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Dafydd Llewellyn

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Everything posted by Dafydd Llewellyn

  1. Thanks, Kaz. This might be an appropriate point for a little history lesson: In 1993, the Howard Government had, in its election platform, the introduction of an "American-style experimental category" into the Australian Civil Aviation Regulations; the SAAA and AOPA had been pushing for this, for decades. The Howard Govt got into power in 1994; and in 1996 the then Minister, John Sharp, set up the Review of Regulations; and one of its marching orders was to make good that election promise. The American Experimental "category" exists because the U.S. constitution gives the individual the right to elect to take a risk, if he so chooses. Australians wanted that same right, in regard to recreational aircraft. The US experimental "category" appears in FAR Part 21, regulations 21.191 thru 21.195. (They are, nowadays, in the same place in CASR Part 21). However, Australia did not have a Part 21 in its regulations in 1996, because the people who wrote Australia's CARs did not dream that anybody here would be so silly as to to actually build an aeronautical product; the regulations were written about importing such products and maintaining them. (Oh, there were a couple of makers of wood propellers, but they were covered by ANO 108.28 and 108.29-which still exist, by the way). The whole thrust of the CARs was paternalistic - protecting people from themselves, whether they wanted this or not. This was almost a religion within DCA/CAA/CASA; and the problem was (and still is) that the experimental provisions turn that completely upside down; they are based on voluntary acceptance of risk - just as is slowly becoming recognised for any "inherently dangerous" recreational activity, as is shown by the precedents set in NSW by Campbell Vs Rodney Victor Hay, and Echin vs STGC. So we have this little "bubble" of rebellion (or freedom, take your pick) buried inside a vast body of wholly paternalistic regulations that are fundamentally designed to protect Auntie Flo when she flies off to visit her grandchild. Some people have difficulty in grasping this temporary reversal of gravity as one passes across this little section of the CASRs. So ANY aircraft that is essentially "experimental" in nature - however disguised by an E24 or a 19 registration, or by any other means, should have a prominent placard stating that it does not comply with normal aviation safety standards, and persons flying in it do so at their own risk. (I wanted the words "Abandon hope all ye who enter here", but I was overruled, and the message is toned down more that I think it should be, but a message is required to be there). This also necessitated that CASA be given an immunity to negligence in regard of these aircraft, in the form of CASR Part 201.003. The message has not yet fully seeped through to the courts (edited - Mod) - or, indeed to the drafters of the Jabiru engine Instrument, in that they included experimental aircraft. But it is quite clearly evident in CASA Advisory Circular 21.10; and anybody who is still having trouble with the whole idea should read that AC. (edited - Mod) Some manufacturers in the U.S.A. wanted to be able to sell what amounted to sub-standard aircraft as fully-manufactured products rather than as 51% rule kits; so they sought a half-way house - the first attempt was the Primary category; but the sole example with an FAA primary category TC was (and still is) the Australian Seabird Seeker. So they tried again, and the "consensus standard" put out by the ASTM was the result - and this made things a lot simpler for new entrants to this manufacture industry; but make no mistake, these are sub-standard products with a limited imprimatur, and limited application. They are only a whisker above experimental, and if you modify them without the manufacturer's consent, (or if the manufacturer ceases to exist) they revert to experimental.
  2. All true - but probably not relevant. Basic reason for V engine.
  3. Multiply the pressure load by the leverage ratio of the "ears" of the cylinder flange; it's not a direct load path. The flexure of the flange also puts bending into the bolts.
  4. This is CASA you're talking about, remember. Jabiru holds the Production Certificate, so it's Jabiru they talk to. Q.E.D.
  5. Camit make (to order) either an experimental "core rebuilt" Jabiru engine; or a CAE experimental engine. They are the same thing, physically, because it is cheaper for CAMit to repair the Jabiru engine by 100% "repair by replacement", than to reclaim parts from an existing engine. What that means is that when you take your old engine in, the whole thing goes into the bin, and what you get is 100% new parts. If you simply order a CAE engine, there's nothing to put into the bin - that's the difference. You can check the details with CAMit, but that's my understanding.
  6. I've been pointing out the risk of this for some time. If I had a -D model Jabiru, I'd be ordering a CAE engine for it and shifting it to E24 registration ASAP.
