gestrich1311

I wouldn't consider the student to be a passenger however that section gives specific information on flight instruction. If that part were not there, I would say it is ok. But since it mentions specific information for flight instruction and that it has to be a required maneuver, I am leaning toward no. The spin example in the regs is telling as that is a required for the CFI which makes sense why they use it as an example.

Regarding flight test - Checkrides?

shdw

Update on Va, mind you I did not locate this, a friend did. Take special note of section B, however all of it is important.

From AC 23-19A Airframe Guide for Certification of Part 23 Airplanes:

48. What is the design maneuvering speed VA?


a. The design maneuvering speed is a value chosen by the applicant. It may not be less than Vs√ n and need not be greater than Vc, but it could be greater if the applicant chose the higher value. The loads resulting from full control surface deflections at VA are used to design the empennage and ailerons in part 23, §§ 23.423, 23.441, and 23.455.

b. VA should not be interpreted as a speed that would permit the pilot unrestricted flight-control movement without exceeding airplane structural limits, nor should it be interpreted as a gust penetration speed. Only if VA = Vs √n will the airplane stall in a nose-up pitching maneuver at, or near, limit load factor. For airplanes where VA>VS√n, the pilot would have to check the maneuver; otherwise the airplane would exceed the limit load factor.

c. Amendment 23-45 added the operating maneuvering speed, VO, in § 23.1507. VO is established not greater than VS√n, and it is a speed where the airplane will stall in a nose-up pitching maneuver before exceeding the airplane structural limits.

watchyouralt

Its unrealistic to say the turn would not have any acceleration. If you can do a perfectly level 60 degree turn that doesn't require you to pitch up and accelerate* to regain the 50 feet you just lost or whatever, then props. But if your goal is to remain completely level throughout the turn there will be slight accelerations at some time. And though G's pulled comes down to the acceleration of a mass starting at 1G in a steady un-accelerated state, speed does matter. If I accelerate the plane at 90KTS vs. 200 there will be a difference. Just look at a velocity-load factor diagram(VN) and notice how the positive G's increase with speed.

shdw

I would assume you are right here. What we have to do is find out how the FARs define "flight test," which I spent about 5 minutes on but don't have the time to continue right now. I will look into it more later and post what I find if nobody else does.

I am not saying I was not in the regulations or not. If I were to argue it though it would be along the lines the PTS requiring unusual attitude recovery. Since in the process of recovering from a UA you may experience a high g-load, it would beneficial to introduce a student to higher g flight to properly prepare them for an actual UA recovery. To do so without a g-meter isn't possible unless you use a constant bank turn, 60 degrees would only introduce 2gs. They could potentially pull, and even black out, from a 3g (up to 4.4 if in utility) recovery if not properly prepared. I review tightening core muscles and the breathing procedures to do so before this demonstration.

That would be my defense anyways, I guess I should write a letter to chief counsel and get their opinion on it. Will do that tomorrow and let you all know when I hear back.

ryan1234

I think your 'defense' would be a non-issue... something I've taken from my humble endeavor with law academia is that in the legal sense... you're not wrong unless someone can prove that you violated a regulation, and more specifically intentionally violated as it was not for any other exception noted (loss and recovery of aircraft control?), etc, etc. Proving the difference between a 80 degree and 60 degree bank without a flight data recorder by simple non-pilot bystander speculation is pretty much garbage.... so unless your actions resulted in some type of injury or damages you probably wouldn't need a defense anyways.

You may find this interesting:

Here is a case against a King Air diver driver:
http://www.ntsb.gov/alj/o_n_o/docs/AVIATION/4717.PDF

This case is thrown out even though a FAA inspector was the 'witness'...

although slightly not relative to our question at hand... it does put a new meaning to 'normal operations' that is crop-dusting and skydive operations will have normal operations some may consider aerobatic (could this include some aspects of flight training?). It also goes on to say that 'aerobatic' definitions vary and rely on previous adjudications.

plasticpi

You've misread that graph, it isn't saying that G's increase with airspeed, it says that with an increase in airspeed, you are capable of more G's than at a lower airspeed. In other words, the faster I go, the more Gs I can pull before an accelerated stall. When the accelerated stall happens at the max load factor limit, that's Va. Anything done above that speed must be done with care to keep the Gs below the limit. Below Va, you will stall before exceeding that limit.

