Oscar

JJ - the SDS kit is very impressive - but I think it doesn't have the capability to change distribution to each pot individually, or have I missed something? I think it's kind of one-step-further-removed from being an add-on idea, more a replacement.. and for those interested in taking that step, certainly worthy of major consideration.

It is difficult to disagree with that logic Oscar. The only remaining discussion is how you would practically and cost effectively achieve redundancy of the systems and the electrical supply.This is a very interesting discussion and I do particularly enjoy the humour of the parties involved.

 

I also have a particular interest in this area of engine science, most of my lessons building and destroying race boat engines were costly. LOL

By test, find out the fuel delivery profile using the cd carby only that delivers more or less reliably about, say 90% of the fuel required on average to keep the engine reasonably happy at say 75% power. Set the carby up to do that; needle, jetting. Then add Dafydd's idea of an auto-rich solenoid that simply fools the carby into delivering more than required if in abnormal situation i.e. EFI failure. Perhaps also modify the existing 'choke' function on the carby to provide 'climb-rich' condition, that one simply pulls on at the start of the take-off run and leaves alone until throttling back to cruise climb.

Then size the injectors adequately to provide all the additional individual pot supply in normal circumstances so that when everything is running happily, the added injector droplet size is an efficient fuel-air mixture. That is intended to mainly provide even fuel distribution to all pots at the best economy rate..

For electrical supply redundancy, I'd think a fairly small LiFePo4 battery could be plumbed in, utilising the more reliable charging functionality of the CAMit standard-type alternator that has much better protection from dangerous voltage spikes than the Jab style alternator. In fact, I don't think I'd be happy even running the EFI box from anything other than a well-regulated supply, for safety reasons, and certainly NOT any LiFePo4 type battery. Even quite a small (say around 1 kg, 8300 mh-hour HobbyKing battery) should, I'd think, give a decent amount of EFI-running capability - enough to get well along the way to a bug-out destination and set up a get-there height profile that assumes you may need to go back to carby-only power settings.

It would take some intelligent system design for both the fuel and electrical supply, but the beauty of the EFI supplementary is that once the EFI is programmed, it should be possible to apply the entire package to any Jab engine and the EFI will handle the different individual engine / operation characteristics.

Well, that's my theory... cue the dance of the effema angels-on-a-pinhead philosophers..

Incidentally - a basic MOTEC EFI controller with I think all the capability required is around $2200, injectors about $100 each, new intake runners shouldn't be more than about $100 each, a high-pressure fuel pump what - around $200? Add ilnes etc, total hardware, maybe around $3.5k.

Then, it would need testing, fiddling etc. - but if someone were to develop a complete, programmed package it'd be possible to amortise the cost over a number of installations, surely?

Trying to make myself heard above the static of a certain engineer who loves to twiddle with his femur - sorry, FMEA - can I just drag us back to the boring regime of practicality here?

This thread is about the use of CAMit engines - primarily in Jabirus. Short of major re-engineering, that per se imposes a whole set of parameters on what can in fact be done and multi-carby inlet tracts, major changes to the inlet arrangement, whippy-doo automated carby heat boxes etc. is at the very least pushing the envelope.

The major attraction of the CAMit engine is that it can be plugged in to the front of a Jabiru with essentially NO difficult changes and offers better reliability at a highly competitive cost. It's a bloody bolt-on better option.

There are, without doubt, a considerable number of changes that COULD be introduced to enhance the performance, reliability etc. of CAMit or indeed basic Jabiru engines. Killjoy that I am, I'm going to suggest certain limits in the interests of practicality.

Those limits include: NO changes to the engine mount, cowlings, and only minor tweaks to the W&B situation. NO increased PIC workload. Potential cost of changes to be amortised over one rebuild at 400 hours vs. one rebuild at 1000 hours. NO insurmountable problems with meeting regulatory requirements. NO nett loss of utility of the aircraft. Plus - preferably - the ability to remove whatever changes have been done and revert to standard if experience finds they don't work, or worse. Also, preferably, no (or very little) double-expenditure for reverting to standard (beyond the initial cost of the bits, at least)

Let us assume that the CAMit engine addresses the 'internal' problems: things like through-bolt issues, oil pressure and temperature control, crankcase movement, exhaust valve heat dissipation, rocker gear loading, rocker lubrication, shaft harmonic balancing. To me, that leaves really only airflow cooling and fuel mixture as the known problem areas. We KNOW that these areas can cause serious damage to any Jab engine, and in a very short time - if it were not a serious problem then it wouldn't be worth chasing solutions. We KNOW that a perfectly happily performing Jab. engine that is inadvertently operated too far beyond limits can go from fine at opening the throttle at the start of take-off to BANG by 1,000 feet as a result of detonation. You don't have to be an engine-molesting monster to have that happen: with a tankful of dud fuel, someone who has a perfectly reasonable climb-out regime instilled in her or his mind, that 'always' works fine, can be caught out.

