[apkp777]

There's been some discussion on another thread, that belongs in a new thread. I'll get this started.

It seems that it's possible that a VS and Rudder may have separated in flight from a unnamed RV-7.

One of the suggestions to the cause might have been improper over/under torquing of the attach bolts. In my career as an A&P for UAL I had the opportunity to hang many jet engines. On several occasions I would wake up in the night sweating and wondering "did I torque those bolts". Never a good question!

As a mechanic, the question "did I torque?" can only be answered by re-torquing. With only 3 or 4 nuts holding a large turbo fan engine on a wing strut, it's clearly an important question. Fortunately it's easily answered by checking the paperwork and the corresponding sign-offs. Still makes you nervous about the possibility of an oversight. I don't know how you use your builder's manual, but personally I initial every line when it's completed. I even initial the black spaces.

Our little RV's have the same all important fasteners. Torquing them is vital but easily screwed up. My first time torquing something important was on a Queen-Air during my powerplant practical exam. My buddy was holding the wrench but we were partners on the exam. We made the classic mistake of using FT/LBS instead of IN/LBS. Yikes, snap there went the stud for the 1 of 4 studs on the fuel pump (previously airworthy AC). Needless to say, lesson learned.

So yesterday I did a search for torque values for an AN 3 bolt with AN365 tension nut. The first hit came back with a PDF file from Matronics and lists the torque as 20-25 FT/lbs This is WRONG. There is no author of this document and not official in anyway. Still I am sure that individuals have used this "unofficial" document to torque their AN3's. To 12 times the correct torque value of 25 IN/lbs.

AC 43.13-1B should be on the bench of every builder and should be the sole reference document in lieu of manufacturer's specs. I really believe the builder of the aircraft in question did a fine job, and used correct techniques.

Personally, I think it's more likely that an over zealous "snap-roll" is more plausible. Remember the A300 that lost the tail because the pilots were over zealous controlling their engine failure?

 

[RV7Ron]

NAS bolts

AN3 bolts tend to be very fragile at the end of the thread. AN bolts are 125,000 psi rated strength. NAS bolts are 160,000 psi. NAS bolts are cheap insurance in critical areas.

I saw this posted on the other thread and liked the sound of it. From the guys with more experience than me, is there any flaw to doing this that I might be missing? I was taught that when making a repair in a skin (not quite the same, but similar concept) to not make the repaired area stronger than the original or you will introduce a stress concentration in that area. Does this logic hold with stronger bolts or would substituting NAS bolts be ok?

 

[Ron Lee]

Good question Ron. I am not a materials guy so this is merely my GUESS.

The bolts are in shear so increasing their shear properties is a possible positive in this application.

Just a guess folks. Don't act based upon this.

 

[apkp777]

The NAS bolts are more expensive and not really necessary in my opinion. 125,000 psi, is ridiculously strong. Especially when you consider that 6 of them (750,000 psi) are loaded in tension on the HS, 6 are loaded in shear. AN bolts are more than sufficient. After all they are common on all light and heavy aircraft. I am pretty sure that unless you damage them by over-torquing, there's no need to worry about them.

NAS bolts are more useful for installations where you can't use multiple fasteners and you need extreme strength of individual bolts. This is the case with engine bolts on large aircraft. Only 3 keep most engine on the airframe. If you remember way back, there was an American airlines DC-10 that crashed over Chicago, after one of those bolts was cracked because of the technique used to hang the engine. So even NAS bolts are not invincible. Still comes down to using proper torque and technique. Not to mention a quality, calibrated torque wrench.

I think when the cause of the RV7 crash is finally released we'll see that it had nothing to do with AN3 bolts.

 

[RV7Ron]

The NAS bolts are more expensive and not really necessary in my opinion. 125,000 psi, is ridiculously strong. Especially when you consider that 6 of them (750,000 psi) are loaded in tension on the HS, 6 are loaded in shear. AN bolts are more than sufficient. After all they are common on all light and heavy aircraft. I am pretty sure that unless you damage them by over-torquing, there's no need to worry about them.

NAS bolts are more useful for installations where you can't use multiple fasteners and you need extreme strength of individual bolts. This is the case with engine bolts on large aircraft. Only 3 keep most engine on the airframe. If you remember way back, there was an American airlines DC-10 that crashed over Chicago, after one of those bolts was cracked because of the technique used to hang the engine. So even NAS bolts are not invincible. Still comes down to using proper torque and technique. Not to mention a quality, calibrated torque wrench.

