Safety Concerns
Posted: Tue Jan 12, 2016 7:22 pm
by UtahClem
I have had a long hiatus (almost 4 years) since actively building a Sonex tail kit and am hoping to get back into it soon. I will try to be as sensitive to this topic as I can, since I know how tight knit the Sonex community is. However, my perception regarding overall safety of the Sonex line has changed somewhat since I first bought Sonex Plans #1398 and started building. What I once viewed as a sturdy little fun flyer with an impeccable safety record, now seems to have had a couple of rough years, safety wise. Obviously, some of that can be contributed to increased numbers of completed aircraft in the fleet, but I’m worried there is more to it. Comparing a search of the NTSB database for “Model: Sonex” vs say, “Model: RV-12”, the number is a little concerning. Now, let me be clear, I don’t want to build an RV-12. I have come to love the Sonex; it’s design philosophy, the way it flies (took a ride in Sonex #199 way back when), and the whole Sonex family, especially the Monnett’s. I respect the company and community they have built. The Sonex IS the plane I want to build. But, as a husband and father of 5, I owe it to my family to weigh the risks associated with everything I do. Obviously there is risk in our chosen hobby, but I want to make sure I have done my part to mitigate as much risk as possible.
What are others thoughts on Sonex safety? Has it just been a couple of bad luck years, or, is there something more at play? Is there a common thread running through any of the accidents (engine/carb, structure, etc.)? What can we learn to make each of us safer Sonex builders and pilots?
Re: Safety Concerns
Posted: Tue Jan 12, 2016 7:46 pm
by samiam
Josh,
This is certainly nothing that pilots and builders should be shy about talking about (IMO). You are correct in your observation of a bad run of accidents lately. There has certainly been some good discussion about it on this board. As a low time and young pilot, I shared many of your concerns as well.
Just some general thoughts:
-Look over the NTSB reports rather than just the number of accidents, and try to learn from them. It doesn’t help to look at the probable cause and say to yourself, “I would never do that”, but rather to look at it and say “How can I prevent myself from doing that.”
-Evaluate whether or not you feel there are any accidents inherent to the airframe design itself. Of course several of the accidents are still in preliminary, but on first brush it would not seem so.
A disproportionate number of fatal accidents have come from engine failures, either for unknown reasons or from the fuel system. I personally feel that this underlies how critical paying attention to safety in this area is. There is no substitute for sound judgement and using proven methods in aviation. (Anyone who is planning on using a Corvair engine can tell where I get this philosophy from!)
In the end, it is impossible to remove all risk from aviation. But I think that the mere act of posing the questions you are posing speaks to your commitment to development and safety in the field of homebuilding, in order to minimize the risk of human factors where at all possible.
Best,
Mike
Re: Safety Concerns
Posted: Tue Jan 12, 2016 8:34 pm
by fastj22
If you search the NTSB for RV, you will find a lot of accidents. Simply because there are a lot of RVs flying. Same search using Cessna and you will find a lot because there are a lot of Cessna flying. Sonex has few accidents because there aren’t many flying.
The airframe is as safe as any, tough as nails, no bad flight characteristics, will get you safely to the ground if you use your head. But the one thing the Sonex has that other kits don’t, is an amateur built engine in the Aerovee in many cases. RVs and Cessnas don’t, they use Lycomings. Sure, Jabiru accidents occur, and usually for similar causes, fuel exhaustion or non standard modifications or maintenance. And it certainly doesn’t help the situation that the CEO of Sonex was killed in an Aerovee powered Sonex.
I’ve had an engine out in my Jabiru caused by owner stupidity. I was able to dead stick it back to the runway. Would have happened no matter the power plant. I would fly behind a properly built and maintained Aerovee.
My point is the Sonex airframe is proven. Then engines are only as good as the folks who built them, installed them, modified them and maintain them. And keep enough fuel for them.
