turboplanner Posted November 21, 2014 Share Posted November 21, 2014 Grounding the fleet is one of the most inappropriate statements I've heard. Sorry Turbs. Have YOU ever flown any two stroke powered planes? . I cannot see the" operators of jabiru" people as those who must be saved from themselves because they don't have proper concerns about safety. As a group THEY more than any other want to operate safely. They probably just want some straight talk and facts as to how to make steady improvements and evaluate what the real risk is.The engine(s) will be gone IF we don't utilise the current manufacturers in any process of improvement/change. If you are just going to "dump" the engines, how do you reconcile that action with those who have had a perfectly good run out of them? Most of those have left this forum long ago because of the negativity and over the top expressions used, in regard to the plane they fly. (Don't shoot ME I'm only the messenger here) In NO WAY do I wish to stand in the way of making changes happen. Quite the opposite..IF we just close the shutters we seal the fate of the engine(s). In other parts of the world they must wonder what we are on here sometimes. Nev. The fleet isn't being grounded according to CASA FH, I was asked a question a few weeks ago and I gave an answer on what I would do, which co-incidentally would allow zero forced landings and zero fatalities from forced landings. So there's point dwelling on what I would do because my post carried no more weight than anyone elses. What you have to focus on is what CASA decides to do. Fixing the problem quickly and moving on quickly is what I've done for the past few decades, after I found that screeching outrage didn't wash. No, I've never flown a two stroke, so I would have to be trained, but I did work on two strokes (air cooled) for twelve years destroying a few dozen pistons and eventually producing engines putting out roughly double their original power with about the same reliability as four strokes. I think I know where you're going but can't think of any ongoing engine issues right now. I've never recommended dumping engines, I've suggesting fixing them with minimal delay. how do you reconcile that action with those who have had a perfectly good run out of them? That's a red herring discussion regarding the current CASA action which is about safety. In this case CASA are referring to an increased risk. If you want to talk about cost of operation, that doesn't belong in this thread. However, some people have been using their experience with one, two or four etc aircraft and trying to impose their views on others If one engine gets to 1000 hours and another gets to 10 hours, then the fleet average is 505 hours Getting away from brand names, if an engine has a common fault which occurs around 500 hours, then it is economical to fit a new part at say 450 hours, and you can argue there is not a safety issue. On the other hand, if an engine has a common fault but it can occur from 2 hours to 1800 hours or anywhere in between, it's not predictable, so if you did 50 hours a year, and had a failure at 800 hours, you may have owned the aircraft for 16 years, and you may have been able to say "My" engine had been totally reliable, up to the failure, but in a random situation it's wrong to say "the engine", meaning everyone's engine is not going to have a problem before 16 years. Just a question of how you report mathematics. 2 Link to comment Share on other sites More sharing options...
Dafydd Llewellyn Posted November 21, 2014 Share Posted November 21, 2014 Summarising the multiple threads pertaining to this topic over the last week, the following actions seems to be how all of these developments have unfolded: 5. For some time Jabiru Aircraft & Camit have not been working together on the "same page" with each other which have created tensions between both of these Companies ( which are both good genuine Aussie Companies"). 6. In the meantime if Jabiru Aircraft & Camit can come to together as grown men & forget their differences & sit around a table to work out a viable Commercial Joint Venture for the financial benefit of both Companies in the future, then should this Joint Venture eventuates, then Jabiru Aeroplanes will be kept flying around the world & at the end of the day would in all probability be to CASA'S satisafaction. CAMit and Jabiru started off very much in the spirit of a joint venture; the reasons that went sour are long, and not anybody's business but the principals concerned. CASA does not, I suspect, have the engineering expertise at its fingertips to get to the root of the through bolt issue. Just "make them stronger" isn't the answer; and CASA does NOT supply an engineering consulting service. CAMit does have the answer, and wants to apply it commercially. Jabiru considers that it has in fact fixed the problem; and whilst this may very nearly be so, I doubt that it has really gotten to the root of the problem (my personal opinion). The photo on Post #462 shows why, if you have the engineering knowledge to interpret it correctly; but that is Ian Bent's IP and not for me to discuss on a public forum. CASA cannot compel CAMit to hand over its IP to Jabiru; and it cannot compel a joint venture. It can issue an Airworthiness Directive; it can also use the regulatory requirement of CASR 21.016 to impose special conditions, including operating conditions ( which is essentially what that draft Instrument was leading to). Either of these measures, unless applied extremely adroitly, will simply destroy both Jabiru and CAMit. The "bull in china shop" approach so far being applied, is not going to work. 1 2 Link to comment Share on other sites More sharing options...