Seriously: how many reports have we seen of people stating (and I am sure, absolutely genuinely) that they have had a failure of a Jab engine that was being operated 'absolutely normally', has not been previously abused etc., let go? I've seen plenty, and in not ONE case have I heard of anybody subsequently having the fuel in the tank analysed. Of course, fuel quality isn't the ONLY cause; if 'normal' operation has the cht's routinely near the top of the green, even (and if only one cht is installed, the likelihood is very high that some of the pots have been running in the red at times) - that engine is being degraded quickly.

The supplementary EFI idea will fit a standard installation, it's a matter of changing the intake runner tubes for ones with injector holders. Everything else can be located around the existing engine mount etc. and reversion to standard is simply putting the old runners back on. I suspect that smarter people than I can readily work out a ratio of 'basic fuel delivery' from the carby and 'fine tuning' fuel to be delivered via the EFI system so that even instantaneous EFI failure at a critical moment doesn't result in total loss of power.

That there are better solutions possible than the sort of hybrid I'm suggesting, is certain - but at what cost of far more major changes to the basic aircraft? That can be accomplished without major journeys into testing and approval? Nothing comes for nothing, but if we were to put our collective heads together and work through a smorgasbord of ideas to some depth for each, my personal feeling is that the 'suppplementary EFI' idea will remain as a potentially reasonably attractive and 'do-able' option.

These guys don't only work the RAA ads, they even work the Jab. site ads. and this site!. I put in an ad on the Jab. site for wings for our ST1, and got an offer of a pair, excellent condition, delivered from the UK for GBP$1,000. Yeah, as if. When I responded asking for details, (to keep things short here) - I was told they'd been removed from a slightly-crashed ST1, and had the serial number ST1 #0001. Just send the cash Western Union and they'd be on their way to me!

One minor problem I saw - the wings from ST1 0001 were sitting, along with the rest of ST1 0001, in my garage.... He'd gotten the serial number from my 'Wanted' note on this site! (because he'd quoted what I wrote, which actually didn't quote the serial number exactly correctly, as any Jab owner will recognise).

I played the guy along for a couple of weeks getting more info out of him, even sent him scurrying to firstly a Western Union office (with a false receipt number) and then an Instagram office. I had numerous bloody phone calls from him ( sub-continental accent, very English name..), then sent all the details I had to the UK On-Line Fraud people who didn't even respond to me. Then told him to sod off.

A week later, I got the SAME offer for sale (identical wording) from another name in the UK., which I ignored, and several more over the next couple of weeks.

Oh, agreed. HOWEVER - this thread is about CAMit engines (and by default, I suggest, getting the maximum utility from them). One of the highly-attractive things about the CAMit engines is the fact that they don't require changes to the basic installation and therefore the cost of them can be directly compared to the cost of a Jab replacement / rebuild engine - you don't have to go through the torture of re-engineering from the firewall forwards to plug one in. Additionally - there is a 100% 'back-up' available in terms of a standard Jab. engine. These are features not to be lightly ignored.

So the genesis of the hybrid discussion came from curiosity about how one could achieve further improvements to operational reliability etc. within fairly small parameters of further modification and in the broader context of applicability to ALL Jabiru-based engines. The obvious candidates, I suggest, are improvements in cooling arrangements and improvements in fuelling management - with the over-riding caveat being that it be reasonably 'do-able'. That, of course, means compromise - it's highly unlikely, I think, that one could make quantum leaps without significant changes to the underlying engineering.

Compromise inevitably introduces value judgement as to the priority for one factor over another vs. the benefit / cost of other factor/s. Compromise is, I think, de facto exclusive of the possibility of a 'silver bullet' emerging. Add in things like regulations and liability issues and it gets really damn complicated, but that doesn't necessarily mean we shouldn't have the fun of talking about it.