Here is a good article on this subject: Aerospaceweb.org | Ask Us - Bank Angle and G's

Cubdriver

Shdw, I wish I had a friend like this one of yours who steps out of the shadows to supply aviation data whenever you happen to need it. A parent or uncle at an aviation school, he is? Maybe he or she could figure out how to nullify the useless Verizon contract I have while they are at it. Anyway, if you are implying that this AC says you do not get a stall before overstress, then this AC is not proof of the same.

1. By point (a) in this AC we know that Va is to serve as a benchmark for the subsequent design strength of the tail and other flight controls. The lower Va is the lighter such assemblies will need to be. So, it is rare for Va to be higher than the lower number, which is clearly defined as "not [to] be less than Vs√ n ." Perhaps it could be greater than this, according to this AC, but in most cases "Va" means you will get a stall before you get overstressing because it is a chosen value among two possibilities. If you want to argue otherwise (that it is higher), you need to show "the applicant chose the higher value." I certainly do not know of any cases where Va is defined to be higher than the usual, commonly known definition of Va we all know and love, but it's up to you to specify a Part 23 airplane that is. I doubt you'll find it, but you can ask your adviser if they know of one.

2. Sub-item (b) is, by obverse, a confirmation that the airplane will stall before being overstressed if Va is defined as "VA = Vs √n". I gave a reason why there is every reason to expect Va to be chosen as Va = Vs √n in point (1) above.

3. I am not familiar with Amendment 23-45 or the term "VO" mentioned in Sub-item (c), but it is beyond the scope of the present discussion since we are only talking about Va. If you want to make a relevant point here I think it should be that flying at or below Va does not assure a stall before an overstress condition in, and only in, negative-g maneuvers.

shdw

I sense some skepticism, so here: Certification standards and Va - Jetcareers

The poster, tgrayson, I consider a friend. Will read the rest of the post tomorrow, I am a little drunk right now so my reply would likely be useless, g'nite.

Fly Boy Knight

Freakin' awesome. Way to go NTSB. It is about time the FAA's "purposefully vague-ness" in their rules finally comes back to bite them and not the pilots!

shdw

Update: I have read about 70 percent of Part 23 and 20-30 percent of Part 25 in search of something more on Va certification. Tgray from the JC post I made 2 posts prior said, "There is no requirement that the aircraft stall before excessive load factors are applied to the aircraft." This is what I have been looking for in 23/25. He also brought up mention of, "dynamic stalls."

Maybe one of you other aerodynamics guys have more understanding of this, I only had a vague recollection of its existence, so I did some googling. Wiki defines it as, "a non-linear unsteady aerodynamic effect that occurs when aerofoils rapidly change the angle of attack." I also found some sources describing this as an effect that helicopter pilots can see. It causes a flutter in the rotor blades much like that of a bumblebee. Finally, another source said it may be the primary source of lift for small insect flight.

All that aside, the basis of my previous posts still remain true, though they are not directly used for testing Va. They are the only structural tests, related to Va, that I found, that must be achieved. Wind tunnel tests from the Cap 10B manual state this:



Snap maneuvers:

Recent wind tunnel tests showed that very rapid change of angle of attack could tremendously increase the maximum lift coefficient for that particular airfoil. This is due to the unstationary air flow. So, a quick and total deflection of the elevator at speeds equal to or even lower than maneuvering speed - Va = 127 kts (146 mph) -, combined with an aileron or rudder deflection could cause load factor limits to be exceed which could lead to structure damage. Therefore, the maximum authorized speeds for snap maneuvers are:

Positive flight: 95 kts (110 mph)
Negative flight: 105 kts (120 mph)




I am in the process of trying to get my hands on some other aerobatic aircraft POH's to see what their manuals state with regards to snap maneuvers.

You guys can do what you want, but I would suggest being careful if you are snapping those controls, especially if in any form of uncoordinated flight. Va is nothing more than a mathematical equation. We all know that they don't always account for all the dynamic effects involved in a flight situation.

Unless someone here can source a certification standard that requires full aircraft capabilities in snapping the controls, both in level and in turn, for an in and out of symmetry loading. In both cases, ensuring that a stall occurs without structural damage. Then I still have to stick with my original statement, "Va is not tested beyond progressive or symmetrical maneuvers." At least not in Part 23 or 25 certifications.


Cubdriver: Vo is in place since Va is not "required" to be = to sqrt(loadfactorlimit) * Vs, instead that is defined as the minimum for Va. So a manual could post Va as say 100 when sqrt(loadfactorlimit) * Vs = 80. Vo will have to be equal, or lower, then sqrt(loadfactorlimit) * Vs. Make sense?