I think when the cause of the RV7 crash is finally released we'll see that it had nothing to do with AN3 bolts.

Thanks Tony, good explanation, I appreciate it. And although I have limited aircraft experience I am a Mechanical Engineer and I believe your argument is a good one. I just wanted to hear it from someone who knows about these things.

 

[apkp777]

Thanks Tony, good explanation, I appreciate it. And although I have limited aircraft experience I am a Mechanical Engineer and I believe your argument is a good one. I just wanted to hear it from someone who knows about these things.

I appreciate that. I am not an engineer, neither did I sleep at a Holdiay Inn last night, but did spend most of my life working on aircraft. Seen lot's of stuff that makes me wonder. Can honestly say I have never seen a failed AN3 bolt. For the record, most A&P's don't use torque wrenches on them 100% of the time. (wait while I duck to avoid all the bullets ).

 

[jrs14855]

bolts

I will rephrase what Tony posted to "I believe that many A&Ps do not use a torque wrench on AN3 bolts 100% of the time. In fact I have never seen anyone use a torque wrench on an AN3 bolt. This is exactly my reason for posting the NAS bolt information. I believe that the NAS bolts will stand up to considerably more overtorque than an AN. I also believe that at least SOME AN3 bolts have some manufacturing flaws. I am not suggesting that the much stronger NAS bolt is needed from a structural standpoint, just that the NAS will withstand a lot more "installation abuse".

 

[fl-mike]

I found a torque screwdriver to be much more useful for AN3 nuts. With a socket adapter it becomes a torque nutdriver.

 

[Ron Lee]

Where is the thread on this incident?

 

[apkp777]

JRS14855 - Yes, I wanted to be careful, truth is, I've never seen anyone use a torque wrench on them either.

A good 1/4" drive ratchet will give you a accurate and consistent torque. Seldom, if ever do I ever use 3/8 drive stuff. 1/2" drive should be banned from Aerospace.

Yes, the NAS would probably be a good alternative. I don't think everyone needs to go out and replace all their AN hardware though.

 

[DEWATSON]

Just for the heck of putting my two cents on the table, I always torque AN3 bolts to 25 lbs/inch. I've never felt like that was quite enough, but I've never had one fail either. Bolt stretch is figured into the equation when building performance engines in the automotive world and you can feel the point of "beginning stretch" when torquing engine bolts if you pull beyond the recommended torque. I've never felt this when torquing AN3 bolts with the small torque wrench, but I've never pulled beyond the recommended torque either.

Honestly, for the VS to come off of an airplane, either the front or rear attachments would have to come completely lose at which time the resulting flutter would tear the other end off. I have no idea what may have happened to the airplane in question, but for at least four AN3 bolts to break at once because they may have been overtorqued doesn't seem likely unless there was some significant load induced rather suddenly. I'll have to agree with the snap roll theory or the impact of a big bird on the leading edge of the VS.

If the proper lock nuts were put on the bolts and run up to eliminate all of the play, but not torqued, eventually the pilot would feel something strange in the airframe as they loosened from wearing out the holes through the attach points. I ALWAYS put torque seal marker on the bolt/nut AFTER I torque the bolt. If there is no torque seal marker on the nut and exposed thread, that bolt is revisited.

And please.....I am not pointing fingers at anyone with this post......I just want to discuss the possibilties and try to learn from this very unfortunate accident.

 

[RV7Ron]

or the impact of a big bird on the leading edge of the VS

This was also my thought...but gosh, how much of a one in a million chance would it be for a bird strike to miss the prop and canopy (an assumption) and take out your VS??

 

[apkp777]

And please.....I am not pointing fingers at anyone with this post......I just want to discuss the possibilities and try to learn from this very unfortunate accident.

Hey nothing wrong with finger point on this thread. Just not the original one.

I am just finding it difficult to even imagine what could take the tail off the RV. Seems unlikely bolt failure.

We all saw the photos of the RV with the tail sliced off in a "fly by wire" trick. Must be pretty strong to withstand that. It would have had to have been a side load to get the thing to fail.

 

[Ted RV8]

Keep In Mind

Originally Posted by apkp777
The NAS bolts are more expensive and not really necessary in my opinion. 125,000 psi, is ridiculously strong. Especially when you consider that 6 of them (750,000 psi) are loaded in tension on the HS, 6 are loaded in shear. AN bolts are more than sufficient. After all they are common on all light and heavy aircraft. I am pretty sure that unless you damage them by over-torquing, there's no need to worry about them.