Well, hot damn, where is the smiley for 'Don't Poke the Engineers?' Don't give me 'prolix', sunshine, you're not an ex-PFC...

A couple of quick points. The flow-straightening improvement for Jab. engines is more broadly known than just the work done by Ian McPhee; at least one member of the Sonex Jab-user group ( Lyn Matheson, I think is his name) has been working on those for at least several years, and I THINK I saw a reference somewhere recently to Jab. USA having an OTS flow straightener available, though don't stake me with yer slide-rule if this isn't so. Without doubt, it's one step that every Jab. owner should consider (and preferably implement, with due attention to testing).

Adding complexity to any system is fundamentally undesirable, I yield the field there. However, in every situation one should look at the cost-benefit ratio before dismissing potential solutions to a problem. The point made that we are seeing more and more problems with cars recalled because of faults in the electronics is, I suggest, because the level of complexity they now have has gone over the top of the 'benefit' curve to the point where they try to be everything to everyone at the push of a button. When you have hulking great SUVs with 'Comfort - Normal - Sport - Track' settings that vary everything from the engine response through the gearbox change points, proportional diversion of power through the differentials to every damn wheel, plus steering response and suspension compliance adjustment, it's getting ridiculous - no, I correct myself - it's gotten ridiculous..

In this particular case, I believe we are faced with several major problems - and these are real problems, not the manufacturer's PR department dreams for product differentiation.

The first of these is dealing with varying fuel quality - and that is a problem that is, I very strongly suspect, going to only get worse for RAA-class aircraft operators. What we have here is a developing situation where the capability of auto EFI systems to deal with varying fuel quality has allowed the fuel suppliers to get away with sloppier standards and Australia is particularly bad for this - just about every high-performance vehicle sold in Australia has its engine de-rated because of our known poor-quality fuel. Even so, we get reports of auto-engines destroyed - recently, the NSW Police destroyed a high-performance Falcon engine with one fill of lower-grade fuel than recommended (cracked the block!). Some manufacturers go so far as to recommend only certain brands of PULP - the Golf GTI, for example, effectively mandates Shell, I think it is.

As far as I am aware, Jabiru has withdrawn the higher-comp. barrels it used to supply so they can accommodate PULP. One small step etc. - but ironically, Jabiru not so long ago indicated in their Jabachat section, that they were getting a statistically significant number of reports of problems with the aromatics in Shell V-Power PULP attacking the fuel tanks. So by trying to solve one problem, another one arose. What to do if you're in need of fuel in Didjabringabeeralong and the only servo around is a Shell station? Do you restrict your operation to airfields where 100LL is available - and can you even access airfields where 100LL is available?

Next problem: yes, mixture-adjustable carbies obviously exist, but they are only as effective in maintaining acceptable fuel mixture ratios as the competence of the operator to monitor and adjust mixture correctly. Of course, the time when doing that is most critical is initial climb-out - exactly the time when one ought, I think, to be (mostly) looking outside the damn cockpit,not to mention playing around with speed, revs, trim, flap settings, etc. For an experienced pilot well in tune with the aircraft, I imagine this is a deeply-ingrained dance done by second nature, but statistics suggest that the majority of RAA pilots don't really do enough hours to keep the fine edge sharp. Perhaps when my own experience is adequate for me to make that judgement I'll change my opinion - I'm sure others can provide better guidance.

Third problem: particularly with RAA-class aircraft, we are often juggling with trying to squeeze the best performance out of a pretty (weight) limited amount of fuel and as-safe-as-possible operation. Just chucking buckets of fuel at the engine to keep the temps down is not necessarily an optimal solution.

Is a hybrid system necessarily the bastard child of a 'last lady in the pub at closing time' encounter? Well, the Rotax has been mentioned. Now it is a hybrid system: you have air-cooling plus water cooling, which improves tolerance to differing fuel quality but introduces an additional failure potential: a broken hose, a failed water pump.. oh, and two carbies, doubling the potential carby failure situation. I'm not at all sure that a Rotax represents a free launch..

The EFI'd carby hybrid I'm postulating is possible to incorporate on a standard Jab. engine without changes to the existing installation. I think it's worth a bit more consideration than just being damned by a thousand FMEA cuts.

Well, they were a very large, uniformed body of terrorists operating under the guise of a national strategic objective, if not under the 'legitimacy' of a declaration of war. I doubt we would see such a force of RAA pilots assembled, at least without the sponsorship of Clive Palmer AND Gina Rinehart. Not even for Natfly.

