Dafydd Llewellyn

No, I made a statement that I prefer to either fly myself, or drive. Obviously, if I have to travel overseas, I'll fly. Fortunately, I've reached the stage in life where I do not have to be in a hurry to go places. The statistics show that flying commercial is remarkably safe - at present. I just don't feel comfortable with the overall situation as I see it evolving, since the competition was deregulated. If you consider the aviation industry to be a machine, of which CASA and its bretheren, together with the issuing of airline licences by Government, are the regulators, there is a parallel between this and an engine-driven machine regulated by a mechanical governor (Watt governor). The most important adjustment on such a machine is the tension of the governor spring; too loose, and the machine will overspeed and destroy itself; too tight, and it will stall and refuse to run at all. Deregulation is akin to removing the governor spring altogether; and the levels of competition we are currently seeing are akin to an overspeed condition that will prove destructive. There's a second analogy, which is what happens if the governor is sluggish or "sticky" in its action; then the system "hunts" or oscillates between boom and bust. If the phase lag is small, the oscillation will be small. If it's too far behind the action, the oscillation builds up so the thing destroys itself. Imagine what would happen if the cruise control in your car was ten seconds behind the action. Anybody who has studied control-loop theory should understand this. In any "free-market regulation" scenario, there will be unscrupulous operators who cut costs by cutting safety standards. The others must follow suit to remain competetive. Prices go down; for a while, the consumers are very happy. Sound familiar? Then the accidents start, or airlines start going bankrupt, people become disenchanted, and the market collapses. The unscrupulous ones - at least, those of them who haven't yet suffered a catastrophe, walk away with a fortune; the scrupulous ones who maintained their standards will go bankrupt. So the whole scene collapses. We lose the skill base necessary to make it all happen What I see right now, is about half way or a bit more, along this pattern. The problem with "free market regulation" is that its phase lag is too great; it tends to de-stabilise the industry. That's what I am seeing right now, with the whole global airline industry. We have gone away from the model of close control of airline licences, because it was manifestly unfair and being abused for nationalistic or other more unsavoury reasons, but in doing so, we have abandoned a form of regulation that acted before the event - and was therefore stabilising in its effect, without replacing it with anything that has a similar stabilising effect. I think we are going to discover that what control-loop theory tells us about a machine, also applies to the airline industry, and it will be a ghastly lesson. So I don't want to be involved in it, thanks. Go pick a fight with somebody else.

If a group of you get together and give the engineer a bunch of serial numbers, he may be able to give a single approval for those serial numbers. This was certainly possible under CAR 35; I understand the scope for this may be less under CASR 21.M. I do know it is not permissible to give an "open" approval under CASR 21.M. (Progress, it's called)

Well, that's between you (and quite a few other owners) and the RAA. No point in asking me, or crying on my shoulder; I was so disgusted by what I learned as an expert witness for Carol Smith, that I walked away from RAA - and I won't be coming back. I know people are trying to bail the boat out before it sinks, and I wish them well - but there are some people who should be shot for what was allowed to happen. I've given Trevor Bange what assistance I can offer. But RAA people have been living in cloud-cuckoo land for decades; it was inevitable that reality would someday intrude. You can't go back there. Go read my thread "caveat emptor". This forum is serving to put some daylight onto the scene, and to correct some very wrong-headed thinking, so I've been prepared to put time into it, despite not being a member. However, people ultimately have to help themselves. You can't rely on an amateur association to spoon-feed you; they are trying to teach - but only you can do the learning. One may well wonder just what was going on in the past - because it was surely not in the members' best interests. It needs vigilance on the part of the members to keep it on the rails - and that means you need to stop pretending that the regulations don't apply to you, but learn what they really say. Reading the regulations may put you to sleep - but it won't send you blind, any more that the RAA Mag. will.

No, it's fixed-pitch. it folds instead of being feathered, not as well as.

