Oscar Posted February 24, 2014 Share Posted February 24, 2014 Oscar I will see if I can dig the pics up from the original accident. Not that much can be seen, but i cant recall if the rear spar connection failed or not. I dont think it did. Merv, from the description, I doubt it did; to tear along the spar you'd have to have a major shear load in the wing skin as you said, so if the rear attachment had failed then that would release the shear load. Once the shear strength has gone, then the load on the rear attachment reduces dramatically, so it's one or the other goes first... Your surmise that the tear started from a high stress point introduced by an interruption to the skin sounds entirely likely, though obviously the skin/mainspar attachment produces a line of high stress that could act a bit like the fold in an envelope.. The solid wings are as tough as hell, basically; they'll withstand a crash that cuts them open from the l/e back to the spar ( e.g. hitting a fence post or the like) and be entirely repairable. They're only a write-off if the spar is damaged. I don't know much at all about the later wings so can't comment, but I guess it's the old story: more technology, less forgiveness. There just is no free lunch; the reason a J120 can be put out Jab's door for such a low cost for what you get is a factor of the cost of production: those solid wings are cheap to make (and repair) but you trade that off for losing the room behind the seats to a fuel tank and a lower useful load. It all comes back to the rather complicated equation of 'what do you want from your aircraft'? If I were flying mostly one-up and wanted a minimum-maintenance, reasonably-performing, safe if it all goes pear-shaped device (which I do!) that I can head out to most anywhere in this country, a J120 with a full CAMit-modified engine would be damn hard to beat for the money - possibly impossible to beat. Pack 200 mls of LC3600 and a sandwich-bag full of appropriate 'glass and you can repair it pretty much anywhere en-route that you have a mid-level oopsy, if you have the basic knowledge of 'glass repair techniques... and your chances of being in a physical condition to DO a repair is pretty damn good. 1 Link to comment Share on other sites More sharing options...
Oscar Posted February 24, 2014 Share Posted February 24, 2014 That reads somewhat scary. The RV story .Steer with rudder?? Sounds like it flys like a brick, with the engine silent . Nev Just think about that report: the author is saying that if you are lower than 3,000 AGL, your landing options are bugger-all, or in RAA terms, about what you should adopt as a strategy from 1,000 AGL or less. Pick the softest spot... In gliders, it used to be the 'rule' that you committed to landing if in no lift at 1,000 AGL . I have done climb-outs on weak thermals from less than that, but I could see the damn lift from the dust etc. Ingo Renner used to consider 300 AGL to be a decision point - and I don't believe he ever bent an aircraft. But Ingo was a god, a thermal-whisperer. The rest of us aren't. Things like the RV6, or (and I think possibly the most dangerous aircraft ever foisted on the market) the Lancair 3x series, get across the countryside in a splendid fashion until the noise goes out. The Mitsubishi MU-2 is another. These are aircraft that basically if the prop(s) stop turning, you are praying..sometimes the gods wink in your favour; often they don't. Link to comment Share on other sites More sharing options...
Guest Nobody Posted February 24, 2014 Share Posted February 24, 2014 Just think about that report: the author is saying that if you are lower than 3,000 AGL, your landing options are bugger-all, or in RAA terms, about what you should adopt as a strategy from 1,000 AGL or less. Pick the softest spot... In gliders, it used to be the 'rule' that you committed to landing if in no lift at 1,000 AGL . I have done climb-outs on weak thermals from less than that, but I could see the damn lift from the dust etc. Ingo Renner used to consider 300 AGL to be a decision point - and I don't believe he ever bent an aircraft. But Ingo was a god, a thermal-whisperer. The rest of us aren't.Things like the RV6, or (and I think possibly the most dangerous aircraft ever foisted on the market) the Lancair 3x series, get across the countryside in a splendid fashion until the noise goes out. The Mitsubishi MU-2 is another. These are aircraft that basically if the prop(s) stop turning, you are praying..sometimes the gods wink in your favour; often they don't. You are probably better off thinking of the time to get to the ground rather than the height as a decision point. In a glider at 1000ft agl you proabaly have the best part of 5 minutes until you are on final. A jabiru at 3000ft is about 5 minutes, a RV-6 at 5000 ft again about 5 minutes.... Link to comment Share on other sites More sharing options...