Re: Safety Concerns
Posted: Tue Jan 12, 2016 8:44 pm
by SonexN76ET
Josh,
I will second everything that Mike and John just posted. I would also like to add a couple of more thoughts on the subject.
First, there have been too many instances where the pilot attempted to return to the airport at low altitude after loosing engine power for whatever reason. They did not make it. On the other hand, a few Sonex pilots in recent accidents have maintained control and landed straight ahead and walked away with minor or no injuries, including a couple who landed in the tree tops.
A Sonex stalls at less than 40 MPH. If you loose an engine, that should be no worse than running your four wheeler off a trail at 40 mph, as long as you don’t stall and spin. So, do not attempt the impossible turn! I am thinking that because the aircraft is so manuverable, pilots think that they can cheat physics and make a low altitude turn to return to the runway. Train yourself not to give into this temptation!
The second point is there are very few, if any, instances of a catastrophic engine failure in the Sonex accidents. Some are due to maintenance errors, some to improperly repaired engines occurring after a propeller strike. Others are for indeterminate reasons. Whatever the reason, this means that you have to pay attention to detail when you install and maintain your engine. Make sure your engine is getting proper cooling air. Make sure your fuel lines are properly routed and secured. Make sure your engine controls are robust and properly secured, safety’d and routed. Make sure your induction system is properly set up and secure and safety’d. Make sure you fully understand all of the systems and how they work and how to inspect them.
There are no smoking guns in any of the accidents that I can find. Try to learn from the mistakes of others. Try to build in as much safety as you can into your aircraft (styrofoam under the seatpan, seat belts padded with racing should and waist pads, energy aborbing foam in your seat cushions, angle of attack indicator, etc.).
Practice ultra safe flight practices when you are in Phase One and after any modifications. These practices would include using an airport with long runways, flying high, remaining within gliding distance of a suitable landing area, never flying with less than an hour of fuel reserve, only flying in good weather in daylight, etc. Also, make sure you go to the Sonex transition flight training program and maintain your pilot education throughout your flying career.
I wish you the best of luck in your decision and your aircraft building!
Jake
Re: Safety Concerns
Posted: Tue Jan 12, 2016 8:54 pm
by kmacht
would like to clear up one misconception. An off field landing into the woods at 40 mph is not the same as running a car off a trail at 40 mph. Airplanes have virtually no crumple zones and very little i
in tge way of pilot protection should you hit something. This is true of not just sonex but rv, cessna, pipers, etc. Airplanes are built to be light not to withstand ant sort of impact.
As for the original question, go read the ntsb reports. After reading each one ask yourself if the same thing could have just as likely happened in another aircraft or was there something specific to the sonex. Raw numbers don’t mean much without the supporting data.
Keith
Re: Safety Concerns
Posted: Tue Jan 12, 2016 8:59 pm
by SonexN76ET
Just for the record, I said four wheeler (i.e. Polaris or Artic Cat, Yamaha, etc.) off the trail, not a car. One thing an aircraft has going for it is the wings will offer some protection as they hit trees, bushes, branches, etc and slow down the impact forces.
Jake
Re: Safety Concerns
Posted: Tue Jan 12, 2016 9:00 pm
by mike.smith
samiam wrote:Josh,
A disproportionate number of fatal accidents have come from engine failures, either for unknown reasons or from the fuel system.
Agreed. The Sonex airframe is a damn TANK! You’d have to work awfully hard to damage the airframe. Engines are almost entirely the source of accidents in the Sonex family. That has less to do with the Sonex itself, but rather the installation and maintenance of the power plant. And I believe the EAA statistics show that a disproportionate number of first-flight accidents are due to fuel system errors. That can happen with any engine.
I used to fly single pilot, single engine, IFR at night. But now I have a family and more commitments, so I don’t do that anymore. I’m not worried about the airframe; I’m worried about the engine. ANY engine.