turboplanner Posted November 21, 2014 Share Posted November 21, 2014 This is not consistent with reality. By all means, seek to reduce the risk; but there will always be a risk. Your argument above is, logically, also applicable to the risk for a Rotax 912 - except the the Jabiru at the moment takes precedence. The reality has been stated by 01mb precisely. What RAA has been doing, is not clearly stating the risk. Understand the risk; if you can't stand the heat, get out of the kitchen. I'm sympathetic to you because you were involved in the certification process, but once someone discovers an issue, we don't get the option to discuss the ultimate alternatives and solutions these days. In the prescriptive era, I used to discuss the risk, and put up arguments that in doing such and such we "minimised the risk, sometimes stating the obvious "there is always a risk" I can't do that these days. I don't believe RAA and CASA have to provide the detailed explanation you would have expected under prescriptive legislation, just the bald facts of a trend increase. As far as the last sentence is concerned you can probably go to the austlii site and find cases where that was said, and what the case decision was. Link to comment Share on other sites More sharing options...
facthunter Posted November 21, 2014 Share Posted November 21, 2014 One prang in the US , the dashpot slide stuck wide open. The carburetter is common to the Rotax too. This is not by way of a cop out but how you must refine comparisons, (since comparisons seem to be the decider here) I can't see that as being overly scientific. Nev Link to comment Share on other sites More sharing options...
jetjr Posted November 21, 2014 Share Posted November 21, 2014 For pnce i agree TP, your statement on numbers is right. Lots of owners consider a rebuilt engine @ 1000 hrs is acceptable, significant top end at 500 is regulalry done. They STILL stack up as solid investments. Some are running to 2000 hrs too even in training environment. the problem is the outliers like 20-200 hr failures, this needs attention no doubt. As Jabiru have stated if the throughbolt issue and valve failures are addressed it may be a very different picture What You are saying is that if TBO and top end overhaul hours changed everyone would be happy and the aircraft be safer? Thats how plenty look at their engines currently The core of the issue is that of Jabiru cannot afford to push ahead, owners will end up with NOTHING, no parts, no LSA. Amuses me people think Jabiru and any business are "raking in money" they are a very small family owned business. 6 Link to comment Share on other sites More sharing options...
turboplanner Posted November 21, 2014 Share Posted November 21, 2014 FH, sorry I forgot to say the current situation is not unlike the way you operate your Indian. In Victoria, Historic registration status allows you to operate without the latest braking systems etc, provided you comply with some rules, including operating on a log book for each use on a road. As I understand it there have been some issues with cars, and the system has been or is about to be tightened up substantially, I think eliminating some vehicles from the scheme. Link to comment Share on other sites More sharing options...
turboplanner Posted November 21, 2014 Share Posted November 21, 2014 For pnce i agree TP, your statement on numbers is right.Lots of owners consider a rebuilt engine @ 1000 hrs is acceptable, significant top end at 500 is regulalry done. They STILL stack up as solid investments. Some are running to 2000 hrs too even in training environment. the problem is the outliers like 20-200 hr failures, this needs attention no doubt. As Jabiru have stated if the throughbolt issue and valve failures are addressed it may be a very different picture What You are saying is that if TBO and top end overhaul hours changed everyone would be happy and the aircraft be safer? Thats how plenty look at their engines currently The core of the issue is that of Jabiru cannot afford to push ahead, owners will end up with NOTHING, no parts, no LSA. Amuses me people think Jabiru and any business are "raking in money" they are a very small family owned business. I also think that if the random through bolt issue and valve issue is solved the manufacturing issue virtually goes away. There's no point in changing TBO with a random-time fault because you might get it at 300 hours. I explained in an earlier post that from a manufacturer's point of view TBO can be varied for strategic reasons to optimise customer satisfaction (for example you might decide on 800 hours but offer free big end bearings), or you might bulletin a 400 hour offer of a fixed-time failure part with free parts and a free set labour fee - the marketing possibilities are endless. Link to comment Share on other sites More sharing options...