  7. Pardon, but are you not confusing cylinder head cracks with cylinder base cracks? Or have I missed something? No, as far as I know, Jabiru is not working with CAMit; and moreover, CASA have not made any contact with CAMit since this draft Instrument was issued, other than to verbally confirm that the Instrument did not apply to CAE engines.
  8. You forget that the British industry was working on Government contracts - and there was a war looming. Jabiru has neither of these minor circumstances to help it.
  9. They could hardly be inferior, since CAMit make the originals - apart from outsourced parts.
  10. Do you not understand the difference between an engine made to one set of drawings and specifications, to one made from a different set? The Jabiru 2200 C, I say again (and again and again) has a Type Certificate issued by CASA. That TC refers to a specific Master Drawing List (it's on page 4 of the TCDS). Every Jabiru 2200C engine made by CAMit has to conform to that Master Drawing List; and CASA manufacturing division make sure it does, down to the last detail. Much the same applies to the other Jabiru engine models made by CAMit. All those engines have a Jabiru data plate. The CAE core-rebuilt engine is a Jabiru engine with modifications; there is a master drawing list for those modifications. It has a Jabiru data plate plus a CAE modification data plate, to specify the modification status. It looks virtually identical to a Jabiru engine, apart from the alternator. CAMit were also scratch-building essentially the same thing as the core-rebuilt engine, but not starting from an existing Jabiru engine, and that has only a CAE data plate. Because of the obstructions, these versions will now not be taken to certification, as far as I am aware. I assume they will continue to be built to order as experimental engines. Ian Bent is now concentrating on an engine that cannot be claimed to have any conflict with Jabiru IP. The intention - if it can be realised - is to take that engine through ASTM 2245. I can't make it any simpler than this. Dafydd I know you had said that but as everyone keeps quote regs on here I was looking for something in writing. So is Ian Bent. It's only verbal from CASA so far; we're all waiting.
  11. I suggest you go and see what Ian Bent has been doing (except he's frantically busy right now, with this undeserved crisis to his situation) - you'll find he's light years ahead of this discussion.
  12. Did the Harley have a starter of the modern form, in which the solenoid pulls the gears into mesh before it makes electrical contact, or was it a simple Bendix gear that threw-in by inertia? There's a considerable difference in the impact torque, I think you will find.
  13. I doubt it is significant - but I agree, the ring gear would be much better located at the front of the engine, at least on the 3300, but not for the reason you suggest; it should preferably be where its mass adds to the propeller flywheel effect, not to the flywheel effect at the opposite end of the crankshaft. I've said all this before, several times. This should not be taken to mean that I consider the current location to be a design fault; it would be a desirable design improvement, which is not the same thing.
  14. In regard to what? As far as the through bolts are concerned, it's got nothing to do with torsional resonance (tho there might be some "bowstring" resonance in the Jabiru design, I've not looked at the detail for a while); but everything to do with a number of factors that accumulate to cause loss of pre-load; and also to flexure of the cylinder base flange (take a good look at the cylinder base flange design on a Lycoming - they had trouble there, too). Every time a cylinder fires, the force trying to pull the cylinder base away from the crankcase is about 3.5 tons. Things flex under that sort of hammering. As far as the "flywheel" bolts on the 3300 are concerned, I suspect it does contribute - and that can be improved considerably by removing the permanent magnet rotor from the engine - which reduces the moment of inertia of that end of the crankshaft assembly - and replacing it with a belt-driven alternator, which does not contribute to the "flywheel" inertia, but instead supplies some dynamic damping at the torsional frequencies likely to be responsible. The propeller is the principal "flywheel" and its attachment MUST be capable of handling the transient loads that involves - just as in any direct-drive Lyconental. So putting a Rotax donut between the crankshaft and the propeller is right out. It works (for a while) in the Rotax because the individual firing impulses are relatively small, and at twice the frequency. The Rotax gearbox pinion would fail very quickly without some sort of cushioning effect between the crankshaft and the propeller.
  15. 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.
  16. 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.
  17. 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.
