Guest Perry Posted January 14, 2007 Share Posted January 14, 2007 Folks, I found this really informative report recently released by the ATSB regarding a spate of microlight accidents. I read the structural analysis of the wing failures with great interest and got a real wake-up call on the effects of negative-g loading on wingtips! This is really useful stuff: http://www.atsb.gov.au/publications/investigation_reports/2006/AAIR/aair200601173.aspx Link to comment Share on other sites More sharing options...
eastmeg2 Posted March 14, 2007 Share Posted March 14, 2007 The Jan06 Streak-III wing failure with the outboard wing spar breaking upwards and backwards sounds consistent with the wing exceeding its G limit loading. There were apparently eyewitness reports of it being in an out of control spiral dive. Link to comment Share on other sites More sharing options...
bushpilot Posted March 15, 2007 Share Posted March 15, 2007 Was there any feedback from the observers on what caused the 'out of control spiral dive'? i.e. induced by deliberate maneuver that went wrong? Link to comment Share on other sites More sharing options...
eastmeg2 Posted March 19, 2007 Share Posted March 19, 2007 I don't think it is appropriate to be specific about what I've heard 2nd hand until the official report is released, risk being booted off this web forum, or worse. March 07 RAAus magazine has promised write ups of so-far-unresolved accident investigations in near future editions. The trike in question was RAAus registered. I can say that I personally don't believe that the accident will be attributed to any mechanical or design problems with the trike, and will come down to a series of events that led to the wings ultimate design loading being exceeded. Sorry. Link to comment Share on other sites More sharing options...
Guest Crezzi Posted March 19, 2007 Share Posted March 19, 2007 I can say that I personally don't believe that the accident will be attributed to any mechanical or design problems with the trike, and will come down to a series of events that led to the wings ultimate design loading being exceeded. Sorry. Thats my belief too. I look forward to reading more in a future mag but I suspect that it might not contain any information than the ATSB report. I have to say that I'm not terribly impressed with the feedback on accidents in Aus. I don't know if its because of legal constraints, the quality / quantity of pilot submitted reports, the mag being on sale to the public or something else. John Link to comment Share on other sites More sharing options...
Guest Andys@coffs Posted March 19, 2007 Share Posted March 19, 2007 Those that fly trikes would generally understand that there arent that many "normal" maneouvers that generate neg G loads on the wing other than the transient thermally induced flying loads. The one that I was always told was an absolute no no, and one that would generate neg G loads if it went wrong was an attempted loop. Now that comment is simply me talking about the things I know to have cause neg G, and negative life in the past, not the specific accident that was being discussed in this thread. There are videos on the net of the unstable rotations that follow a failed loop attempt in a trike. I believe, perhaps coincidentally, that in that video the wing also fails before it hits the ground. My instructor sent this to me not long after I went solo. You can see it here Andy Link to comment Share on other sites More sharing options...
bushpilot Posted March 20, 2007 Share Posted March 20, 2007 Gosh! That clip got the sweaty hands thing going - just watching it! A good lesson indeed. In my 3 axis GA days, I would regularly do hammer-head stalls for fun in a Piper Colt - but I tend to just putter around in the trike; no point pushing the envelope; but great fun nonetheless - just choofin around sniffin the flowers (from about 1,000')... Link to comment Share on other sites More sharing options...
Guest Crezzi Posted March 27, 2007 Share Posted March 27, 2007 Attempting to loop is one very predictable way to generate neg G loads but certainly not the only scenario. You might find the following accident reports from the UK interesting - http://www.aaib.gov.uk/publications/bulletins/january_1997/mainair_501010.cfm http://www.aaib.gov.uk/publications/bulletins/may_2000/gemini_501646.cfm The AAIB website has info on quite a few microlight accidents - try searching on Pegasus or Mainair. They generally only get involved in serious accidents though - as here, the national microlight organisation (BMAA) handles most of them. John Link to comment Share on other sites More sharing options...
Guest Andys@coffs Posted March 27, 2007 Share Posted March 27, 2007 John Those reports, especially the 2nd. were interesting reads. From my perspective if I attempted a loop and it went wrong then the outcome was clearly my fault for choosing to go beyond manufacturers limits On the otherhand to be flying along, encounter a downdraft and have the wing fail within a time frame that the pilot was unable to do anything about is plain scary. It would seem that flying a flash2 wing is anything but a flash idea. Regards Andy Link to comment Share on other sites More sharing options...
Guest Crezzi Posted March 27, 2007 Share Posted March 27, 2007 You're not wrong but the report is at pains to emphasise that it was that particular wing not necessarily the design. I lived in the UK at the time and owned a trike of that type so I was particularly interested in the outcome. It resulted in a mandatory "before-next-flight" inspection of all the Flash wings specifically checking the length of the luff lines. The bulletin specified both maximum and minimum limits for the amount of reflex - a lot of trikes (including mine) technically failed as they had too much which was the opposite of the suspected cause. Grim reading though - fly safe ! John Link to comment Share on other sites More sharing options...
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