As for handling, I find the Sonex a great handling aircraft, without quirks. I can stall straight ahead at 26kts indicated. I’m sure there is pitot error there from the high angle of attack, but the the point is I can go really slow and not have the airplane break to either side, simply by staying on the rudder pedals. I can slip with the flaps up or down, and it glides quite well. When I purposely spin the airplane I can stop the spin in little more than a half turn.
Re: Safety Concerns
Posted: Tue Jan 12, 2016 9:15 pm
by fastj22
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Re: Safety Concerns
Posted: Tue Jan 12, 2016 9:24 pm
by fastj22
I will second that the Sonex airframe is a tank. You can really abuse it and it will not show any sign of it.
If you are able to have controlled flight into terrain at 40 MPH, you should survive with only a bruise to your ego.
Re: Safety Concerns
Posted: Tue Jan 12, 2016 9:57 pm
by MichaelFarley56
If you have some time, go to www.sonexfoundation.com and look up some of the accident database research we’ve collected. We try to keep it up to date as best as possible.
After digging into the data, the overwhelming majority of all Sonex accidents, both non-fatal and fatal, can be broken down into two categories: Loss of engine power and loss of control.
Loss of engine power can either be fuel exhaustion (it’s happened more than once), poor maintenance on behalf of the owner (flying after a prop strike for example), or engine failure for undetermined reasons.
Historically, loss of control accidents occur to people unfamiliar to the Sonex. People who are just beginning test flying their recently-completed airplane, or people who just purchased an already flying airplane may run into this issue.
As others have already said, your best defense against these issues is preparation. Before you fly your airplane, make sure the engine is running properly and you have no mechanical issues. Also make sure you are ready to fly, hopefully by enrolling in the T Flight program or getting flight time in other Sonexes.
Welcome back to the community and I’m glad to hear you’re back to building!
Re: Safety Concerns
Posted: Wed Jan 13, 2016 3:53 am
by UtahClem
I appreciate everyones responses. I should have said, I myself don’t have any doubts about the toughness of the airframe, just didn’t want to rule that out if somebody else had a different perspective. In reading the NTSB reports I have come to the same conclusions as the rest of you…most accidents have been caused by fuel exhaustion, LOC, and unexplained engine failure. The first one I feel like I can mitigate by making sure to have a healthy reserve, etc. The second, like everyone has said, get as much transition training as possible. It’s the undetermined engine failures that bother me the most, especially since I’m pretty green when it comes to the firewall forward stuff. I have to admit, it has me wondering if the AeroVee/AeroInjector would really be the right engine choice for me. With a home airport at 4500’, I would love to use the AeroVee turbo; I’m just not sure I am comfortable with the safety record yet.
Again, I appreciate everyones input and for welcoming me back. I’ll continue to look through the older posts related to this subject so we don’t have to rehash stuff that has already been said multiple times.
Thanks.
Re: Safety Concerns
Posted: Wed Jan 13, 2016 9:32 am
by DCASonex
Also agree the Sonex is a tank, but I do see one area for significant crash survival improvement. I and I am sure others cannot reach the flap and brake handles with shoulder belts tight, and have seen to many photos of cashes that looked like pilot should have walked away from but did not. Strong fuselage is no help if one is tossed about in it, particularly if head can hit panel.
Now that hydraulic brakes are available from Sonex, no reason not to put control within reach. I made toe pedal brake operators, but have flow plane with brakes on control stick that also worked well.
For flaps I took the simple route and installed an electrical linear actuator Advantage is that control switch is right next to throttle so one hand stays on stick other on throttle; however, suspect it should not be that difficult to find a way to put direct mechanical operation within reach of all operators.
Another no-brainer addition is a panel mounted push pull cable to the fuel shutoff valve. This gives visual indication of the valve’s position, and allows quick shut off in event of emergency off field landing.
Taken together, belts can be tight from takeoff roll to full stop.
David A.