facthunter Posted November 21, 2014 Share Posted November 21, 2014 Yes I'm registered as an authorised inspector for that stuff. I imagine the Vintage and Historic aircraft would operate in a similar fashion. Nev Link to comment Share on other sites More sharing options...
dmech Posted November 21, 2014 Share Posted November 21, 2014 I don't think what side is of any consequence they are through bolts after all. It was oil filter side, broke off at base of nut. Tom Thanks Planesmaker we just need to see if there is any pattern to these bolt failures . we have found the resonance problem and eliminated about 90% of it in several jab engines , since then [18] months ago we have had no trouble 1 eng 800 hrs at least 2 others around 700 hrs all still operating, engines run smoother /50 deg cooler climb small increase in power, 200 hrs was about all you could expect out of these engines before a major repair, used in F.T.S . 2200 hydr lifter . the way the bolt has broken certainly indicates[ cyclic loading ] , even if they increased size to 5/8 would probably still fail. the base cause needs to be addressed, rather than just beefing up bolts , seems to be an Australian manufacturers trend, if it breaks , just make it bigger. Your bolt failure position and the other one I have ,ARE ALLREADY indicating a pattern that I suspect would be associated with this resonance . bit like the violin and glass trick. I'v been engine remanufacturing since 1976 full time , I have seen large diesels have ends break off cranks 4"diameter all because of resonance. So again , thank's for your reply. ALL other bolt failure position indications would help ANYONE !. Could be a goose chase , but who knows , has to start some where. A.D. 2 1 1 Link to comment Share on other sites More sharing options...
turboplanner Posted November 21, 2014 Share Posted November 21, 2014 It's like walking across the frozen river. Step out, test the ice: (a) No cracks = next step (b) bending but no cracking = next step carefully © cracking = no more steps, back inside to the fire (d) cracking and a she'll be right jump = OH Sh$t Link to comment Share on other sites More sharing options...
turboplanner Posted November 21, 2014 Share Posted November 21, 2014 Like that dmech, I was thinking the photo in a previous post of a through bolt didn't look like stretch, agree with resonance the diameter wouldn't make much difference, and the flywheel bolts also sound linked. Link to comment Share on other sites More sharing options...
motzartmerv Posted November 21, 2014 Share Posted November 21, 2014 . we have found the resonance problem and eliminated about 90% of it in several jab engines , since then [18] months ago we have had no trouble 1 eng 800 hrs at least 2 others around 700 hrs Hi. Can you give some detail re this resonance issue? How its caused, how you rectified it? 3 Through bolt failures we have suffered: 1. Oil filter side, front cylinder, top rear bolt 2, Front stud (off oil filter side) 3. off oil filter side, front pot, bottom rear bolt 2 failures on the same engine. Fly wheel attachment bolts failed in between through bolt failures. 1 Link to comment Share on other sites More sharing options...
facthunter Posted November 21, 2014 Share Posted November 21, 2014 I don't spend a lot of time on Jaba chat etc, but Jabiru have always emphasised the need to keep the top end up to scratch. You are making a Rod for your own back (Pun eh!) if you run one which is down on compression. That would apply to any aero engine.. I would want to have convincing good numbers for me to run much over 800 hours. I see that as a reasonable llfe for valves especially the exhaust. The parts are cheap. Link to comment Share on other sites More sharing options...
