Experimental Aircraft

donjohnston said:
Do you have a point other than overstating the obvious?

Or are you just shooting for 30,000 posts?
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Why does any of that matter to you
Do you feel you can dictate what others post here?

If my goal was 30k posts you'er helping
 
wanttaja said:
This is a rather hard analysis, as there's nothing in the FAA to indicate whether the plane is still flown by the original builder, and the NTSB doesn't always indicate whether the accident pilot is the original owner.

Still, I made a cut at the issue about seven years ago for a magazine article. Would flag an accident as being flown by a purchaser if 1) The NTSB report said so, or 2) The "manufacturer name" in the FAA registry was different from the current owner's name (manual process, mostly, to catch variations), or 3) The pilot had less time-in-type than the aircraft total time (with a ~2 hour buffer to account for ground test time).

Roughly half the accidents in my EAB database met these criteria. Accidents due to mechanical failures were down, relative to the builder-flown cases. This was expected, as many of the "teething problems" of new homebuilts are taken care of by the time the airplane is sold.

However, pilot error was, in fact, higher for the purchased airplanes...both the "Pilot Miscontrol" (stick-and-rudder errors) and "Pilot Judgement" (VFR into IFR, Fuel Exhaustion) categories.
purch1.jpg

What was even more interesting was the pilot's time in type at the time of the accident. Purchasers of homebuilts have a higher rate of accidents during the transition period.
purch2.jpg

The builders of homebuilt aircraft are apparently more dedicated to transition training than purchasers. Part of this higher rate is due to more Fuel Exhaustion and Maneuvering at Low Altitude accidents.

Ron Wanttaja
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Interesting stats. I wonder how kit builds compare to plans builds and scratch builds. That would be interesting to explore.
 
kmacht said:
Statistics are great to look at and analyze, until you become one...

For a long time the Sonex had a great safety record compared to the number of those built/flying. I decided to scratch build one in 2002, finishing it in 2012. Since finishing it there have been two factory aircraft (one with fatalities and one with very serious injuries) involved in accidents and I know of another builder who I kept in regular touch with by e-mail who died in his plane. In all three cases the NTSB determined the accidents were caused by a loss of power for unknown reasons. No matter how good you maintain your airplane or how sure you are that you built it right accidents like these are constantly in the back of your mind when flying. There is no way around it that flying a non mass produced airplane built by someone in their garage is always going to be statistically more risky. The design can be solid, the engine can be perfect, but one little mis-step in the build can cost you your life. Factory aircraft are built under controlled conditions with quality checks along the way. Experimental aircraft have none of that. They only require an inspection by a DAR at the end of the buid. The DAR is not going to check to make sure every bolt is tight, every wire is run correctly, all the rivets are set perfectly, etc.

Unfortunately I am starting to come to the realization that I may be ready to sell my plane. The risk/reward just isn't there for me aymore. Statistically I know that there is a better chance of getting in a car accident on the way to the airport, but that doesn't keep me from thinking about the above every time I fly greatly reducing the joy I once had for the hobby.

Keith
P.S. - Anyone want to buy a Sonex?
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First, on your Sonex, is it the airframe you are concerned with or just the engine? Is it a VW or a Jabiru? If it's the engine, would you consider changing it?

Second, on this comment:
Statistically I know that there is a better chance of getting in a car accident on the way to the airport.
I don't think that's true. For fatal accidents, I know it's not. Flying in a GA airplane is many times more dangerous than driving or riding in a car.


Tom-D said:
Hope you like double broken collar bones. but it's better than dead.
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I was involved in auto racing for 20 years. I saw lots of hard crashes, and was involved in a couple myself. I have never seen anyone break his collarbone. It just doesn't happen. The four and five point harnesses are excellent at restraining you provided they are installed correctly.
 
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26500 before he can do 4300...

That's only 6:1.

If I only had a book or some AoA indicators to sell I could pull it off.
 
FormerHangie said:
First, on your Sonex, is it the airframe you are concerned with or just the engine? Is it a VW or a Jabiru? If it's the engine, would you consider changing it
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The problem is that there is a large number of sonex accidents where the engine stops just after takeoff. Nobody has been able to pinpoint an exact cause. I'm not sure changing the engine out would make me feel any better about it. I have an aerovee and there aren't any other engines for the airframe that make sense. The jabiru and the aerovee are the only factory supported options. The jabiru has just as many issues as the aerovee. An o-200 is too heavy with the sonex 200lb firewall forward limit. A rotax costs 20k which just doesn't make sense when sonex are selling in the low 20k range.

It may be a perfectly safe airplane and engine and hasn' done anything to make me think otherwise. My confidence has just been shaken with the numbet and type of accidents where I don't know if it is worth the risk to me anymore.
Keith
 
Taking the train off the rails...

If you click it, you quite possibly may be offended.

 
donjohnston said:
Only pointing out that you post a lot without adding anything. Or are you trying to dictate what I can post?
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You are the one who seems upset over what I post..