Re: Safety Concerns
Posted: Wed Jan 13, 2016 1:36 pm
by LarryEWaiex121
David,
You have made some very valid points when it comes to control layout.
No one can argue with the KISS principle that Sonex, the company has embraced since the very beginning. One can though, make some observations like you have in this instance that tells another story. A more complete story.
I’m a tall guy at 6’3". I fit amazingly well in my Waiex. I think after 4 yrs of flying accumulating 457hrs, I feel qualified to say there is room for improvement in the control matter.
I’m used to practicing emergency out situations. Having flown gliders for 10 yrs, every flight in an emergency. LOL Every flight your anticipating something going wrong and planning your escape. Every flight is dead stick, so, you get into the mindset of always looking. Where would I go?
For me one of my biggest concerns is this. I can not reach my fuel shutoff valve in the stock location without loosening my seatbelts. I can do both fairly quick, but? Its not the ideal layout in forcing one to do more procedures in a critical time.
I’m going to look at my arraignment and see if maybe I can improve on the situation and get to a panel mounted shut off. Whether cable operated, rod, whatever.
As for brakes, I’m in the process of installing the hydraulic brakes(been on shelf for two yrs) and plan the stock install. Clearly there are moments I wished I had differential braking in crosswinds. If a guy had differential brakes with the toes, one could land with small amounts of POWER that would improve the control effectiveness and increase crosswind control.
Twice in crosswinds of over 20kts I’ve had that lovely off runway excursion do to lack of available control resources. Its quite uncomfortable feeling an impending slow motion crash. Through skill and cunning (or luck) I worked out both situations with no battle scars on the plane or me. No bent parts or knocked over runway lights. Whew!
Both situations occurred far out of town and made me sweat not that actual event but the after fallout of maybe having dinged a prop or rolling a tire off the bead. Better planning could have averted both in all likelihood?
Having to remove your hand from the throttle to manipulate the brakes is less than ideal. Even a stick mounted brake makes more sense than the hand brake. At least for a conventional geared plane. The ability to use power and brakes together can make for a better day on a taildragger. I’m seriously going to look at the stick mounted option.
Unfortunately, most engine failures can be traced straight back to the fuel system install. That part just has to work. No if, ands or buts.
Larry
Waiex 121YX
Re: Safety Concerns
Posted: Wed Jan 13, 2016 8:13 pm
by mike.smith
LarryEWaiex121 wrote:David,
For me one of my biggest concerns is this. I can not reach my fuel shutoff valve in the stock location without loosening my seatbelts. I can do both fairly quick, but? Its not the ideal layout in forcing one to do more procedures in a critical time.
I’m going to look at my arraignment and see if maybe I can improve on the situation and get to a panel mounted shut off. Whether cable operated, rod, whatever.
I am also of the opinion that the stock shutoff is not the best condition, so I installed a pushrod. I made an offset on the ball valve and then put a rod-end bearing on the end of a hollow aluminum tube, with a handle at one end. When the rod is pulled all the way out, the fuel is off. A huge visual indicator when you are in or out of the plane. I adjusted the throw so that when the rod is all the way in, the valve is fully open (all the way in for “open” so it’s not in the way during flight). Because I threaded the end of the rod, I can do two things: 1) quickly remove the rod so I can remove the removable center section of my panel, and 2) adjust the throw on the rod to make sure the valve is fully open when the rod is all the way in. Here are some of my Kitlog pages:
http://www.mykitlog.com/users/display_l … 968&row=18
http://www.mykitlog.com/users/display_l … 979&row=13
http://www.mykitlog.com/users/display_l … 458&row=17
Removable center panel (held with 4 piano hinge sections):
http://www.mykitlog.com/users/display_l … 561&row=73
http://www.mykitlog.com/users/display_l … 244&row=60
http://www.mykitlog.com/users/display_l … 7932&row=1
Re: Safety Concerns
Posted: Wed Jan 13, 2016 9:46 pm
by fastj22
I agree that having all critical controls within reach while fully strapped in is best.
