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Don Hall Accident Probable Cause

CFIT...

Jamie said:
I am dissatisfied with the report. I'm not saying that the final conclusion from the report was wrong, but that the information made available to the public was shallow and useless -- the entire point of these reports is to improve safety
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Jamie,
It's always tough reading reports after the fact, especially when it's a bro, it never gets any easier. Imagine burying 14 of your bros over a 25 year career, combat and training, many of them "CFIT inconclusive".In this case the report lends a classic "stall/spin" scenario or as they say, "controlled flight into terrain" CFIT.

Having spun numerous RV's and having spun several RV7's at various CG's, the spin entry and recovery is very straightforward even if inadvertently entered. Unusual attitude training and spin recovery is something everyone should practice or at least have demonstrated. Regardless of what they were doing or what happened, the end result was the same.

Lesson? Vigilance: Fly the @#$% Airplane, all the time...

V/R
Smokey
 
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Brantel said:
What would cause a pilot with this experience level in a RV end up in such a spin?
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There can be many reasons, including letting passengers fly. This is not intended as speculation on the accident pilot's experience, but ending up in a spin is not the biggest issue. Recovering from the spin is the biggest issue. Even experienced aerobatic pilots can occasionally depart controlled flight if trying something new. That alone is not a problem. Spin recovery experience is all that matters when one finds themselves in an accidental spin.

A pilot can have lots of experience flying, and even lots of experience doing aerobatics, but if they do not have significant experience (and currency) with emergency spin recovery in all spin modes, they can possibly become a statistic. Many experienced aerobatic pilots have died after failing to recover unusual spin modes. Most have been a result of confusion and improper inputs. If not experienced and current with emergency spin recovery from all spin modes, a lifetime of flying will do little to prepare a pilot for an encounter with an accidental and/or unusual spin mode.
 
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Called AFS...the slip value is acceleration-derived; the unit is G, not degrees.
 
cguarino said:
At -60 degrees pitch the aircraft is a .5g until you pull on the stick. Then the g load will increase as you pull the stick until an accelerated stall. What do you mean you can't pull 2.4gs at -60 degrees?
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Where does the data show .5G? It makes no sense to me that pitch would be going decreasing negative and still maintain +2.4G.
 
rocketbob said:
Where does the data show .5G? It makes no sense to me that pitch would be going decreasing negative and still maintain +2.4G.
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No, but maybe the plane could have started a dive *before* the data point was recorded, and been in the process of pulling out of a dive (nose 60 degrees below the horizon, upright) when the data point was logged?
 
@ Rocket Bob - pitch has no relevance as to the amount of g you can pull. Check the data again and you will notice that the aircraft was basically vertically banked in a nose down (-60degrees) attitude. All you have to do is haul the stick into your gut and - voila you will pull g. Try it in your borrowed 6. Consider the aircraft skidding and the airspeed increasing in this nose down knife-edged dive and the sustained g seems to support the accelerated deep stall theory. I would suggest you try this manoeuvre with plenty of altitude to spare! Possibly simply unloading the aircraft and taking the feet off the pedals may have had it flying again. It's just so easy to speculate from the comfort of an armchair.
 
Mounz said:
Possibly simply unloading the aircraft and taking the feet off the pedals may have had it flying again. It's just so easy to speculate from the comfort of an armchair.
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Looking at the data, I see the same scenario. A common, but very wrong, reaction to a spin is full up elevator because the airplane is descending, and rudder to fight the rotation. just releasing the back pressure can cure the problem, but without training it is counter intuitive to relax the back pressure, let alone push forward when the earth is rushing toward you. And yes, this opinion is coming from the comfort of a ground bound chair.

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
slip in 'g's

DanH said:
Called AFS...the slip value is acceleration-derived; the unit is G, not degrees.
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I was lying in bed thinking about it, and this is exactly what occurred to me. No beta-vane, they must be measuring slip as a lateral component of the gravity vector. Thanks Dan for confirming.

Two tenths of a g lateral acceleration......that's a spin.

The normal-acceleration varies between 1 g and 2.4 g's during the time there is so much lateral acceleration. This suggests a rather dynamic flight situation, such as the early stages of an evolving spin, where the spin axis is not vertical yet. The nose may be oscillating between -90 and -30 in pitch, with the sparse data sampling happening to catch a -60 on the way up (2.4 g) and then again on the way down (1 g). Admittedly, this last paragraph is speculative, but it does seem to reconcile with the available data.
 
I can't speak to the spin characteristics of an RV as I have never spun one, but the nose oscillating between vertical and maybe 30-40 degrees below the horizon is very typical of a spin in all other types of planes I have spun. At even points in the spin (1 turn, 2 turns, 3 turns, etc) your nose will be the high point, at the half points you will be closest to vertical. At the quarter turns you will appear to be yawed in reference to straight down, and the attitude halfway between vertical and the highest point. That is why competition pilots will prefer a 1&1/2 turn spin in a freestyle sequence, it allows the easiest transition to drawing a straight vertical line after the spin.