Conclusion: If you are negligent, even if you have provided a warning, plaque, waiver etc. this case doesn’t help you.

Absolutely - but in every case you cite, the attackers were not terrorists, but legitimate governments engaging in war (or national commercial advantage, which is just one degree removed..). The combatants would NOT have been issued with an ASIC by the attackee government, at any price.

No, actually it damn well doesn't. Bloody engineers... can't hear the train for the whistle. You are talking failure rates, I am talking crashes. Do try to -ing LISTEN.

Yes, more systems delivering fuel increases the statistical probability of a component failure. What you numerically-retentive types fail to accept is the potential for outcome. An instantaneous engine failure during a high-risk period of flight - let's say, at 500 foot off the deck when maintenance of Vx is crucial to survival has an entirely different impact on the likely outcome than a prolonged engine shut-down event that starts when cruising at 8,000 AGL over open, flat country. Both will score 100% on the 'engine stopped because of component failure' table, which is where you are coming from. However, the result of an instantaneous failure that ends up with the aircraft in a crumpled ball of flame on the side of a steep hill vs. a gradual failure that results in an annoyed PIC landing deadstick at an unfamiliar airstrip and seeking the assistance of the local L2 to get the noise working again is a very different animal, from every POV other than the POF statistical one.

People - can we just pause here and inject a little reality?

CASA did not just suddenly decide that an ASIC card was a good idea. This was a Federal Government decision, from the top: a direct result of John Howard being in Washington when the 9/11 planes hit the WTC. That is not a politically-biased comment - it's bloody FACT - check when they became necessary for confirmation. The ASIC is just one manifestation of a 'security overlordship' mentality that is part of the baggage of Federal governments; it would take a PHD paper to explain it and you need to go back to at least Arthur Tange (aka Cur Arthur Tange) to even begin to comprehend where it was gestated in this country. You can discern the threads back to Machiavelli.

As much as I personally think CASA is fairly close to the Devil incarnate in terms of its black hand on aviation, you have the wrong target in relation to the ASIC. CASA is just the paper-shuffling authority designated to implement Federal Government policy here. In fact, CASA's legislative mandate if questioned with forensic exactitude would, I suspect, show it does not even HAVE the power to require ASIC. A Constitutional challenge would very probably result in overturning the CASA authority for the administration of ASIC.

Don't target CASA for the realignment of the ASIC card requirement to something approaching sensible - target the Federal Government. Target the Minister for Transport. Target the bloody Prime Minister, the Attorney-General.

The ASIC is complete bullshit in a society where anybody with the appropriate skills - let alone licence - can drive a B-double full of petrol into the middle of a CBD and explode it vs. a 600 kg MTOW full of petrol aircraft flying into the side of a building, FFS. With the greatest malice in the world, the use of an RAA-class aircraft just CANNOT inflict the sort of damage that other mediums that are completely unregulated can achieve. Aviation is being touted by a completely unscrupulous Government as a potential danger at a level that is patently ridiculous, simply because it was the medium for the to-date worst attack. And let's not forget: the ASIC card requirement would NOT have negated the 9/11 attack situation. The ASIC is simply a symbolic measure designed to alleviate the fears of a gullible public that aviation activities threaten their lives.

People: we as RAA-class aviators are being held out to dry by the whole ASIC thing. However, redress is not by attacking CASA but by exposing the venality and stupidity of the Government. Let's get the correct target and concentrate on it.

You keep talking about EFI failure that stops the EFI delivering fuel. What if the EFI fails such to deliver too much fuel? There are a few Continentals around, which suffer rich cut - i.e. they stop whilst at TO power, full rich - if the boost pump and engine pumps are fully functional (in event of an engine pump failure on takeoff, the pilot automatically turns the boost pump on... see, certification = safety...).Now I agree that the maximum EFI delivery can be limited - but if the failure mode of over-delivery is eliminated by introducing a failure mode of some auxiliary electromechanical device, the FMEA gets no smaller.

One simply works out every possible failure mode - however unlikely; and its effect(s) on the operation of the aeroplane. Summing the probabilities of each failure mode to cause, say, an AC23.1309 "serious" effect, shows the overall probability of occurrence of this class of event; which is then compared with the acceptable probability of failure.