125,000 PSI - The PSI is pounds per squre inch. This is relating to the area of the material. An AN3 is .190 diameter. Apply the formula "Pi R sqaured" to get the area equates to: .095 X .095 X 3.142 = .028 square inches. This number times the 125,000 gives you the strength of the bolt:
125,000 X .028 =3,500 lbs strength per bolt. This is also the ultimate strength. Still a lot of strength for such a small bolt. The amount of force that is exerted on the bolt by the force imposed by the threads when tightening a nut can easily over load the bolt.

The only reason I'm saying this is this could be part of the reason people over torque small bolts. Thiking 125,00 PSI is so strong.

As far as switching to the higher strength NAS bolts. As you increase the strength of steels you typically also decrease the ductility of the steel and they can break easier under certain conditions. Every bolt has it's proper place. I tend to stick with what the engineers calculated for stress and loads and go with that. If you are going to second guess the engineer at least be qualified to make educated calculations to qualify why.

 

[avangel]

I am just finding it difficult to even imagine what could take the tail off the RV. Seems unlikely bolt failure.

We all saw the photos of the RV with the tail sliced off in a "fly by wire" trick. Must be pretty strong to withstand that. It would have had to have been a side load to get the thing to fail.[/QUOTE]

I too am concerned with this.(tail coming off an rv series aircraft) as obviously I'm sure we all are.

I find the over torquing of these bolts interesting.

I'm curious as to where the rudder counter weight is located on an 8. How secure are these attached? I apologise for the foolishness of this question but I'm not a builder so please bare with me.
Is the tail the first component built when these kits are started?

Hitting a large bird certainly concerns me, especially at speed.

I'm not familiar with fly by wire trick.

 

[apkp777]

Originally Posted by apkp777
The NAS bolts are more expensive and not really necessary in my opinion. 125,000 psi, is ridiculously strong. Especially when you consider that 6 of them (750,000 psi) are loaded in tension on the HS, 6 are loaded in shear. AN bolts are more than sufficient. After all they are common on all light and heavy aircraft. I am pretty sure that unless you damage them by over-torquing, there's no need to worry about them.

125,000 PSI - The PSI is pounds per squre inch. This is relating to the area of the material. An AN3 is .190 diameter. Apply the formula "Pi R sqaured" to get the area equates to: .095 X .095 X 3.142 = .028 square inches. This number times the 125,000 gives you the strength of the bolt:
125,000 X .028 =3,500 lbs strength per bolt. This is also the ultimate strength. Still a lot of strength for such a small bolt. The amount of force that is exerted on the bolt by the force imposed by the threads when tightening a nut can easily over load the bolt.

Yes, my math (750,000) was flawed. Still its 4-6 bolts at 3,500. I am sure that's well within a margin of safety. I'd be curious to know what the flight loads are on the tail section.

 

[apkp777]

yikes, are 1/2" drive ratches known to be inaccurate? I recently bought a big torque wrench to do my prop bolts, and it has a 1/2" drive. THOSE bolts (and the ones for the prop extension) scare the heck out of me - they must be under so much strain spinning that prop around to pull the whole airplane through the sky.

Not the torque wrench, just 1/2" drive ratchets are usually way to heavy duty for aircraft stuff. You would have a hard time over-torquing a bolt if you use a small ratchet. Prop bolts probably might be an exception for the need for a larger ratchet/torque wrench.

 

[prkaye]

but how high do big birds cruise? I believe the RV-7A in question was cruising at 2 or 3 thousand feet... do big birds go this high?

 

[Garage Guy]

http://www.fws.gov/blackwater/canadageese.html:

"Geese have been observed at altitudes of 29,000 feet, although the normal migration altitude is only 3,000 feet."

--Paul

 

[prkaye]

wow, i had no idea. Ok, so that is definately a possibility then.

 

[boom3]

This is in the new EAA Sport Aviation magazine.

 

[pierre smith]

Yes...

........ Are there maneuvres that could specifically put high side-loading on the tail and leave the wings undamaged?

........an un-named acquaintance of mine laid the VS over on Globe Swift after a botched snap roll at too high a speed. Fortunately, he managed to land the airplane.

If you stomp a rudder, it puts an incredible side load on the VS and its attach points and little or none on the wing spar, especially above VA (max maneuvering speed).

However, a snap roll takes generally, full elevator and full rudder, in the direction you want the snap. This does put an immediate load on the wing spar and the stabilizer spar, bending the stab downward with full up elevator.