I'll make ya a deal. I'll post what I like, you bit-ch about it.
 
Some thoughts on the homebuilts from a guy who moved from a Cherokee to an RV-9A seven years ago:
Insurance companies now often demand some kind of transition training. It would be interesting to see the accident data for Canada where liability insurance is mandatory.
My RV has the same engine and hourly fuel consumption as the Cherokee but am going about a mile a minute faster. Stall speed is about the same.
The RV is as easy to fly and land as the Cherokee.
The RV landing gear is not as robust as a trainer.
Parts are way cheaper including items that can enhance safety. A two axis autopilot (with a “180 degree” button to safely get you out of an inadvertent entry to IMC) was $1,500 for the RV. The same equipment for a Cherokee would cost more than the plane was worth.
 
wanttaja said:
The point is the relative sizes of the "roll cages," not how the aircraft met their demises. The J-3 is much slower, but more structure around the occupant's upper torso and head. Both increase survivability.
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I think what you said about the J-3 being slower has merit...less kinetic energy, more survivability. (What is it they say, that a Cub can fly just fast enough to kill you?). More structure can be a liability if the occupant isn't properly restrained as it's the secondary collision (the occupant against interior of airframe) that results in blunt force trauma, not the initial collision. Too rigid a cage and poorly restrained occupant can be more deadly than a properly restrained occupant in a structure that deforms somewhat to absorb some of the energy, like crush zones in cars.

That said, if I had to pick between my RV and a Cub in an engine-out forced landing...given that both had comparable 5-point harnesses...I'd pick the Cub, not because of its wing location but for its lower stall speed/lower kinetic energy. But I have to have something faster than a Cub! :)
 
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kmacht said:
The problem is that there is a large number of sonex accidents where the engine stops just after takeoff. Nobody has been able to pinpoint an exact cause. I'm not sure changing the engine out would make me feel any better about it. I have an aerovee and there aren't any other engines for the airframe that make sense. The jabiru and the aerovee are the only factory supported options. The jabiru has just as many issues as the aerovee. An o-200 is too heavy with the sonex 200lb firewall forward limit. A rotax costs 20k which just doesn't make sense when sonex are selling in the low 20k range.

It may be a perfectly safe airplane and engine and hasn' done anything to make me think otherwise. My confidence has just been shaken with the numbet and type of accidents where I don't know if it is worth the risk to me anymore.
Keith
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I can see where that would take all the enjoyment out of flying, and I'd get out of that airplane too. Losing an engine on takeoff is a pilot's worst nightmare.
 
FormerHangie said:
I can see where that would take all the enjoyment out of flying, and I'd get out of that airplane too. Losing an engine on takeoff is a pilot's worst nightmare.
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I would say worst nightmare inflight fire. Many years ago when I still smoked, was flying and my feet were slipping around on the floor. Looking down saw gas all over the floor and I was smoking at the time.
 
brien23 said:
I would say worst nightmare inflight fire. Many years ago when I still smoked, was flying and my feet were slipping around on the floor. Looking down saw gas all over the floor and I was smoking at the time.
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Yeah, that's a bad one too. I hope never to experience either.
 
kmacht said:
The problem is that there is a large number of sonex accidents where the engine stops just after takeoff. Nobody has been able to pinpoint an exact cause.
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That is interesting. Looking at my 1998-2015 homebuilt accident database, 56% of all Sonex accidents start with an engine failure, vs. 33% for homebuilts overall, and 14% for Cessna 172s. In addition, the NTSB was unable to identify the cause almost three times as often (27.8% of Sonex accidents are due to undermined engine vailure, vs. 9.6% for the overall homebuilt fleet.)

It's a small sample size (36 accidents in my database) but the overall engine failure percentage is high.

Ron Wanttaja
 
wanttaja said:
That is interesting. Looking at my 1998-2015 homebuilt accident database, 56% of all Sonex accidents start with an engine failure, vs. 33% for homebuilts overall, and 14% for Cessna 172s. In addition, the NTSB was unable to identify the cause almost three times as often (27.8% of Sonex accidents are due to undermined engine vailure, vs. 9.6% for the overall homebuilt fleet.)

It's a small sample size (36 accidents in my database) but the overall engine failure percentage is high.

Ron Wanttaja
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Single ignition system. as dependable as a mag is, How many builders will buy new?
 
wanttaja said:
It's a small sample size (36 accidents in my database) but the overall engine failure percentage is high.
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Tom-D said:
Single ignition system. as dependable as a mag is, How many builders will buy new?
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Only one of 20 loss of power scenarios specifically referenced the ignition system (ERA09CA162), and that was deemed improper installation of an automobile ignition control unit. Nothing was mentioned of the unit being anything other than new at the time of installation. It lasted 259 hours...wasn't an Aerovee engine, like most Sonexes.

Three of the 20 cases were pilot-induced, plus some carb issues and a prop-installation one. A couple of broken crankshafts.