JimG Posted November 21, 2014 Share Posted November 21, 2014 Hi dmech, being in the engine re-manufacturing business myself, I am really interested in what steps your have taken to eliminate the resonance problems. I absolutely agree that the bigger bolts will still break in the long term or in the short term shift the problem elsewhere. The flywheel bolt failures are the first red flag for me and I really question the logic in changing from all wood to a composite propeller. JimG 1 Link to comment Share on other sites More sharing options...
facthunter Posted November 21, 2014 Share Posted November 21, 2014 Motz, I don't think we have really nailed the through STUDS thing as to the cause. Backfiring a late Holden V6 (ON GAS)will crack the block apart and the 6 cyl Falcon (GAS MOTOR). runs conrods out of the Turbocharged motor, that look like diesel ones. While we aren't running on gas there could still be some similarity. Certainly If a stud has gone I would strip the motor entirely. Nev Link to comment Share on other sites More sharing options...
turboplanner Posted November 21, 2014 Share Posted November 21, 2014 FH, What do you think about the resonance? Link to comment Share on other sites More sharing options...
motzartmerv Posted November 21, 2014 Share Posted November 21, 2014 The engine in question has four cracked heads, discovered through the latest SB. The stud wasnt a through bolt, it was one of the front studs that go to a dowel type thingy (technical term) Link to comment Share on other sites More sharing options...
facthunter Posted November 21, 2014 Share Posted November 21, 2014 Flywheel mounting Tubs? Nev Link to comment Share on other sites More sharing options...
turboplanner Posted November 21, 2014 Share Posted November 21, 2014 What do you think about the resonance? Flywheel mounting Tubs? Nev I was thinking about dmech's post #756 and added the flywheel bolts to it. Link to comment Share on other sites More sharing options...
facthunter Posted November 21, 2014 Share Posted November 21, 2014 I'm I agreement with him. I've harped on about resonant frequencies (harmonics ) for years. You only get away with wooden props on these motors.. The Sensenich composite started delaminating near the hub. I doubt they expected that.. Haven't we been assured there are no resonance problems in the normal rev range? That could account for the erratic oil pressure too. Nev Link to comment Share on other sites More sharing options...
Russ Posted November 21, 2014 Share Posted November 21, 2014 How about the fitting of a Rotax type donut under the prop.......just asking 1 Link to comment Share on other sites More sharing options...
Yenn Posted November 21, 2014 Share Posted November 21, 2014 Do we know how the failed engines were run. With one operator getting 3 failures, it would be good to compare his method of operation with other operators. 1 1 Link to comment Share on other sites More sharing options...
Dafydd Llewellyn Posted November 21, 2014 Share Posted November 21, 2014 I'm I agreement with him. I've harped on about resonant frequencies (harmonics ) for years. You only get away with wooden props on these motors.. The Sensenich composite started delaminating near the hub. I doubt they expected that.. Haven't we been assured there are no resonance problems in the normal rev range? That could account for the erratic oil pressure too. Nev No, that does NOT account for the erratic oil pressure. Firstly, fit one of the CAMit oil filter/cooler adapters; that gives the oil pressure relief valve a seat that does not jump about. Secondly, shift the oil pressure sender from the normal position to the front end of the main oil gallery, so it's not seeing the pressure upstream of the filter - which has its own by-pass valve - or the oil cooler - and you will see the pressure that is actually reaching the bearings - and it behaves quite normally, with those two things fixed. 1 Link to comment Share on other sites More sharing options...
turboplanner Posted November 21, 2014 Share Posted November 21, 2014 OK then Dafydd, leave the oil pressure out of it, what do you think about the resonance? Link to comment Share on other sites More sharing options...
Downunder Posted November 21, 2014 Share Posted November 21, 2014 Jabiru should have "gifted" camit the engines along time ago. Concentrated on the brilliant airfames, developing them further with better options (yokes?). Camit could have concentrated on and develped the engine with a known income in Jabiru airframes. Win win? Someone mentioned Jabiru as a "family business". That may have been an advantage early on but has fast became their achilles heal I think. I think Jabiru are making decisions based on emotion and sentimental attachment (how dare you say our engine is bad) instead of a defined pragmatic business approach..... 2 1 Link to comment Share on other sites More sharing options...
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