Oscar Posted February 24, 2014 Share Posted February 24, 2014 No, it's also the available options. In the Jab. ( or Lightwing, Pipistrel, Tecnam etc) you have a radius of options available because of the 'here to there' flight profile that is considerably more than the RV6 even at 3,000. What the author has said is that at 3,000 in an RV6, you have bugger-all options, just pick a spot that is possible and go for it at 80 kts. - and NO LESS than 80 kts. And that means that you have to have a field that is big enough to get over the fence at 80 kts and wash off your speed before the other fence comes up - in a slippery aircraft. Paddocks like that are dime-a-dozen out west of say Narromine, or Dalby, or Tocumwal; try to find them on the coastal route from Sydney north or south.. For the USA, Ohio maybe has those sort of fields; I suspect they are pretty sparse in Colorado or Utah or Oregon or Washington State... Link to comment Share on other sites More sharing options...
winsor68 Posted February 24, 2014 Share Posted February 24, 2014 I would add RV3s to that equation too... http://www.atsb.gov.au/publications/investigation_reports/2000/aair/aair200000885.aspx Link to comment Share on other sites More sharing options...
Oscar Posted February 24, 2014 Share Posted February 24, 2014 I would add RV3s to that equation too...http://www.atsb.gov.au/publications/investigation_reports/2000/aair/aair200000885.aspx Yes, it's the same fundamental engineering problem. In a low-wing aircraft, there is an entirely obvious 'hinge-point' for forces at impact: the wheels attach to (or close to) the mainspar, the engine mount has to be reacted out to the mainspar, draw the lines and see how they interconnect. In a high-wing aircraft, there is a triangle formed by the mainspar, the engine mount and the main wheels. In the latter type, the pax's ( in a twin rather than a tandem), anyway) sit inside that triangle.) To get an equivalent level of secondary safety in a low-wing aircraft, you have to make the structure strong enough to resist the 'out-of-triangle' forces. The smaller the aircraft, the bigger the hole you have to provide in the 'cylinder' that is the fuselage, for pax. access. There's a damn good reason that the 'hole' for the pax(s) on fighter aircraft is really, really small compared to the size of the fuselage, and it's strength, not that the designers were sadists.. Link to comment Share on other sites More sharing options...
metalman Posted February 24, 2014 Share Posted February 24, 2014 Yes, it's the same fundamental engineering problem. In a low-wing aircraft, there is an entirely obvious 'hinge-point' for forces at impact: the wheels attach to (or close to) the mainspar, the engine mount has to be reacted out to the mainspar, draw the lines and see how they interconnect. In a high-wing aircraft, there is a triangle formed by the mainspar, the engine mount and the main wheels. In the latter type, the pax's ( in a twin rather than a tandem), anyway) sit inside that triangle.) To get an equivalent level of secondary safety in a low-wing aircraft, you have to make the structure strong enough to resist the 'out-of-triangle' forces. The smaller the aircraft, the bigger the hole you have to provide in the 'cylinder' that is the fuselage, for pax. access. There's a damn good reason that the 'hole' for the pax(s) on fighter aircraft is really, really small compared to the size of the fuselage, and it's strength, not that the designers were sadists.. Things I know 1, I have a few hours in RV6-7's 2, I've done quite a few glide approaches in RV's 3 ,I know that ( regardless of the writer you've referred to) an engine at idle does NOT produce an airflow over the tail, in fact it's a big draggy disc, 4 , I have a real good mate who has built and test flown approx 20 RV aircraft ,I have had this conversation and he has dead sticked them with out problems,,,yes sixes and sevens 5 , in any aircraft if you get to slow regardless of whether the engine is going you should have adequate air beneath you,,,or you may die with the stick held firmly in your belly 6, I know the report your referring to ,it was one RV6 and one RV4( I think) 7, I know the writer of the report 8 ,I know he has been offered a flight in an rv6 to see what it's like with the engine off 9, as far as I know he has not taken that offer up 10, the writer of the Oz accident reports talked to Vans about the RV6 , and Vans didn't think one accident warranted changing the airframe( quietly or not , the RV 7 is almost identical through the cabin sides, only dimension changes) 11 ,the writer of the article your referring to is ,,,,,,who,,,,,,what makes him an expert? 12, 80kias is not the best glide in an RV 6 or 7,but regardless the elevator will work the same at 80kias whether the engine is at idle or not, at 80 it will be windmilling anyway so the same drag penalty applies Matty 1 Link to comment Share on other sites More sharing options...