 

Since probability of failure is related to time, one generally reduces the inspection or maintenance intervals until the target acceptable pof is reached. The job is not to say, "my injected car is better than my carby car was, therefore..." anything; the job is to say, "based upon this data, according to this table, the Soggysquish injection setup when tied up with string, gives half the PO (serious) F of the certified carby setup".

However, in terms of the 'overall' system delivering a manageable situation in case of failure of a critical component at a critical moment: assuming that the EFI system maximum fuel delivery capability is sized appropriately, which happens faster: damage through over-lean situation or loss of power through over-rich? We cannot ever assume that any system can be made foolproof, since by definition fools can exceed the imagination of those with the intelligence to be tasked to design the 'fool-proof' system.

I'm no expert on Human Factors, but I suspect that there is a vast gulf between having to react in around two seconds or less to a sudden overtemp situation heading towards detonation and terminal failure of the engine, and say ten seconds of increasingly rough running, scanning the egt's, realising that they are woefully low and deciding that there is too much fuel being delivered and hitting an EFI-OFF switch. The equation here is not JUST the POF figure, but the degree to which F is manageable.

Despite what the chattering media (and the fillums) suggests, there is an interval between engine failure and a crash. Gracious me, there is actually NOT an impenetrable nexus between 'noise-off ' and 'smash into the ground in a ball of fire'! I know I'm being radical here, but I dare to suggest that with a level of redundancy in fuel delivery systems - with the optimal mix of redundancy determined and applied - we could actually IMPROVE safety by adopting a hybrid system.

Anybody who grew up with carburettored cars knows that carbies CAN fail. I had a Renault R8 that regularly died when the spray-bar on the Solex became dislodged - to the point where I could re-engage it in the bloody dark, by feel, and I always carried the necessary screw-driver. We have redundant ignition systems, redundant fuel pump systems - but we fly without any redundancy for the carby! - and that is accepted, because nobody has come up with a system that can provide redundancy for the carby.

Electronic systems have a bloody fantastic reliability rate in real-life terms - and the added security of self-checking PLUS 'limp-home' failure mode. The use of basic POF statistics simply doesn't cover the full gamut of the potential of a hybrid system to reduce the risk of a component failure resulting in a crash.

Maybe 6 for the 3300, say 4 for the 2200? (let's be conservative here and treat our engines with lavish love..) Depending on the flight profile, that's getting up towards 80+ nm for a four-hour flight, which is starting to be a useful improvement in range, because if you think about it, for a full day's flying, you get about a 100-nm circle of options for your mid-point fuel stop at the very least!

I do believe that there's more to look at than just 'basic' numbers here, though. For careful owner/operators, things like economy and better protection against odd batches of fuel would be significant, but for operators who have their aircraft on the line, I suspect that just the improvement in engine management that would happen automatically instead of having to rely on the user consideration factor could be a real bonus. Let's face it - if you don't know about/ train the aircraft hirer on the finer points of engine management, having a system on board that limits the possible damage from ham-fisted operation just has to be a worthwhile investment in the potential cost of repairs and downtime.

And that's without the added potential cost of a mid-air cessation of noise due to really BAD engine management, in that flight or any before it..

Rich cut.

Can I just re-state the proposition: you have a complete, operational carby-fed fuel system that is set up to provide, let us say, 75% of the fuel required at 75% power. You have a supplementary EFI system that is capable of supplying all of the extra fuel for 100% power. The EFI system is sufficiently sophisticated that it can vary mixture to each pot as required to keep egt's within limits, stop detonation etc.

That gives you - I believe - optimal mixture delivered to each pot for all phases of flight. You therefore get the advantages of both best achievable economy and safe engine management, no matter what the quality of the fuel you happen to have filled your tank with, any peculiarities in cooling airflow / inlet tract variations / single plug failure etc. in any momentary change of circumstances.

Your back-up in case of EFI failure - particularly at a critical point in the flight - is use of the 'choke' function of the carby which is now set up to be capable of adding sufficient extra fuel when selected for 100% fuel at 75% power, or perhaps even at say 85% power. Hell, if you routinely fly out of a site that absolutely mandates max. ROC on climb-out, you may want to set it at 100% power. In this extreme case, you may even want to adopt an operating regime that incorporates not switching on the EFI until climb-out is completed so you remove the added worry of perhaps having to pull 'choke' (let's call it 'combat rich' for a giggle) at a critical part of the climb-out - because it's already on. Then, once in 'cruise climb' or above, you select EFI-ON and 'combat rich' off. In theory at least, if you DO have a '100% fuel delivery' setting on the 'combat rich' jet, then the EFI won't be delivering any additional fuel anyway, thus negating any effect from EFI malfunction until you close the 'combat rich' selector. The transition to EFI-efficient cruise in normal situations would be completely automatic on closing the 'combat rich' selector.

