you for careless and reckless operations from what I know is very very broad.

I disagree. Remember, it is not a limitation or a recomendation. It is simply the amount of crosswind that was demonstrated on "crosswind landings day" when they were flying the certification flights. Like I said in my first post, it is basically a weather report - we now know how hard the wind was blowing on that particular day.

Just for grins, I pulled out my G-100, Astra SPX and Astra FlightSafety Manuals. Guess what? There is no mention of demonstrated crosswind in the AFM. My G-200 manuals are packed away, but I would venture a guess that there is no mention of it there either. In fact, I don't remember a number even being mentioned in the Lears, but is't been 8 years since I've flown one. I guess that this means that we can't land in a crosswind with out being in danger of incurring the wrath of the FAA.

Lead Sled

 

[bugchaser]

All I know is that if we didn't fly when the wind exceeded the max demonstrated x-wind, we would never get anything done. When it gets up to about 40kts we start to think about it.

 

[Jmmccutc]

the worst is a statement in my school's SOP's, stating that, "...no student shall take off or land when the X-wind exceede that demonstrated by the manufacturer..." seems like we never get anything done if there is so much as a light breeze...Crewdawg, am i right?

 

[igneousy2]

I agree with Vortilon. Any lawyer worth a salt would paint you as exceeding a manufacturers recomendation. The FAA could always come after you for careless and reckless operations from what I know is very very broad.

If you end up in the weeds on the side of the runway, it doesn't matter what the wind was or what the x-wind component of the plane was you are toast. You're either wreckless if you landed with winds in excess of the x-wind component or you're an incompotent pilot if you could not handle the plane in a x-wind below the max-demonstrated.

Either way...you loose.

Later

 

[spngbobsqrpilot]

Max Demonstrated X-Wind

The "limitation" (not actually a limit) is derived by a function of 20% of the stall speed of the aircraft being certified. (Can't remember if its Vso or Vs. as it has been a few years since I have taught primary students X-wind landings.

The FARs (Part 25, I believe) require the aircraft being certified to be capable of controllabilty with a direct x-wind component equalling that speed above. That is all. This is the Maximum demonstrated X-wind and the actual wind on the date of test flight may have been greater, however, the number in the manual is the demonstrated capability to show certification according to Part 25.

A manufacturer is not required to show the actual crosswind encountered during the flight testing phase (and may be opening itself up to lawsuits if a number is placed there showing what a qualified test pilot can do rather than a novice can if the novice attempts to use that number as a personal limitation) and that is why, with experience, it is possible to land your C-152 in crosswinds of 30 kts. No, the manufacturer won't tell you this in your manual because it was not required for the manufacturer to do so.

 

[midlifeflyer]

The "limitation" (not actually a limit) is derived by a function of 20% of the stall speed of the aircraft being certified. (Can't remember if its Vso or Vs. as it has been a few years since I have taught primary students X-wind landings.

It's Vs0.

Which Part depends on the aircraft certification. For us little guys, it's in Part 23

==============================
§ 23.233 Directional stability and control.
(a) A 90 degree cross-component of wind velocity, demonstrated to be safe for taxiing, takeoff, and landing must be established and must be not less than 0.2 VS0.
==============================
But that only establishes a minimum certification safety standard. It doesn't mean that's the number that's used for the published demonstrated crosswind component. After all, the company gets a competitive advantage by showing how much "better" it's airplanes are, without going overboard.

For example, Vs0 in a new 172 is 47 KCAS; in a new Archer III it's 45, but neither manufacturer publishes 9.4 or 9 KTS as the max demonstrated crosswind component. In fact, Piper, with the lower Vs publishes a higher demonstrated crosswind number (17 KTS) than Cessna (15 KTS).

 

[GVFlyer]

X winds

When we were doing GV developmental test and certification we dedicated a test article to crosswind testing for several weeks. Part 25 calls for a minimum of 20 knots, but demonstrated crosswind does not have to exceed 25 knots. We were flying all over the country looking for crosswinds. When we found 28 knots we thought that was good enough.

For T category aircraft most test programs are around 18 months long and take about 1500 to 1800 hours to complete. Note I said most - several exceptions come to mind. We do have a schedule to maintain as someone suggested, so when we get a good number we move on.

The exception was the Air Force C-20B (G-III). They wanted a greater cross wind capability so they paid Gulfstream to retest the jet and come up with a procedure to accomodate better numbers. We were able to give them 35 knots with 8 degrees wing down and up to 4 degrees crab at touchdown.

In my view, when you exceed the demonstrated crosswind for your aircraft you are venturing into the realm of the experimental test pilot. We do a safety review board prior to such testing, limit the occupants to mission essential crew and don't carry passengers.

GV

 

[Muddauber]

Now that makes sense...

 

[standaman]

I agree with gvflyer. We should not debate the merits of limitation versus suggestion versus are we really breaking the rules in the first place. The question should be is it at all smart under any circumstance. Smarter people than myself developed the max crosswind component. Have I exceeded it, probably, should I exceed it, I don't think so. As a flight instructor should I teach my students to explore these flight regions which manufacturers test pilots have not even gone. My answer to this is no. It sets a bad precedent for students wether it is legally okay or not.