motzartmerv Posted February 24, 2014 Share Posted February 24, 2014 Thats the one Oscar. Im 90% sure it was the right wing that subsequently failed during the forced landing. The left wing broke both front and rear spa connections. I think. It was a few years ago and i never saw the wreck. So dont quote me. Link to comment Share on other sites More sharing options...
Ignition Posted February 24, 2014 Share Posted February 24, 2014 Vans quietly adopted (well, put out a similar) cockpit strengthening mod as the Australian one and I believe made it standard on all kits many years ago. But the aerodynamic problem that leads to the hard hit is very real: suggest you read para 6 of this: http://www.sdsefi.com/air44.htm Care to provide a link to the Service Bulliten for this apparent RV-6 cockpit strengthening mod? That link you provide is interesting too... How much experience did the pilot have in RV's? Its all well and good to provide a story, but a story is just that without context; as Mat says above, who is the author and what makes him an expert? 2 Link to comment Share on other sites More sharing options...
kaz3g Posted February 24, 2014 Share Posted February 24, 2014 ..The right wing snapped right down the middle. It seemed (from what I was told, I never saw it) that the crack propagated out from the fuel tank hole and cracked off beautifully in an apparent shearing load. It was assumed that the impact of the forced landing was not enough to cause the snapping of the wing, so therefor must have been an undetected issue from the previous accident. Im sure Jab would have some records on this incident if you want to check out what became of it. Im not sure myself as the satellite school have now gone on their own way.. Cheers No doubt such things will show up more frequently when CASA introduces SIDS for everything that flies. Kaz Link to comment Share on other sites More sharing options...
metalman Posted February 24, 2014 Share Posted February 24, 2014 No doubt such things will show up more frequently when CASA introduces SIDS for everything that flies.Kaz Such a sad thought Kaz, antiques will be cheap as,,,,but we won't be able to fly them 1 Link to comment Share on other sites More sharing options...
Oscar Posted February 24, 2014 Share Posted February 24, 2014 Merv - that's really, really bizarre - wish we could see the view from the other side. I don't mean to be combative here - but the 'break' line on the port wing is so extremely clean, and noticeably at the level of the water surface - and that water is very, very opaque. The glass used (certainly in the solid wings) is a biaxial 90-90 glass laminate laid at 45 degrees to the spar, so a spanwise tear would be jagged. Did you have a report that the wing had torn spanwise? - (that appears to be well behind the spar line). The starboard wing appears to be fairly normal in that piccy; the later failure MAY not have been a result of the earlier one - though any wing that is repaired is suspect unless you have explicit details of the damage and the repair scheme. That said - repair of a 'glass laminate is documented to be 100% 'as good as new' - PROVIDED that the proper techniques are used. Same goes for any material, really, it's just a case of how much 'repair' is needed. 1 Link to comment Share on other sites More sharing options...
motzartmerv Posted February 24, 2014 Share Posted February 24, 2014 The prelim report for the tiger that pranged a few months back is out now. More fuel to CASA's aging aircraft fire..:( 1 Link to comment Share on other sites More sharing options...
motzartmerv Posted February 24, 2014 Share Posted February 24, 2014 No sorry oscar, I didn't have anything on it. It wasnt with my school when either of these prangs occurred so im only going on hearsay. But donnie (the CFI) said jab found it a very odd failure as wel and they replaced the wing as part of the repairs. The insurance company gave them stick over it, but I think it was eventually sorted. The pic was taken after it had been skull dragged up the bank. Link to comment Share on other sites More sharing options...