I don't see any of this as being more complicated than managing carby heat and boost pump operation. You use the EFI for start-up to provide starting choke fuel mixture condition - and if the damn EFI is O/S then the engine won't start, which should be enough to keep you out of trouble unless you're seriously inventive.

Would the additional EFI system be cost-effective to add? Probably depends on how you typically operate your aircraft, but I suggest there are some fairly decent arguments to say that for Jab-based engines, it would be very well worth consideration. Here's a few ideas I'd like to throw into the mix:

Jab. engines do not tolerate out-of-limits heat situations at all well, as we know. If you can eliminate all occurrences of an out-of-limit heat situation, typically (it appears) you can get double or more the time between overhauls, and just ONE overhaul is going to (in all likelihood) cost more than the complete EFI installation.

Fuel quality: the future for 100LL manufacture - at least on the East Coast - appears precarious, with both the Shell refinery at Geelong and the BP refinery in Qld. changing ownership. I think it is highly likely that it will only get more difficult to obtain 100LL elsewhere than at major airports where RAA aircraft can't go; and the usual pattern of RAA aircraft use is such that it is highly likely that on any decent trip you are going to have to use fuel from the local servo of unknown quality (age, composition etc.). You are very likely to end up with a hybrid mix of fuel at some point.

Economy (aka - range). Anecdotally at least, it seems that you can expect at least several litres/hour saving with an EFI system over a pure carby system, so for a say four-hour flight you gain an extra 8 litres of 'free' fuel - extending your effective useful range by around 50 nm. That's not much, really - but if most of your flying is around the Eastern area, from the coast across to the 'middle of the bush' area, it could be the difference of having several refuelling sites available, or not. You might not save much per litre on the purchase cost of the fuel itself, but if you can save a $50 call-out charge / expensive taxi-rides to and from the fuel station by having a wider selection of potential refuelling sites, it could quite quickly mount up to a decent amount even on just one several-days trip. Not worth it for just tootling around a well-supplied local site but worth consideration for those who use their aircraft for more serious touring.

I haven't looked closely at them, but they don't seem to be stirring up the PL community.Any impact would apply in NSW only and relate to the cases only, so that's a very narrow escape alley.

Add to that the plaintiff saying a ticket was bought, or the pilot offering the throwaway line "We only put that sign on to get registration etc) and the alley narrows.

 

Then there are any appeals which may occur and any High Court action on a future case if it is important enough.

 

Of course, the byproducts of the crash - the occupants of any other aircraft, and any people or property on the ground close the escape alley even more.

 

Also, I think in the Campbell vs Hay case much was made of the pilot warning that flying was hazardous, but I didn't hear whether the case was actually won on the fact that the Defendant had not been negligent which would make a lot more sense than what was in the media.

Actually, in my idea, the carby is still supplying partial fuel mix all the time so the entire carby fuel delivery system remains operative - just running at a lower fuel delivery quantity. You could probably do a double-check of both systems on run-up by starting her up (using both systems ON, to provide the choke), then do a second mag drop check with the EFI switched off - if it splutters and dies, the carby-fed circuit isn't working..

If the injectors can be sized so that they can provide full fuel mix in the case that the carby is iced/otherwise inoperative without being over-sized when it isn't, then you have added security (though I think it'd be wise to retain carby heat to ensure that great gobs of ice don't build up in the carby and then get sucked into the valves..)

All this seems too simple in concept to be reality. There has to be a huge Catch-22 somewhere lurking..

Good grief, man - next thing, you'll be proposing that one should keep the carby set-up but tune it so that it is delivering a consistently lean-of-optimal mixture (jet and needle combination..) and use the EFI as a 'mixture top-up' mechanism to deliver a tightly controlled and optimised mixture to each pot.