Because they look "wrong", I think. They're a bit heavier than an equivalent 2-blade, also. However, if you need to get rid of the propeller drag, as in a motor-glider, the alternative is a featherable Hoffman - and that costs about $ 15K AND you have to ship it back the Germany for overhaul every two years or so, AND it's not that light. I was after a vastly less costly solution.

No, of course it isn't. But it's not the fault of the engineer who will have to comply with his procedures manual in order to do what should have been done long ago. The aircraft IS flying illegally, and that should never have happened; RAA was negligent. Surely you can take it from there?

You're arguing with the regulations, then? Sorry, can't help you there.

Suits me - that's one less on the road.

Or maybe we need to get off the never-never and negative gearing bit, and generally abandon the borrowed-money merry-go-round. My wife and I purchased a default-of-rates 5 acre block in the western outskirts of Sydney, and looked at a project home after we were first married - and decided to build our own. It meant living in a Nissen Hut that we purchased from the Cabramatta migrant settlement for $ 200, for about five years. So we never got into the great debt cycle. We buy second-hand cars and overhaul them ourselves. We operate hand-to-mouth, pretty much, and avoid going into debt. Our life-style isn't flashy; but it suits us; it allowed us to get ahead, instead of paying interest to a lending institution. When I wanted a little sailing dingy, whilst we lived in Sydney, I built it. As a result, we now live on a 40 acre block; took 40 years to do it. When the weather gets cold, I chop wood; we have no shortage of it. When we moved to QLD, we purchased a second-hand QLD high-set house - about 1930 vintage - and had it moved 25 miles onto our block - total cost $28,000 in 1978. We've done a lot of work on it since - all ourselves. We don't give a damn what the neighbours think; and we chose a location where the local council doesn't make it difficult for owner-builders. We mow the lawns to keep the fire risk down, not for any other reason (apart from the airstrip). I would not go back to a suburban quarter-acre at gunpoint. To do those things more generally in the populace, local govt. restrictions on owner-builders need to be overhauled. Kids need to be taught how to do their own car maintenance, how to lay bricks, etc. Everybody did those things back in the '50's but most people nowadays prefer to earn money and pay somebody else to do it. If you're one of those, loss of earnings will hit you hard. I spent several weeks in Kuala Lumpur in the '90s, sorting out an engineering problem. Every house had a cottage industry in the backyard. Australian local government needs its collective heads banged together until it allows this in Oz. What Zoos sees coming is very much a consequence of the loss of self-sufficiency throughout our urban society. We have become inter-dependent, not self sufficient. SE Asia will swarm past us unless we wake up.

Yes, Barrie Bishton DID have one. After owning it for about ten years, he built a replacement set of wings for it, with a different airfoil, because it was prone to drop a wing, or just drop out of the sky, when he tried to short-field land it (necessary for his strip near Gunning), and he got tired of this quirk.

Why not? When you ask a CASR 21M Authorised person to approve a modification, you are asking him to take on legal liability for the design of the modification. Your tax accountant does not do that - he gets you to sign the return; he explicitly hands the liability back to you. Why do you expect a professional engineer to take on the liability for what is in reality a pretty shonky modification with little or no documentation, for peanuts? Grow up; you sound like a petulant six-year old - "Gimme - I want".

What kind of knots?