So if the characteristics of an RV are similar, I suspect a power on spin at low altitude is a good bet in this case.
 
rocketbob said:
Where does the data show .5G? It makes no sense to me that pitch would be going decreasing negative and still maintain +2.4G.
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Bob,

Here is some data from a test scenario that I flew last night for you to ponder:

testdata.jpg


Note the increasing negative (nose down) pitch while pulling over 3 g's...

Skylor
RV-8 N808SJ
 
Spin Data

Here is what spin data looks like from my airplane (no slip data recorded with my EFIS):

testdata1.jpg


Notice that I didn't exceed 1.31 g's until the recovery pullout.

Skylor
RV-8 N808SJ
 
Mounz said:
@ Rocket Bob - pitch has no relevance as to the amount of g you can pull.
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I get that. But if one is in a stalled condition 60 deg. pointed down, pitch is changing but G isn't I don't see how its physically possible to pull 2.4G.
 
skylor said:
Here is what spin data looks like from my airplane (no slip data recorded with my EFIS):


Notice that I didn't exceed 1.31 g's until the recovery pullout.

Skylor
RV-8 N808SJ
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Hi Skylor, that's very cool. Was your spin with power on or off? I don't know for certain, but it could affect the G forces recorded. As could the reactions of a pilot who is surprised by a spin, at low altitude, and sees the ground coming up rather quickly. With the power on, making recovery more difficult for an pilot without a lot of spin experience, I suspect it would be easier to pull some more G than normal, as in a spin done deliberately.
 
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N355DW said:
Hi Skylor, that's very cool. Was your spin with power on or off? I don't know for certain, but it could affect the G forces recorded. As could the reactions of a pilot who is surprised by a spin, at low altitude, and sees the ground coming up rather quickly. With the power on, making recovery more difficult for an pilot without a lot of spin experience, I suspect it would be easier to pull some more G than normal, as in a spin done deliberately.
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Yeah, idle only. I'm not all that wild about subjecting my engine to power on spins...

Skylor
 
Spin Research

In the 1970s and 80s NASA test pilots performed some 2500 spins involving some 8000 turns using general aviation type aircraft. The aircraft were fitted with spin chutes that, when an unrecoverable spin was encountered, would be deployed to stop the spinning, then be jettisoned to recover normal control of the aircraft.

In reading about some of this testing it was interesting to find that small changes could provide significantly differing results. For example, with a certain tail configuration in a Yankee, with neutral cg and symmetric mass distribution spin recoveries were normal, but with one wing 20 - 33 pounds heavier than the other spins toward the lighter wing were completely unrecoverable.

In another example of the NASA testing, the normally benign 172 would develop an unrecoverable spin at and beyond the aft cg.

Other examples include a test pilot testing a Mooney M20-B. The spin went flat and unrecoverable after 3 turns. The aircraft was loaded at maximum forward cg and maximum gross weight, normally a benign loading for spins. The spin chute had to be deployed in order to recover.

And in another example a test pilot was testing a new model of an existing low-wing design, loaded at aft cg. He entered the spin from a 60* 2g turn and the spin went unrecoverable during the first turn.

Researching the complete spin envelope of your experimental airplane should be done with the greatest amount of care. Wear a chute, practice your egress technique, always have a "bailout altitude", take a skydiving lesson, and do this research in an area that is devoid of people.

Oh, and you might want to have hull insurance on the airplane and insurance on your life.
 
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Mark is there a good reference book for sale that might be available showing the test results and general spin testing NASA did? I have seen some limited film of these spin tests in the past (very limited). I am very interested in this information from a flight safety and personal education point of view.

Cheers-
 
I just received this months EAA magazine. It has a recap of the RV6 that crashed near SLC. In reading that report I noted there are some possible connections to this accident. The main point I took away from both accidents is a AOA system with a audible alert might have prevented the accidents. I know this subject has been beat to death in the past on here with very differing opinions but I would not own a RV without a AOA system. If AOA did not prevent the initial stall it would certainly be helpful in secondary stall prevention.

George
 
Eddie P said:
Mark is there a good reference book for sale that might be available showing the test results and general spin testing NASA did?
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This book (the source of my info) has a chapter on these tests, and another chapter on one of the test pilots that was involved with these tests: http://www.amazon.com/Light-Airplan...8&qid=1370442279&sr=8-1&keywords=rich+stowell

In the bibliography a number of NASA documents are referenced, including one titled "Summary of Spin Technology as related to Light General Aviation Airplanes" by James S. Bowman, Jr. NASA TN D-6575, December 1971. This is available here: http://www.esdu.com/cgi-bin/ps.pl?sess=unlicensed_1130605143840grz&t=doc&p=nasa_tnd6575 I have not read this particular document.
 
Just an observation:

We're discouraged from speculating on accidents here, before the TSB/NTSB has a chance to review it and make determinations. And I do understand why that's the rule. But in this case, we've waited for the NTSB to make a report, and received something that was rather sparse... On its own it was not very useful with respect to the interests of increasing safety.

What has happened since is that readers here have dug deeper into the data, posting it here for us all to review and, yes, *speculate* on. This has happened in a well-mannered fashion, and I think some people may have learned something from it.