The NTSB did not indicate the cause for half of the loss-of-power cases. The NTSB doesn't tend to allocate resources for homebuilt accident analyses, so the "Undetermined Loss of Power" result is more common than production airplanes.

The ten undetermined cases:

CHI08CA170: May have been fuel-contamination related, the plane's previous flight had used almost all the gas. However, no evidence of contamination during the exam.

WPR09CA152: First flight, loss of power. No cause found.

CEN09CA391: Stopped in cruise, no cause found. NTSB report refers to "The pilot attempted to restore power by adjusting the throttle, mixture, and magnetos," so the implication is that this was not a single-ignition airplane.

ERA11FA374: Post-crash fire precluded inspection. Jabiru engine.

ANC11LA060: External engine check found no anomalies, interior of engine was not examined.

ERA13LA024: Post-crash accident verified that spark was being delivered to the lower plugs, but couldn't test the top plugs. Pilot wasn't wearing his safety harness, so his collarbones were safe.

ERA13LA254: Engine lost oil pressure, no cause found.

ERA14LA018: Was able to start the engine after the accident.

ERA15FA003: No cause found due to damage. Engine had a history of fuel-system problems.

CEN15FA249: The Monnett case. No cause found.

Ron Wanttaja
 
wanttaja said:
Certainly. But the burned-out J-3 would still have a HECK of a lot more structure protecting the occupants. The point is the relative sizes of the "roll cages," not how the aircraft met their demises. The J-3 is much slower, but more structure around the occupant's upper torso and head. Both increase survivability.

Mind you, Mooneys will have some aluminum structure backing up what's visible above.

Ron Wanttaja
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I dunno, I’ve seen some seriously banged up Mooney’s where everyone walked away. The one that crashed into a house where everyone walked away was really impressive. Try doing that in a Cub.

Also, my sceptisim about your analysis had literally nothing to do with your methods. When numbers get close statistics is all you’ve got. I bet if you put error bars on that graph (yes, you do have error) I bet they’d overlap.
 
Ravioli said:
Easy there Francis... The A models of RV's are nose gear vs tail wheel. That can't possibly be what those old guys meant.
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no, it really applies to rv's... but i think you should never fly any number higher than 4........
 
FormerHangie said:
Second, on this comment:
Statistically I know that there is a better chance of getting in a car accident on the way to the airport.
I don't think that's true. For fatal accidents, I know it's not. Flying in a GA airplane is many times more dangerous than driving or riding in a car.
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I saw some rough statistical analysis a while ago which showed that safety in in light planes was about on par with motorcycles.

The stat which says flying is safer than driving to the airport was from the early 80s, and compared fatalities per miles traveled by airline to fatalities per miles traveled by car.
 
Eric Gleason said:
I saw some rough statistical analysis a while ago which showed that safety in in light planes was about on par with motorcycles.
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While true on the surface, if you took alcohol out of the mixture motorcycles would be far safer. The things that get motorcyclists are often abject stupidity. Yes, most motorcyclists are done in by cars and trucks. But most motorcycles have the speed and maneuverability to get out of the way. Of all the bikers I've known that crashed, most were doing something stupid when they did.

Aircraft crash due to more insidious things, like flying into increasingly bad weather. It can be a very difficult thing to know when to pull the plug and act before its too late. Flying an airplane also takes are more skill than riding an motorcycle, more things to go wrong.
 
steingar said:
While true on the surface, if you took alcohol out of the mixture motorcycles would be far safer. The things that get motorcyclists are often abject stupidity. Yes, most motorcyclists are done in by cars and trucks. But most motorcycles have the speed and maneuverability to get out of the way. Of all the bikers I've known that crashed, most were doing something stupid when they did.

Aircraft crash due to more insidious things, like flying into increasingly bad weather. It can be a very difficult thing to know when to pull the plug and act before its too late. Flying an airplane also takes are more skill than riding an motorcycle, more things to go wrong.
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From the statistics I've seen on motorcycle accidents, the most frequent accident is a single vehicle one, where the motorcyclist runs off the road in a turn. The authors also said that the second most common was a two vehicle accident where a car or truck turns in front of the motorcyclist, and that was slightly less common than the single vehicle one. Interestingly enough, by a slight majority, most fatal auto/truck accidents are also single vehicle.

Comparing a GA airplane to a motorcycle, IIRC they are similar in fatalities per occupant per hour, but since an airplane is faster, the per mile number is less. Since a lot of us who do either of those things aren't really going anywhere much of the time, I'm not sure the per mile stat means anything. And like @steingar said, if you ride cautiously and don't drink you can improve your chances of not getting hurt on a motorcycle by a good bit.

Comparing a GA airplane to automobile travel, they're not at all close, the car is safer by at least a factor of five. Don't drink and drive, and avoid driving the times and places that drunk drivers are most common, and the car is safer by an order of magnitude.
 
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