We DO have an experimental "category"; I say again, see http://www.casa.gov.au/wcmswr/_assets/main/rules/1998casr/021/021c10.pdf. It's actually a bit more liberal than the American one. But it's not an alternative to getting proper airworthiness approval for a modification. The mods you see on American GA built aircraft are almost all done via a Supplemental Type Certificate; there are thousands of them listed on the FAA website. Go look at CASR 1998 Part 21 subpart E. You're perfectly free to use that mechanism for any Australian-registered certificated aircraft; people do, but in the past that sort of thing was mostly done under CAR 35. The -503 Lightwing isn't certificated, so it can't have a supplement to the Type Certificate it doesn't have - but it CAN be modified under CASR Part 21M. But the process is not cheap, unless you can do most of the technical work for it yourself. All you need to do is to put together a set of drawings and work instructions, plus a justification report (which could almost be a one-liner) and submit them to either CASA or a CASR 21M Authorised Person (there's a list of them on the CASA website). Don't know how to do that? Then it will cost something to have the 21M AP prepare it for you. It will likely cost about the same as having an accountant prepare your tax return. Why wasn't that done way back when the 503 was replaced by a 532, and again when the 532 became a 582? Ask RAAus. They are the irresponsible party, plus the owners at the time. You have a legitimate basis for sueing RAAus for what you paid for the aircraft, I suspect - unless caveat emptor over-rules it. The sad fact is that RAA was presenting a facade of controlling its area in the Australian industry, whilst not actually doing so; and you are one of many victims of that. Be angry - be very angry, but be angry at the right party.

Yes, you are correct - that the change is minimal and therefore should be able to be approved at the stroke of a pen. But it's still a modification.

Dead right. Ignorance of the law is no excuse. See http://www.casa.gov.au/wcmswr/_assets/main/rules/1998casr/021/021c10.pdf

That either means, a lot of people are doing their jobs properly, despite the lousy management - or it indicates that there is a LOT of redundancy built into modern aircraft - or a bit of both; and the 747 was a quantum jump in that, tho the 727 was better than most people realise. Qantas has, observably, a very good set of pilots; right up there with Sully Sullenberg, in my books. But the overall level of competition in the airline industry can only put pressure on safety standards - and candidly, I do not have any confidence in "professional managers" who have not grown up in the full "safety culture", but are more commercially orientated. They are necessary, I suppose, given the level of competition, but this does not fill me with confidence; the second most nervous airline passengers are pilots; but engineers come first in that race. I used to be in charge of an old F-27 that CSIRO used as a flying laboratory for atmospheric research and remote sensing. It was maintained by East-West airlines, who at that time ran eleven of the things, and knew them backwards. It went into the field for three months at a time (whereas one in airline use got a check 1 every night and a check 3 about once a fortnight); and it was utterly reliable. I know in detail how that was achieved; it takes real expertise plus intimate knowledge of each individual aircraft, and you cannot purchase that by tender; you have to build it over time, and it has incalculable value. Qantas maintenance used to be second to none. What it is now, I don't know. But I have reservations about their management's understanding of that value. The RR Dart engines in the F27 were not as fuel-efficient as modern engines - but they had decent thermal margins; they'd start safely down to 24 volts on the aircraft's batteries - so you didn't need a battery cart, which meant it could operate for extended periods away from a major base. The push for better fuel economy has pushed turbine inlet temperatures up to the point where the engines are operating on a knife edge; a turbine reduced to metal spray by a hot start of the F 50 engines is an awesom sight - and so is the cost of it. The push for reduced structure weight means the airframes are made of unobtanium, and are working at high stress levels. Fly-by-wire is necessary so the things can fly at CG limits that are uncomfortably far aft - as a pilot friend of mine said, "Fly-by-wire is OK so long as the wire is 7 x 19". It's called "progress" but in my lexicon, it's "shaving the margins to the bone". Now excuse me, please - it's time for an oil change in my Subie.