Oscar Posted February 24, 2014 Share Posted February 24, 2014 Matty, too many points for me to make any clear answer, and I have no idea of the qualifications of the guy who wrote the USA report. However I certainly know the guy who did the cabin strengthening mod for the RV6 and prepared the expert opinion on the crash for the Coroner's report. He happens to be an aeronautical engineer with a number of type certifications to his credit, an ex-DCA/DoT crash inspector for part of his career, and a (still) CASA-endorsed test pilot. Vans certainly did NOT admit any fault (would you expect them to?) but DID make similar changes to the Australian mod. Care to provide a link to the Service Bulliten for this apparent RV-6 cockpit strengthening mod?That link you provide is interesting too... How much experience did the pilot have in RV's? Its all well and good to provide a story, but a story is just that without context; as Mat says above, who is the author and what makes him an expert? The RV6 is an Experimental - therefore no SB. However, you ought to read (read all tabs): http://www.atsb.gov.au/publications/investigation_reports/2000/aair/aair200005572.aspx I have NO idea about the US pilot. I can only suggest that you draw your own conclusions/ do your own research if you are thinking of owning / flying in an RV6 - I have no interest there. I don't like /dislike them, I'm just not very interested in them. I do know that the failure described in the ATSB report happened and the pilot's head was smashed as a result. 1 Link to comment Share on other sites More sharing options...
Ignition Posted February 24, 2014 Share Posted February 24, 2014 The RV6 is an Experimental - therefore no SB. However, you ought to read (read all tabs): http://www.atsb.gov.au/publications/investigation_reports/2000/aair/aair200005572.aspx I have NO idea about the US pilot. I can only suggest that you draw your own conclusions/ do your own research if you are thinking of owning / flying in an RV6 - I have no interest there. I don't like /dislike them, I'm just not very interested in them. I do know that the failure described in the ATSB report happened and the pilot's head was smashed as a result. http://www.vansaircraft.com/public/service-rv6.htm - Service Bulletins for the RV-6 can be found here - Vans actually do release SB's, and on everything I have searched through, I find zero references to Vans "quietly adopting" any mods similar to what you speak of. Well, I can find a few issues with the techniques and things he says, but I will reserve my comment on those in order to remain on topic. In my opinion, RV's are very safe and strong aircraft - when operated right. Interesting ATSB report there too: "Examination at the accident site revealed that the aircraft struck the ground while banked about 90 degrees left, and descending at an angle of about 34 degrees." - I cant imagine that being comfortable with many aircraft. 1 Link to comment Share on other sites More sharing options...
metalman Posted February 24, 2014 Share Posted February 24, 2014 I would call that a stall and wing drop,which would be really hard on your head if the ground is too close regardless of the aircraft. Oscar, I get your not that interested ,,,,but rather than post stuff that's either not true, plain wrong, of suspect source perhaps a bit more research,,,,I am interested,,enough to be building a six ,,,,and have done plenty of research, including having a face to face conversation with the afore mentioned engineer, flown a few different RV's , and scoured the net for issues,,,,and as ignition pointed out Vans have an extremely good system for making mods or SB's to their kits,,,,none of which are ever done quietly,,,as for an Australian mod, I'm on a few RV forums here and over seas and have yet to hear of such a mod with any endorsement from the factory( or infact without it),,,,and if you'd done just a little research you would be found Vans to be very active in making their aircraft safer,,,, Link to comment Share on other sites More sharing options...