Over the 200+ hours I’ve put on my plane,
I installed electric flaps which are operated by a momentary switch on the panel. The stock flaps handle works fine, but it requires a significant pull and just didn’t seem natural.
Toe brakes. Can’t imagine landing with a hand brake. Its just natural to use your toes to brake.
A fuel cut off like Mike did. Originally had to loosen the shoulder straps to reach the valve. Like this much better.
Trim is electric and controlled on a high hat on the stick. Had the Dial A Trim and found it unnatural.
When I’m landing, my left hand is on the throttle, my toes ready to brake, my right hand on the stick with my thumb adjusting trim. I do have to release the throttle to flip the flaps switch.
Re: Safety Concerns
Posted: Wed Jan 13, 2016 10:14 pm
by rizzz
These are all modifications I will seriously consider once my phase 1 testing is over (10.5 hours to go as of this morning).
Starting with the toe brakes using John’s pedals (thanks again John :))
Safety Concerns
Posted: Wed Jan 13, 2016 11:01 pm
by Sonex1517
So many good points. Very little to add, but here I go.
When we started the Sonex Builders and Pilots a Foundation, we looked at all the accidents, and continue to do so. Michael Farley posted links to what we have, and ai do need to update it.
These conversations are important and need to continue.
One thing we have discussed a bit is something for us all to consider. Many of us learned to fly in certified aircraft, and many of those offer audible stall warnings. In addition to all these excellent safety enhancements, I would suggest that at a minimum adding a Lift Reserve Indicator or Angle of Attack indicator would be a good idea. Having an audible indication would also benefit safety.
I often wonder how many of these LOC accidents have their roots in sensory feedback.
My two cents - worth less than half that
Robbie Culver
Sonex 1517
Chicagoland
N1517S
Re: Safety Concerns
Posted: Thu Jan 14, 2016 4:50 am
by WaiexN143NM
Hi all and john,
What kind of electric motor( for the flaps) and actuator do u use on your waiex? Where is it mounted? Where did u get it?
Zenith aircraft uses electric motor drive for flaps. Maybe one of their units would work. This sounds like a good upgrade.
We installed a push/pull tube for the fuel, works good.
The DAR that inspected the plane had me sit in it all buckle up and work all controls.
WaiexN143NM
Michael Radtke
Re: Safety Concerns
Posted: Thu Jan 14, 2016 9:23 am
by DCASonex
Do not know what John used, but for my flap operator drive I used a model LACT6-12V-20 concentric linear actuator purchased from Pololu Corp in Las Vegas NV. These appear to be same as sometimes found at Surplus Center, about $100 either place. Drawing and photos of my installation are available.
David A. Sonex TD, CAE 3300.
Re: Safety Concerns
Posted: Thu Jan 14, 2016 10:12 am
by fastj22
I used one from Firgelli Automations.
https://www.firgelliauto.com/collections/rod-actuators
Chose the force and stroke.
I think I used a 150LBS 6 inch model.
Attached to the stock flap handle about mid point and to the bottom longeron against the side wall.
Removed the stock notched bracket and replaced it with a smooth one with stickers on it indicating the degrees of flaps.
It takes a bit of trial and error to get the proper throws for full flap extension and retraction.
Re: Safety Concerns
by vwglenn » Fri Jan 15, 2016 3:10 pm
My biggest safety concern is the powerplant(s). The reason for that concern is most of the accident investigations I’ve read don’t determine what caused it to stop, see no reason for the stoppage, or even which engine was installed for that matter. The variation of installations and equipment you can have under the cowl is just too great for the amount of effort (or lack there of) they put into these investigations. 90% of the time an NTSB agent never went to the crash site. They tend to only go to the high profile accidents. Our accidents are likely investigated by an FAA investigator who has a different end mission than the NTSB. For my own curiosity, I’d like to see an equipment list from the aircraft that crashed for no apparent reason. Mostly to determine if there are any common threads (Aerocarb, certain avionics, throttle quad, ignition system). An engine out I can handle. You’re chances of survival are high if you do the right thing. Be prepared!