The Boomerang was intended to be a Tomahawk replacement with a better fatigue life, mainly aimed at the CPL trainer niche. The Tomahawk had been "lightened" to the point of causing maintenance issues; that was done in order to use the Lycoming 0-235 engine. The Boomer is more solidly built, but accordingly it really needed an 0-320; a low-compression 0-320 with a wood propeller on it would very likely be a very suitable package for the Boomer, except that a CS propeller is necessary for training to CPL level. It was also intended to be suitable for spin training, but that turned out to not be the case - which severely reduced its market potential. A great pity; it had vastly superior survivability than any recreational aircraft; it met FAR 23.562 (dynamic seat testing - the equivalent of a motor vehicle barrier crash test; no recreational aircraft gets anywhere near that). Lycoming 0-320s are just about the most durable piston engine currently being made; that's a critical cost issue for a training organisation. The low-compression versions will likely tolerate the reduced fuel grades that we'll be stuck with in the near future. A certificated CS propeller for a Lycoming weighs around 63 Lbs; pray tell me what Tecnam - or any other LSA - could carry that? There are a plethora of LSA aircraft aimed at ab-initio training, so that part of the market is saturated. Most of them are really a bit on the fragile side, and I don't think any of them are spinnable. However their fuel burn is significantly less than that of any aircraft that is sufficiently solid to meet FAR 23.562. So we trade safety for cost; the bottom line always wins. If Dean Wilson made any mistake, it was conducting a market survey that asked what aero clubs wanted in a trainer. Wrong question - the answer would inevitably be "a better Tomahawk". The right question would, I suspect, have been: What things do aero clubs NOT want in a trainer. That might have led to the design of a more marketable product. Not necessarily a better product. Dinosaur? No, not really. But a very different concept to the "Renold's Wrap" specials that are around as a consequence of the LSA rules.

Yairrsss - I'm an aeronautical engineer, supposedly with some understanding of the aviation industry. Which airline do I prefer when I travel interstate? I fly myself, or drive. Marginal profitability and union action and offshore maintenance make my oldish Subaru look quite attractive, actually.

Essentially, yes - but the load transfer to the rear spar means the margin for gusts is diminishing faster than normal with increasing speed - and all the numbers are small, to start with

I think Oscar is confusing the Gazelle situation with that of the CA 21, which was certificated to CAO 101.55 / BCAR S preliminary issue. The design standard (certification basis) for the Gazelle can be found by looking up its Type Certificate Data Sheet on the CASA website. The basis was JAR-VLA with some variations. I do not have JAR-VLA to hand; however from its successor, CS-VLA, gust loads and manoeuvre loads are generally considered separately; that is to say, the aeroplane is assumed to be in equilibrium at 1G in level flight when it experiences the gust. I do not consider the Gazelle to be inherently dangerous when flown within its flight manual limits; however there is a load transfer from the front wing spar to the rear wing spar due to the very high wing airfoil camber, which has the effect that the whole of the wing load is carried by the rear spar at some speed between 70 and 80 kts CAS - closer to 70 than 80, I suspect. At higher speeds, the front spar carries a download, and thus the rear spar load is further increased. For this reason, the speed limits for the type really do mean what they say.

I think we had the best of it in the '60s. I consider myself lucky to have experienced that . . . Now, please wipe up the spilled beer & let's get on with what's next.