Best,

 

[avengingangel]

This is in the new EAA Sport Aviation magazine.

this is very real. Soon the geese will be on their way through north. At my airport we have a body of water very close by and geese are a problem.

scary stuff.

 

[RV7Ron]

This discussion has brought two questions to mind for me.

1. Let me preface this by saying I have no acro training yet but I read plenty. How many guys regularly perform snap rolls in their RV's? From what I've read, an RV airframe can handle a properly executed one. But done improperly, it can put some extreme stresses on the tail as Pierre mentioned. I always had figured for me personally that a snap roll would be better suited for a stronger airframe if I had that itch. Just wondering what the experienced guys say?

2. If you lost your VS and rudder and the HS remained intact, could you control the plane enough to attempt a landing? Intuitively I would say yes (lots of pilots fly without rudders in perfectly good planes ). Planes has stayed airborne without rudders and at least with partially removed VS...but what about both?

 

[apkp777]

Back in A&P school they showed us all the military B&W footage of aircraft that were ripped to shreds by geese. Thus the advent of the now famous "Chicken Gun" movie. Where they shoot a 5 lb frozen chicken at the windshields aircraft to test their strength. There's no doubt that a goose could have easily taken out the tail.

A few years back a Delta 767 took a goose through the radome, through the fwd pressure bulkhead and through the instrument panel, dislodging the captains EFIS display with goose guts all over everywhere.

 

[billgill]

Earlier wire strike report

This is in regards to the wire strike thread mentioned earlier. This was posted on VAF last SEP or OCT...wasn't able to find the thread (copied and pasted from a google link). Here, most of the VS is gone and the entire rudder is missing. I don't understand why one would not be able to control an aircraft without the VS unless its in-flight departure caused damage to the HS and/or elevators.

Update on Tail-sliced RV-9A ...fwd'd to me, "More info...RV-9A wire strike/vertical stab-rudder amputation. Interesting!"
- Airspeed when it occurred? ? 137 mph
- How did the aircraft handle with the damage? ? the plane maintaining its stability. It could only notice that the rudder was not there because the pedals went down. The behavior was just normal.
- Yaw? - no yaw
- Roll input? ? perfect
- Power changes? ? none
- Landing characteristics? ? it kept the same characteristics and the only problem was no rudder.
- Did the rudder pedal assembly sustain damage in the forward cockpit? ? he will check if pedals are ok.
- Any damage to bulkheads along rudder cable routing? ? he will check that too and will advice.
- He flew for 15 minutes with no problem (to get to the airport).

 

[DEWATSON]

I wonder if the VS was deformed on the upper portion indicating impact from something hitting it while in flight. According to the information provided above and looking at the profile of the airplane, a big bird could pass over the propeller and canopy and hit the upper portion of the VS.

This post has created a lot of pretty good thinking. There are a lot of things we don't know without seeing the VS, but it seems that we all agree on several possibilties. I guarantee I'll be looking for the big birds a lot closer than I have in the past whether one had anything to do with the accident or not!!!!!

 

[RV7Ron]

wow - that is a real testiment to the RV design, that he was able to control the airplane down to landing with almost no VS and no rudder! Reminds me of the F-15 that was landed with one wing missing.



Which is exactly why people shouldn't discourage speculation... it is how we toss ideas back and forth to share ideas and knowledge in the search for an answer to an unknown problem. I wasn't aware that the other thread was supposed to serve as a memorial - there was no indication of that on the thread or in the forum rules - but it does indeed make sense to separate the discussion from the expression of sympathies.

This was shown in the RVator also, a bigger picture.

http://www.vansaircraft.com/RVator/2009/5-2009-RVator.pdf

 

[avengingangel]

ya, that is something. Military quality in those RVs.

 

[Garage Guy]

How many guys regularly perform snap rolls in their RV's?

I don't think many do. Even if, like me, they like doing snap rolls in other planes. I haven't snapped my RV-6 and I don't plan to. Van advises against it http://www.vansairforce.net/safety/AnAerobaticEpistle.pdf:

One maneuver conspicuously absent from the above list is the snap roll. This is a maneuver I feel the RVs are not well suited for because high G forces are needed to produce a brisk snap roll. The low stall speed, and thus the low maneuvering speed, of the RVs limit the speed range in which snap rolls can be performed... A careless approach to snap rolls can overstress the airframe and cause structural failure.​

At very slow entry speeds it shouldn't be a problem, but then you'll be doing more of a one-turn spin than a snap roll. Faster, you'd get a better horizontal line, but how fast is too fast? Just not worth it IMHO.