Oscar Posted February 24, 2014 Share Posted February 24, 2014 Matty, I'm not knocking Vans, obviously they produce many very good aircraft. And the Vans site is extremely informative, Vans obviously takes pride in what it does and provides great support to its customers - absolutely no argument. However, I don't think it's accurate to call the ATSB report 'suspect'; it's not my opinion, it's the ATSB opinion. However, to keep this thread on track, let me reiterate my earlier comment: draw your own conclusions / do your own research. You obviously have and are satisfied, that's fair enough. I assume you've seen this article: http://rvbuildershotline.com/articles/accidentrate.html. It makes a very good case for the safety record of Vans aircraft, it also provides some reasonable analysis of the actual fatal rate for the various models. 2 Link to comment Share on other sites More sharing options...
Guest jabiru Posted February 25, 2014 Share Posted February 25, 2014 http://www.bordermail.com.au/story/2110842/myrtleford-man-thankful-for-a-lucky-escape-pictures/?cs=11 And this is the Pilot story in todays paper. Link to comment Share on other sites More sharing options...
Oscar Posted February 25, 2014 Share Posted February 25, 2014 Well, I think we have to put this one down as another Jab engine failure - it completely failed to not get him all the way to the accident site.. I reckon that's as good a 'Bugger' moment as one is likely to walk away from.. 1 Link to comment Share on other sites More sharing options...
poteroo Posted February 25, 2014 Share Posted February 25, 2014 Matty, I'm not knocking Vans, obviously they produce many very good aircraft. And the Vans site is extremely informative, Vans obviously takes pride in what it does and provides great support to its customers - absolutely no argument. However, I don't think it's accurate to call the ATSB report 'suspect'; it's not my opinion, it's the ATSB opinion. However, to keep this thread on track, let me reiterate my earlier comment: draw your own conclusions / do your own research. You obviously have and are satisfied, that's fair enough. I assume you've seen this article: http://rvbuildershotline.com/articles/accidentrate.html. It makes a very good case for the safety record of Vans aircraft, it also provides some reasonable analysis of the actual fatal rate for the various models. Yes, that's a fair enough story on RV safety. I think the numbers of RV4 and RV6 models involved has much to do with the early builders having used older, (often 'on condition') engines, whereas builders of RV7 and RV9 series have been obliged to buy new engines. As well, and probably more importantly, earlier builders didn't have access to sound training on RV types. Today, they can easily obtain instruction in the US, thanks to the FAA waiver allowing instruction by a CFI in the CFI's own experimental RV. When the early RV's flew in the 90's - the collective knowledge of RV flying characteristics was all in Vans' head. Sure the RV6's are just a bit edgier to fly than the 7's and 9's - but they are, IMHO, safe for a prudent pilot. It could be that the high RV6 rate has more to do with low time pilots trying to do 'fancy' wheel landings - rather than a plain 'bread & butter' three pointer. The lower speeds and more rapid deceleration with the fully stalled three pointer increase safety....lots! You just need to round out accurately - meaning practice. Pilots need to stay in practice on RV's. The high rates of descent discussed earlier have lots to do with the propeller fitted - a coarser pitch will glide better. Each aircraft, being handmade, is a little different. happy days, Link to comment Share on other sites More sharing options...
geoffreywh Posted February 25, 2014 Share Posted February 25, 2014 Anybody know what brought the Jabiru down......(other than gravity of course) Link to comment Share on other sites More sharing options...
motzartmerv Posted February 25, 2014 Share Posted February 25, 2014 The article said he was attempting to land in his mates paddock, but undershot the approach. Hit a colvert. 1 Link to comment Share on other sites More sharing options...
alf jessup Posted February 25, 2014 Author Share Posted February 25, 2014 Anybody know what brought the Jabiru down......(other than gravity of course) Engine was purring like a kitten right up until it poleaxed the culvert I would say, You would have to assume human error was at fault on this one, best part is the pilot is alive with no real injuries and it once again shows that Jab do make an outstanding airframe with the best possible survival cell of all LSA's. Alf 3 Link to comment Share on other sites More sharing options...
motzartmerv Posted February 26, 2014 Share Posted February 26, 2014 Sounds like it should have been roaring like a lion, and getting the hell out of there!!!...:) 4 Link to comment Share on other sites More sharing options...
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