Sonex has it where it counts in my opinion. The airframe is robust and the handling characteristics are fantastic. Everything I would want in a plane. My two biggest mechanical fears while flying are structural failure and fire. Both of which will kill you faster than anything. Neither are of much concern in the history of Sonex accidents I’ve read.
Most of the reports I’ve read can be written off as pilot error or some anomaly. The two accidents that haunt me are N732SX and N123SX. N732SX was simply an attempt at the impossible turn. What bothers me was the pilot was an ATP with tons of experience. He should have known better but he tried it anyway. It’s either an example of overconfidence or the overwhelming desire to get back to the runway. I tend to believe it’s the latter. The jury is out on N123SX and I don’t want to speculate. Based on the preliminary investigation, however, it looks like Jeremy was trying to get back to the airport as well.
So what do I take away from this?
1: The Sonex is a safe airframe.
2: Be ready for that engine out situation. Do your best to mitigate the dangers in case your engine quits.
3: You absolutely, positively, undoubtedly, MUST fight the urge that a runway is the only safe place to land.
Two personal experiences have made me think about #2 & #3 constantly.
The first was scud running over the GA/NC/TN mountains on my way home from OSH one year. I was with my friend in his Tampico and we were still legal VFR but just barely. I remember looking out the window at the ridges and rocky streams thinking “If we lose our engine here we’re dead.” We made it home without incident. Seven hours later that engine ate a valve (O-360) and my friend totaled the plane by landing in a small field. He was uninjured but he didn’t make the airport or even his first landing spot. He was on plan “C” when he landed. He had less than 150 hours as a Private Pilot at the time. If that valve had let go eight flight hours earlier, I doubt I’d be typing this right now.
Second was the on my last BFR in the 170. I had a simulated engine out. I picked a nice looking grassy field and pointed my plane at it. My instructor asked me why I wasn’t headed to the nearby airport which is what he wanted and expected. I told him I wasn’t SURE I could make it but I was positive I could put it down in the grassy field. We headed to the runway as a test of the glide capabilities of the old Cessna and we made the runway…barely. While I enjoyed testing the plane, I realize the actual experience may be detrimental to my thought process in an actual emergency. Ironically, testing the plane to it’s limits in the glide might encourage me to do so when I shouldn’t. Sometimes experience can be your enemy. I’ve seen real life examples of it many times at work.
As to flying a Sonex. I did my transition training with Joe. The only thing that was difficult to reach in the factory Waiex was the fuel valve. Joe had that problem licked. He simply would use his toe to turn it on and off. I imagine this would work for any average sized or smaller guy but the tall folks would have a problem because they probably don’t have enough room under the panel to move without bashing their knees. Neither the brakes nor the flap handle or any other controls were difficult to reach for me in the Waiex. I’m used to mechanical (man powered) flaps. It was what my 170 had. In a way they are much more effective. I can deploy them or retract them as slow or fast as my muscles will allow. My plane has a hydraulic brake on the stick. It does OK at stopping the plane but will barely hold it for the run-up. Reaching the fuel valve is a non-issue for me because the shoulder belts in #600 are tension reels. I simply lean slowly forward and I’m fine. What does concern me after reading this thread is the thought that a sudden stop could open the fuel valve. Since you pull it to the rear and at a right angle (parallel to the wing), it occurs to me it could get thrown forward and open up if the impact was strong enough. I will put some thought into that issue before my next annual and see if that’s something I want to fix.
My synopsis: The Sonex is safe. The only question mark may be the engine(s) but that is the same question mark for every single engine aircraft out there and why we train from day one for engine failures. In that respect, I don’t think my Sonex is any less safe than my 68 year old Cessna.
Glenn
Sonex #600
N889AP