Then I suppose you'd argue that one might use the choke facility (re-tuned to provide a 'safely rich', not a 'starting rich' solution) as the fall-back 'get you out of trouble' device if the EFi goes to silicon heaven - since in normal operation the EFI would supply the ideal rich starting mixture, the 'normal' choke isn't required. So, you're flying along, the EFI dies, you pull 'combat rich' and start looking for a suitable bug-out site - and fly appropriately.

If all of that could be achieved - and the hardware to do it is a set of injector tubes on the intake runners plus the EFI controller and the high-pressure fuel delivery circuit - CASA might find it damn hard to argue. Putting CASA in a difficult position to enforce its prejudices is a very dangerous game - probably the best option is to make a break for the tree-line...

I would have no doubt that CAMit could make a simple mechanical FI pump - but that would be providing a solution to a problem that isn't looking for one.

We don't need a 'better carburettor', we need a fuel delivery system that is continuously and very rapidly adaptable to specific changes in the delivery of the fuel/air mixture to each pot. I accept that in theory, the ability to provide individual injectors at a late point in the intake tract to each cylinder does allow for a more effective intake tract arrangement than the squashed-up single-plenum-into intake-tubes we have at the moment - but that arrangement does allow for some fairly simple redundancy capability to be integrated into the overall system, whether this be by retaining a carby or having a back-up single-point injection device (e.g. a megasquirt-style independent arrangement) in the plenum intake.

What CASA is doing, is protecting its liability under S8.2 of the Civil Aviation Act 1988. Unlike the FAA (and all other National Airworthiness Authorities of which I am aware), CASA can be sued; S8.2 of the Act says so in words of one syllable. So CASA is seeking to reduce its vicarious liability for the design approvals made by Authorised Persons in the industry, by eliminating them. The first step was to close CAR 35 and replace it with CASR 21.M, which limits the scope of these people to minor modifications, and vastly increases the paperwork involved - and hence the cost. It also increased the liability exposure of the APs; so naturally the cost of an approval went up by almost an order of magnitude. It will get worse; within about three years, CASR 21.M individuals will have to become CASR 21.J Design Organisations (this is the EASA model).These changes are also a consequence of the policy of "following World's best practice" - which means, in effect, avoiding any necessity to think about what works best for Australia. The CAR 35 system was unique to Australia; but the "Cringe Australia" policy has prevailed yet again.

 

So, if you want to tinker with the thing, starting with an LSA aircraft is about the worst choice; and a certificated aircraft is getting to be the next worst choice - tho it was not always so. Starting with a certificated aircraft is by far the safest choice, however. If you start with a -19 aircraft, you are starting from something that has not been proven to comply with ANY safety standard whatsoever. Caveat Emptor.

While there appears to be an attraction for a relaxation of 'the rules' so we can just get on with flying around 'at our own risk', I am very much of the opinion that there is more to be feared than gained. If we are, as a group, effectively designated as 'outlaws' in a legalistic sense then I suggest that we may well find it difficult to argue for being included in airspace decisions, consideration of claims for reasonable access to landing sites, quite possibly we may find insurance either increasingly expensive or indeed impossible to obtain. I suspect it would also open up a broad avenue for people of a shonky nature to operate in our field of activity under the shield of responsibility being ultimately on the owner/operator/passenger.

19-reg and VH-exp provide a way for those who seek 'freedom' (well, a relative amount of 'freedom') from rules pertaining to their aircraft. I think that we all, (probably) recognise the desireability of having a 'class' of aircraft that can exists with those freedoms and complimentary restrictions on operational capability, but one size does not fit all. CASA appears to be, by protecting its liability, placing us all in a 'class' of their choosing, which is equally unsuitable.

The RAA submission to the 'Truss Review' was, I think, a significant opportunity lost to position 'Recreational Aviation' on a more realistic footing with decent consideration of the somewhat competing goals of 'freedom' and 'community acceptability'. Whether those competing goals can be reasonably reconciled, I am not sure, but I suspect that if we as a group do not start to think about this issue then we may well find ourselves backed into a corner by judicial rulings.

Look, if we were MEANT to use EFI, Kugelfischer wouldn't have made mechanical fuel injection for petrol engines!

Electronics are cheap for the capability - ridiculously cheap. You could carry a spare (programmed) motherboard and a couple of injectors and have a back-up dedicated LiFePo4 power supply installed - all for less than 2kgs. With reasonably sophisticated algorithms, an individual sensor failure can be accommodated. Hell, with the capabilities of a moderately sophisticated EFI, you could ingest a seagull in one cooling intake and probably limp to a safe landing without damaging the engine!