  18. Think about that; neither position is actually sensible. No matter what improvements are made to the engine, the failure rate can never be zero; therefore there will always be the chance that somebody will die. That's WHY the courts have defined flying in recreational aircraft to be an inherently dangerous recreational activity. If the aircraft were required to be able to stay aloft when the engine dies, a criterion of either of those sorts might look feasible; but in reality even that does not do it. A more logical approach would be to establish an engine "safe life" as being the time-in-service that corresponds to some arbitrary statistical failure probability; however the probability cannot be zero; for a transport-category aircraft, ICAO sets a target probability of a catastrophic accident as (if my memory serves me) one in 100 million per flying hour. The rate gets higher as you come down the scale from that. There is an exponential correlation between the average time-in-service to major failure, and cost. In a recreational situation, we normally accept a higher risk, in order to get a lower cost. The problem is that the average TIS to major failure cannot be established, in the real world, before the aircraft goes into service. It's not realistic to demand that the manufacturer runs a statistically-significant sample to destruction in order to establish this - because there is not way such a test can cover all the variables introduced by the users and maintainers. The ASTM standard allows the manufacturer to set the TBO at five times the endurance test hours, for a single test specimen. You want better than that, you are outside the recreational area, pal. It follows that the manufacturer needs the latitude to introduce modifications on the basis of service experience, because there is no other practical way to improve the reliability. That is the reason why the regulations talk about Service Bulletins. But litigation inhibits that process, so it is fundamentally counter-productive for the majority of users. Contrary to what a number of people have alleged on this site, I know enough about Jabiru engines to say that Jabiru have never stopped developing their product; in fact, that is becoming part of the problem, because the engines in the field are at all stages of development, they do not all get upgraded every time there is a SB, and you find engines in service with different mod. standards from one cylinder to the next. I am not by any means saying that this process has always had a beneficial effect; it's arguably been a bit of each; but not for want of trying.
  19. Curse the software; I could not finish my post. Here goes again: All right, out of all this shouting & tumult, what do we have? Let me see if I can summarise it: 1. We have a statistic - not necessarily a very good-quality statistic, but still, it's about all we currently have - of one engine failure in around 3300 landings - i.e. 0.03% of movements. Roughly a probability of one in a thousand per flying hour. 2. As a result of this statistic, plus a lot of noise from certain persons, RAA demanded action from CASA. In so doing, it is arguable that RAA did not consider the statistic in the proper context of the other statistical risks that apply to any recreational aircraft to a greater or lesser degree; they merely saw that the Jabiru statistic was not as good as that for the Rotax 912, realised their impotence to do anything constructive about that, and lodged a rather unthinking complaint. 3. CASA over-reacted, causing panic amongst Jabiru owners and operators, and degrading the resale value of their assets; the total financial loss is likely to run into tens of millions of dollars. To a monkey with a hammer, everything looks like a nail. 4. Many owners have de-registered their aircraft, and many have resigned from RAA, which in all probability threatens to cause RAA to collapse. 5. There are persons who may have a valid grievance, who have either launched or threatened legal action against Jabiru, and who are still making a lot of noise, which may or may not result in a class action against Jabiru. These people are, it would seem, out for blood, and do not care what the collateral damage may be. 6. The threat of any such action can only have the result that Jabiru will resist all claims that their product is defective; to do otherwise would be to admit liability, which would be suicidal. 7. The collateral damage will be that the Jabiru owners who would simply like the probability of an engine failure reduced from 0.03% per movement, to perhaps 0.015%, are most unlikely to have that available from Jabiru. 8. CAMit (CAE) can provide that sort of improvement, but they are hamstrung by their dependence on the ongoing income from manufacturing about ten Jabiru engines a month for Jabiru, to Jabiru's design. If Jabiru folds, CAMit folds. So the collateral damage will also prevent any "fix" from CAMit. 9. Aircraft having either E24 or 19 registration, or VH experimental, are free to fit a CAE engine. In any case, the inclusion of experimental aircraft in the CASA draft Instrument is invalid, and can be expected to be removed. (RAA could do something useful by trying to hasten this). 10. The CASA personalities involved very likely have their back so the wall, with Ministerial "please explains" to answer - so they are likely to do everything possible to justify their actions. So, in summary, we have a completely stupid situation on all sides. It is not constructive to point fingers at this stage, it's far too late for that. This is a lose-lose situation. Either the rock or the hard place has to back off. To quote Mark Twain: "I wish I loved the human race; I wish I loved its silly face; And when I'm introduced to one, I wish I thought "What jolly fun."
  20. All right, out of all this shouting & tumult, what do we have? Let me see if I can summarise it: 1. we have a statistic - not necessarily a very good-quality statistic, but still, it's about all we currently have - of one engine failure in around 3300 landings - i.e. 0.03% of movements. Roughly a probability of one in a thousand per flying hour.
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