--Paul

 

[lostpilot28]

This discussion has brought two questions to mind for me.

1. Let me preface this by saying I have no acro training yet but I read plenty. How many guys regularly perform snap rolls in their RV's? From what I've read, an RV airframe can handle a properly executed one. But done improperly, it can put some extreme stresses on the tail as Pierre mentioned. I always had figured for me personally that a snap roll would be better suited for a stronger airframe if I had that itch. Just wondering what the experienced guys say?

2. If you lost your VS and rudder and the HS remained intact, could you control the plane enough to attempt a landing? Intuitively I would say yes (lots of pilots fly without rudders in perfectly good planes ). Planes has stayed airborne without rudders and at least with partially removed VS...but what about both?

I think it would be a real stretch to control an airplane without having some yaw stability. The only reason (I believe) that the RV in the picture with about 1/3 of it's VS remaining was flyable was because it had SOME yaw stability. Without having any VS at all, overcoming the adverse yaw when banking would make an airplane very hard to control.

 

[lostpilot28]

Strange...

I just noticed that my previous post in this thread is missing. I asked if someone could do the math on how large a bird would have to be to completely remove the VS on an RV. Basically an inquiry to the strength of the VS mount & structure. Was that offensive to someone?

 

[DeltaRomeo]

I just noticed that my previous post in this thread is missing. I asked if someone could do the math on how large a bird would have to be to completely remove the VS on an RV. Basically an inquiry to the strength of the VS mount & structure. Was that offensive to someone?

I deleted some of the posts in this thread that I interpreted as being speculative. I'd prefer people wait until the final report comes out. Having been on the recieving end of some emails from family members involved in crashes in the past, I'm sensitive to this sort of stuff. Please refrain from speculating on crashes until a final report has been published.

Kindest,

Doug
(owner)

 

[Ted RV8]

Good Call

Good call by Sam Buchanan and Paul Dye on the other thread. Excellent moderating

 

[apkp777]

I think what makes this subject so interesting is deep down, some of us feel like "I really don't know what the heck I am doing!" The spirit of aviation lies deep in the soul and not always in the skills of the fingertips. When something tragic happens, it is natural to ask why and to think "yep, I could have done that". We all want answers, even when made clear, there will always be a shadow of grey. I have read Bernouli's principle a dozen times, taught it to hundreds. Still when a 800,000 lb 747 taxis into position I think "there's no freakin way that this is getting airborne." But that's why we fly. If you get all the answers, then it would become dull. Mystery is part of the thrill.

In the end we may never know all the causes or contributing factors in a particular crash. Murphy is out to get us all. If anything we just need to take a step back and rethink our own approach to life and hobby.

 

[prkaye]

deep down, some of us feel like "I really don't know what the heck I am doing!"

I absolutely feel like that, most of the time! I'm basically finished my build and I still feel like that. The other day I was trying to put together a document for my maintenance plan, and was reading through a couple of condition inspection checklists written by other RV builders. I realized I don't have any idea how to do many of the engine-related tasks mentioned on these checklists. So I ordered-up a copy of the Sky Ranch Engineering Manual and have vowed to read it cover-to cover this spring.

I recently went up for a pretty thorough flight-review as part of a recurrency check on the Grob 115C. After realising how rusty I was on several of the flight exercises, I said to the instructor with a deep sigh "I feel like a student pilot again!". As I get older I get less and less confident, in just about everything. Hopefully this keeps me alive.

 

[apkp777]

As I get older I get less and less confident, in just about everything. Hopefully this keeps me alive.

I agree. I take nothing for granted. It's what makes this forum so important. Where else can you sample the thoughts of hundreds on any given subject. Makes things a whole lot easier.

 

[avengingangel]

for sure. That's why this forum is here. I appreciate the help I've received over time from the builders out there.

Phil, you should be after your neighbor for a ride in one of those jets. That would get you current in no time, That would be quite a ride wouldn't it?

 

[DeltaRomeo]

snip....As I get older I get less and less confident, in just about everything....snip

I feel exactly the same way, Phil. My flying gets more and more conservative, and the folks around my airport that are older than me are even more conservation (trend continues). I think it makes me safer, also.