And that's with an aft CG limit at 38% MAC

That's a common misunderstanding. The Seeker is most unusual; its wing has a three-stage stall; the first stage stalls only the part of the wing between the leading-edge fences (i.e. the bit directly ahead of the tailplane). That has two effects: Firstly, the wing downwash acting on the tailplane is reduced - which limits the elevator power to pull it any deeper into the stall. Secondly, the wing fences shed powerful vortices at high alpha, which do two things - firstly, they prevent the stalled area from migrating further outboard; and secondly, they provide greatly increased directional stability at high angles of attack, because when the aircraft yaws, the sidewash from the lower part of the vortices acts on the vertical tail to push it back to the centre. If you apply full crossed control at around 1.4 times the stall speed, you will see about two ball widths of skid. If you then slow down whilst holding full crossed control, the skid will reduce to about half a ball width when the stick is on the back stop. That's not enough to make the stall patch extend outward, so it simply keeps on flying. It's not "mushing" in the normal sense*; I've done many flight demos in VH-SUA and one of them is to heave it into a full power steep turn with full aileron, full rudder and full back stick, starting at 65 knots - which is just 9 knots above the zero flap stall speed. Anything else would do a flick roll; the Seeker just turns & flies away - with a slight aerodynamic buffet from the stalled centre section. I did a complete set of spin tests (68 cases) on the higher-powered version (VH-SZF) with the aft CG limit at 30% MAC instead of 28% MAC as for -SUA; it does not spin; it will do a half-stalled incipient, falling into a spiral after half a turn. Keith Engelsman (ex CASA chief test pilot) verified my results. The airflow kit on the Seeker was the subject of intensive development; it uses vortex control to limit the lateral spread of stall. Such a system behaves altogether differently to a conventional aircraft. Forget your traditional experience; it does not apply to the Seeker. It's the only aircraft I know of in which you can apply full crossed controls and then bring the stick right back to the stop, without a violent wing drop - it just keeps flying. Turning stalls, power on or off, flaps up or down, it makes no difference. It was designed for powerline patrol, and it is extremely well suited to that job; there will be no stall/spin accidents in it unless people operate it outside its certificated CG limits. *Mushing refers to an aircraft that has such restricted elevator authority - usually due to a restricted aft CG limit and/or limited elevator travel, so you cannot use the full lifting capability of the wing. The Seeker does not do that; it lets you go to the fine edge of the peak wing lift - but no further, at any CG within the certificated range. And it does so by its fundamental aerodynamic design, not by a fly-by-wire system.

The 2Q head substitutes for both the pitot and the static sources, and it does so with very little tubing, especially if one uses a differential pressure transducer instead of a mechanical ASI. Attached is what it looks like, and the calibration curve for the one Jabiru use. A trailing static is not as suitable for stall speed testing, because if the aircraft is descending, it suffers from "lag balance" - the change in static pressure due to changing altitude creates an error, which can be quite large. This is due to the time it takes to fill the tube and the instrument case, which can be considerable for a trailing-cone static. Note: Systems such as the Dynon use a differential pressure transducer - but for certification testing, it needs to be calibrated immediately before and immediately after each test flight. If I'm using the 2-Q head with an ASI instrument, I usually cross-calibrate it against a trailing-cone static and pivoting-vane pitot, in level flight, just as a double-check. Jabiru_probe_calibration_2004.doc Jabiru_probe_calibration_2004.doc Jabiru_probe_calibration_2004.doc

Rudder lock is somewhat different to aileron snatch; it's a gradual reversal of the rudder hinge moment with increasing yaw, so when you set up a full-rudder yaw, and take your feet off the pedals, the rudder doesn't come back - you have to push it back. When you see an aeroplane with a dorsal fin ahead of the vertical tail, there's a fair chance it either suffered from rudder lock or the designer anticipated that it would. It's merely annoying in a glider, but extremely dangerous in a larger, faster aircraft. It tended to be common in the older German gliders which had a very small fixed fin and an enormous rudder, and no aerodynamic balance on the rudder. The worst Aircraft I found for it was the Ka2. Was your ASI calibrated? They are allowed up to 4 knots error. Stall speed testing for certification is quite a complicated business; if you want to study it, look up FAA AC 23.8a - which was the issue applicable to the J160. Attached is an excerpt from AC23.8b which was changed slightly; the applicable case is the middle one, and under issue (a), the stall speed was the lowest speed reached; under (b) it's the speed at which the stick hits the stop. The procedure is to do a large number of stall events, with the speed versus time being recorded so a curve similar to this can be drawn for each event. The mean rate of deceleration is the slope of the line between 1.1 Vs and the point at which the stick hits the stop. So you get a large number of results of stall speed versus deceleration rate. It is necessary to have samples at deceleration rates above and below one knot per second (all speeds in CAS). You draw a line of best fit through all the points, and the speed at which that line crosses one knot per second is the stall speed. It's actually one of the more difficult tests to perform in certification flight testing, because you have to fly extremely precisely. I tend to agree with your appraisal of the J 160.