I'm not sure that this speculation couldn't proceed in a similar fashion *before* we have an NTSB report, provided the speculation is based on factual sources and not media hype. But that would be up to our fearless leader to allow... :)
 
Aerobatics

+1 on Mark's post. I only have 200 hours or so in competition acro but I never encountered an RV in a contest. In addition to egress practice, actual skydiving training (static line is best), I would add a spin endorsement before flying any acro in your RV. Spin training in a Pitts may be expensive but it may save your life.
 
Don

I was at Don's house about 2 weeks before the accident, he had just completed his new panel, and was getting ready to install it. Don lived about 4 miles from me and I was interested in going over to Stoney Point and seeing his aircraft but it never happened. This had to be the new panel installed New AFIS.

One thing that puzzles me if your familiar with the flight path, is that he was at such a slow airspeed over the lake (not even gliding speed for a 7)for a couple minutes prior to the crash. Pretty much his gliding path would tend to make you believe that he was possibly showing the passenger the gliding capability, he still had all engine readings so as not to indicate a failure

I'll throw this in just for thought.. Is it possible looking at the fuel flow that he had an interruption in fuel flow? All the engine data suggest a lack of power just 2 minutes prior to the accident resulting in such a slow airspeed over the lake and a pretty constant descend but the again it appears that he got it back.
A friend of mine an A&P was on his way home when the accident happened in front of him and he stated there was no fire and did not see any evidence of fuel leakage.
Prop damage was consistent with an engine not developing power.


Could have as suggested the passenger panicked, it has happened to me as an instructor twice in 3900 hours of instructing.
Like some accidents we may never know. But like most I too read these reports even after 15,000 hours of flying so that I can continue to Learn.

I thank all of you for bringing more information to light..
Smilin' Jack
 
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LettersFromFlyoverCountry said:
How do you find the backup data off the NTSB query page?
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As with many things, it's a little convoluted. You first go to the regular NTSB page and get the specific accident report, then copy the NTSB ID from it. Then you go to a different page here:

http://dms.ntsb.gov/pubdms/search/

Enter the correct information and you'll get a list of all the public data for the report. Sometimes you can get more, but it takes a bit of paperwork (like an FOIA, or being a "party" to the investigation).

Anyway, hope that helps. It's a little sad that I'm versed in this.....

Cheers,
Stein
 
Smilin' Jack said:
I was at Don's house about 2 weeks before the accident, he had just completed his new panel, and was getting ready to install it. Don lived about 4 miles from me and I was interested in going over to Stoney Point and seeing his aircraft but it never happened. This had to be the new panel installed New AFIS.

One thing that puzzles me if your familiar with the flight path, is that he was at such a slow airspeed over the lake (not even gliding speed for a 7)for a couple minutes prior to the crash. Pretty much his gliding path would tend to make you believe that he was possibly showing the passenger the gliding capability, he still had all engine readings so as not to indicate a failure

I'll throw this in just for thought.. Is it possible looking at the fuel flow that he had an interruption in fuel flow? All the engine data suggest a lack of power just 2 minutes prior to the accident resulting in such a slow airspeed over the lake and a pretty constant descend but the again it appears that he got it back.
A friend of mine an A&P was on his way home when the accident happened in front of him and he stated there was no fire and did not see any evidence of fuel leakage.
Prop damage was consistent with an engine not developing power.


Could have as suggested the passenger panicked, it has happened to me as an instructor twice in 3900 hours of instructing.
Like some accidents we may never know. But like most I too read these reports even after 15,000 hours of flying so that I can continue to Learn.

I thank all of you for bringing more information to light..
Smilin' Jack
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I see it has been brought up twice about the passenger panicking, does anyone know if the passenger was a pilot, a new person that had never flown etcetc... and here is something I haven't heard mentioned,, anyone thought of a possible medical emergency(heartattack) to the pilot, power could have been left set from pilots last movement, pilot went out, passenger panicking trying to wake up pilot(would explain long low power altitude drop) passenger trys to take control with no experience and stalls and no recovery,, I know its a forfetched thought, but it has happened several times over the years.
 
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I thought about the pilot incapacitation event myself... Usually in an exhaustive accident investigation there is a section dedicated to the aeromedical / flight physiology factors and autopsy information. Sometimes it is possible to know and other times it is not. In a non commercial investigation the exhaustive investigation and research work is just not done.
 
No one knows

Some accidents never have been resolved and there are many avenues of conjecture.

Methinks that this one falls in that category.

Best,
 
SteinAir said:
As with many things, it's a little convoluted. You first go to the regular NTSB page and get the specific accident report, then copy the NTSB ID from it. Then you go to a different page here:

http://dms.ntsb.gov/pubdms/search/

Enter the correct information and you'll get a list of all the public data for the report. Sometimes you can get more, but it takes a bit of paperwork (like an FOIA, or being a "party" to the investigation).

Anyway, hope that helps. It's a little sad that I'm versed in this.....

Cheers,
Stein
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Sorry to bring this back but the link is longer active. Anyone got a better one. There are some documents I'm looking for for the day job.
 
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