 

[jrs14855]

snap rolls

A snap roll is simply a forced autoratation on any axis. The entry ABSOLUTELY DOES NOT require full elevator. The optimum snap roll occurs when just enough elevator is applied to exceed the critical angle of attack on at least one wing, or in the case of a biplane, at least the wings on one side. In the case of an inside snap, the fastest autorotation occurs if the elevator is placed to a neutral or slightly down position as soon as possible after the start of autorotation. Most pilots new to snap rolls use way too much elevator.
Snap rolls put incredible loads on an airplane when performed at too high a speed. The reading on the G meter only presents the load incurred by the entry. The G meter does not show the twisting loads placed on the iarcraft, especially the loads on the tail cone and empennage.
I believe there is at least one RV8 that has been flown in Intermediate level competetion. Intermediate requires snap rolls. Doing safe snap rolls is all about absolute speed control.

 

[GLPalinkas]

I feel exactly the same way, Phil. My flying gets more and more conservative, and the folks around my airport that are older than me are even more conservation (trend continues). I think it makes me safer, also.

Doug, Thus the very old adage:

"I've seen many bold pilots and many old pilots. I haven't seen many old, bold pilots".

I too, have scaled way back in what I am willing to "try" in favor of "experience". Not that I want to lay in bed and hope the ceiling doesn't fall in. I'm just not bungee jumping or jumping out of perfectly good airplanes anymore.

Tailwinds,

 

[IowaRV9Dreamer]

yes, big birds fly high

but how high do big birds cruise? I believe the RV-7A in question was cruising at 2 or 3 thousand feet... do big birds go this high?

I almost hit a bald eagle at 3500 this fall. He was a few feet above on the pilot side - I pulled hard up and right. I saw his claws as he went by my window and under my left wing.

When I recovered I wondered if it was a federal crime to kill a bald eagle with a Beechcraft.

 

[prkaye]

Phil, you should be after your neighbor for a ride in one of those jets.

One of my dreams has always been to ride in a jet fighter (when I was a kid my life dream was to be a CF-18 pilot, but a serious head injury in a car accident when I was 17 put the kibosh on that dream). However, flying with my hangar neighbour in one of those old machines is not on my to-do list (I won't get into the reasons why - except that one of the reasons is that I couldn't even afford the fuel bill for a circuit in one of those jets!). They sure are nice to look at, and fun to watch flying around Smiths Falls anyway. Bobby's collection, and our gorgeous new clubhouse, make our airport a really interesting and great place to be. There are a lot of super folks in the flying club too.

 

[avengingangel]

ya, I was in there on Wednesday. you guys have certainly done a beautiful job on your new club house. Awesome. I hope you'll have a small restaurant this time as well.

 

[prkaye]

>> you guys have certainly done a beautiful job on your new club house

Steve Busy (an RV-builder and forum contributer here) was the man in charge of that project - we had lots of volunteer work and donations, but Steve really put the whole thing together.

 

[Christopher Murphy]

Snap rolls

A snap roll is simply a forced autoratation on any axis. The entry ABSOLUTELY DOES NOT require full elevator. The optimum snap roll occurs when just enough elevator is applied to exceed the critical angle of attack on at least one wing, or in the case of a biplane, at least the wings on one side. In the case of an inside snap, the fastest autorotation occurs if the elevator is placed to a neutral or slightly down position as soon as possible after the start of autorotation. Most pilots new to snap rolls use way too much elevator.
Snap rolls put incredible loads on an airplane when performed at too high a speed. The reading on the G meter only presents the load incurred by the entry. The G meter does not show the twisting loads placed on the iarcraft, especially the loads on the tail cone and empennage.
I believe there is at least one RV8 that has been flown in Intermediate level competetion. Intermediate requires snap rolls. Doing safe snap rolls is all about absolute speed control.

If the designer of the aircraft recommends that snap rolls not be performed in a specific design it would be foolish to do them. Just because the aircraft can do a certain manuever doesn't mean they should be done. ie. The Globe Swift can spin but the flight manual prohibits spins. You might do 100 snap rolls without a problem but the repeated stresses might cause a problem on number 101.

In one post it was mentioned that the pilots of an AA A-300 ripped off the Verticle Stab by responding to an engine failure. They were actually responding to a wake encounter. Air carrier pilots were being trained to respond to upsets with rudder input.

Chris M

 

[pvalovich]

Condition Inspection Concerns

What is a Sky Ranch Engineering Manual?

 

[az_gila]

Link here...

What is a Sky Ranch Engineering Manual?

http://www.sacskyranch.com/pubsem.htm

It's worth the $$$$