With a decently-designed electrical supply system (not something cobbled-up by a bush electrician), the only real serious failure mode that won't be normally detected on initial start-up would be lightning strike. RAA aircraft are not supposed to fly in areas likely to have lightning strike. I postulate that the incidence of lightning strike is statistically FAR less than the incidence of below-spec. fuel delivery - for which the EFI system can compensate.

The whole use of EFI is a matter of risk management assessment - and there has been way too little analysis of the chain of risk in a 'conventional' - i.e. carburettored - fuel delivery system vs. EFI. The potential additional benefits over and above the mechanical improvements CAMit have made to the basic Jabiru engine in terms of reducing the vulnerability of the engine to varying fuel quality and cooling installations is something that - in my opinion - every 19-reg (or VH-exp. certificate) Jab-engined aircraft owner might seriously want to consider.

Nope, not on board, and nobody injured other than a slight cut on somebody's head from the headset bracket (looks like). Actually was quite a gentle somersault - the prop was vertical and the blades worked like a progressive crumple zone, snapping off as it went over; the flange was bent out of serviceable but the shaft was fine. Fin hit the ground pretty hard and looks like one wing hit a fence post or sapling, but as Bob says above, the virtue of a solid, room-temp cure 'glass structure is it is extremely repairable, if you know the techniques and have the right equipment (including soda blasting and vacuum bagging gear). If it had been a c/f airframe, it'd have been a litre of unleaded and a Bic lighter job.

A finectomy is no major problem at all, though it now has a UL fin in place of the original which should give quite a bit more rudder authority (but requires more dihedral to compensate). The most difficult repair in some ways was caused by damage during recovery.

Certainly is! EFATO, overturn, fin smashed, one wing attachment ripped out, damage to both wings (replaced). Compounded by obvious extra damage through ham-fisted retrieval. Through-bolt failure...

However - and I say this in all sincerity - this was another aircraft that shows a history of engine problems that suggests a major amount of 'unsympathetic' operation (training fleet most of its 3700-hour life - and when we dismantled the engine, there was evidence that it should NOT have been rebuilt.) Altogether too much evidence of it having been poorly maintained - engine and airframe alike. Some minor repairs that were signed-off by an L2 that are a bloody disgrace. It says heaps for the basic durability of the airframe that it continued to do its duty.

Which is a completely reasonable position! (and I appreciate the hopeful note - a great many hours have already gone into our project, in airframe mods, repairs and general refurbishment as well as the engine rebuild and work still in progress on oil and airflow cooling improvements - the EO itself runs to 14 pages and it isn't complete yet - and that's without the test reports etc!).

The whole thing is, there's never been a sufficiently detailed compilation of the actual causes of failures to really get a full handle on why what happens, happens. Nobody would argue that Jab. engines aren't finicky, nor that there haven't been design problems - if that were not so, then what CAMit are doing would make no sense. However, the very lack of application of forensic-style examination of causes (and I am entirely comfortable with saying that Jabiru themselves have not assisted as well as they could in establishing the real causes, preferring to scuttle behind 'operation' too readily) has meant that many people have lumped the 'failures' into convenient large boxes, all tending to be labelled 'fundamental design flaws'.

Frankly, neither 'side' of that situation has been of very much use in furthering the useful development of the engines - and I think that any reasonable person would see that as a bloody shame for the owners and operators just as much as for the factory. Jab. engines have some very desirable features - light weight, simplicity and economy being the leading ones - and some far less than desirable ones. They are, without a shadow of doubt, the 'weak link' in an otherwise rather admirable aircraft in terms of initial purchase and operating cost, reliability, primary and secondary safety and mostly just a damn good combination of attributes.

I don't believe that CAMit would persevere with the Jab. engine as the basis for its improvements if it did not understand the problems and believe in the solutions it has developed. I think there are going to be some rather happy campers coming away from Natfly who have talked to Ian Bent and seen the work that has been done.

Well, I guess replacing six bolts every few hundred hours is cheaper than having to buy new Rotax crankcases. However, it shouldn't be happening, though I think it's a bit of a stretch to extrapolate from the earlier design problems to assume the latest iteration has the same failure rate. That said, we are going to the new CAMit alternator which assists in smoothing the crankshaft harmonics and I do not expect to have any problems with the flywheel bolts.