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Piper Navajo - at least 10 dead in engine failure accidents in the last 15 years, some other accidents without fatailities. Is that better or worse per hour than Jabiru? Considering that they are supposed to be maintened at a level several increments higher than an RAA aircraft. What percentage of Australian registered Piper Navajos have had off airport landings or crashes due to engine failure?

If the intention is to take a stick to Jabiru, it seems like a strange way of going about it. Why wouldn't you just e.g. suspend their authority to certify new engines until a fix is developed, and revoke any authorizations for Jabiru to fly over built up areas? The RAA rules were developed when 2 stroke engines were common, and on the assumption that engines were unreliable e.g. must be able to glide clear of built up areas. Does the Jabiru engine have worse reliability than 2 strokes? Is the accident rate high enough that those rules are not enough? I don't see it. It looks to me like the rule was designed to have maximum impact on RAA and related businesses, without the headlines that "Jabiru grounded" would generate. I genuinely fear for the future of all RAA based on this, not just Jabiru. Even if the proposed restrictions do not go ahead, the publication of the consultation draft is very damaging to Jabiru and RAA. Just the knowledge that the threat has been made must influence the value of Jabiru aircraft, and the business plans of Jabiru and businesses that depend on them. Once you pull a gun on someone, your relationship is irretrievably altered - even if you don't pull the trigger.

The instrument defines a Jabiru engine as "an engine that is wholly or partly manufactured by a person under licence from, or pursuant to a contract with, Jabiru." Are you sure that those engines are not even partly manufactured under license from Jabiru? Simply modifying an engine so that it is no longer considered a Jabiru engine for the purposes of certification doesn't seem to be enough...

That wasn't how I interpreted eligible. Correct? I'm not sure. What other requirements and standards should be used to determine whether they should be granted the endorsement? 61.495 specifically excludes people eligible under 61.500: 61.495 Requirements for grant of recreational pilot licence endorsements (1) This regulation applies to a person other than a person who is eligible to be granted a recreational pilot licence endorsement under regulation 61.500. So the requirements set out in 61.495 don't apply. Are there any other requirements? I looked for some other uses of the word eligible in these regulations to see if I can work out what it means... 61.280 The holder of a commercial pilot licence or an airline transport pilot licence granted by the Civil Aviation Authority of New Zealand is eligible for an equivalent Australian licence and equivalent ratings and other endorsements Seems to be a pretty close match in usage and intentions. Do they have to do a flight test to demonstrate that they meet the standards, or do they just have to apply? That is written in the regulations and it basically makes sense because normally the flight test counts as a flight review, so if you didn't do a GA flight test you don't have a GA flight review. And it is a logical place to have a proficiency check, and allows an instructor to verify that they really do meet the standards. This issue only really arises if you get the RPL, and then do a RAA nav endorsement - which bypasses the navigation component of the flight review. So you wouldn't issue a sticker for a tailwheel endorsement if requested by another instructor, without conducting a flight test yourself? I agree that CASA should be granting the endorsements - they seem to be the logical people to be issuing licenses and endorsements in recognition of existing qualifications, not individual schools/instructors...

I don't operate under an AOC. I can see how that would be required for a commercial operation, but what about private? If you do your AFR a month before it is due, and the instructor isn't happy with your practice forced landings, are you allowed to rent an aircraft and go and practice until 2 years from your previous review, or are you grounded?

That goes without saying, but the question is whether you can stop them from flying home in their 172 if you think their flying is not up to PPL standards?

I don't think that's a good idea. While RAA and GA are different (weight limits etc), there is a logical justification for the RAA medical requirements being different. I fear if the RAA/RPL qualifications are merged and it is 1500kg across the board the RPL medical standard will be applied and a large number of RAA pilots will be grounded.

According to 61.170, they "must grant a flight crew endorsement ... if ... the applicant meets the requirements mentioned in this Part for the grant of the endorsement." (my bold) The requirements in the Part appear to be met by 2 hours instrument time and a RAA navigation endorsement, so by my reading there is no "should" about it, the regulations say "must". Asking you to fly a nav is the same as passing your PPL flight test then being asked to do another nav to make sure before the license is issued. You have met the requirements, the license should be granted. Years ago I did my GA tailwheel endorsement. The instructor who did the tailwheel training didn't have authority to issue sticky labels. So I had to get a different school/instructor to issue the label on his say so. They didn't ask me to demonstrate tailwheel proficiency before they issued the label - they trusted the instructor who provided the training. Same deal here. The regulations say that CASA trust RAA to provide adequate training for a RPL navigation endorsement. So they need to either trust them, or change the regulations.

Yes, but 61.480 says that RAA navigation endorsement is recognised as meeting the required level of the proficiency and ticking the boxes. You may still need to demonstrate proficiency separately via a flight review, but 61.480 says that you have passed the flight test for issue of the license. As far as I know there isn't a way an instructor can actually ground you once you have a license, short of reporting you to CASA. If you fly in for a tailwheel lesson in your 172, the instructor can't stop you from flying home again. If you want to rent an aircraft from a school they can ask you to take a check ride, they can refuse to rent you an aircraft, but they can't take your license away. They can advise you that you shouldn't be flying, they can tell you your flying is rubbish, they can report you to CASA as needing remedial training but I don't think they can ground you themselves. I have a PPL so the RPL issue doesn't affect me, but it does annoy me when CASA and others ignore what the regulations say because they would prefer they were different. If RAA pilots need to demonstrate proficiency before they are issued the endorsement that's fine, write it in the regs. But if you write regs that say that you trust RAA, then follow through and trust RAA.

I don't see anywhere under 61.480 or 61.500 where you are able to reject someone based on competency. As I read it, if they have the RAA nav endorsement, and the 2 hours instrument time, they qualify for the endorsement. If they don't have the 2 hours IF you can do the instrument time with them, but when 1.9 clocks over to 2.0 instrument time *bing* they qualify for the endorsement regardless of standards. This does actually make sense - the "recognition of other qualifications" is basically saying "we trust the training and testing of this other organisation" and if you are allowed to fly a Jabiru to Broken Hill, you will be allowed to do the same in a 152. If you decide that they need to demonstrate again that they meet the standards (61.480 says they are taken to have passed the flight test) then you are no longer recognising the other qualifications. What do you do if they don't meet the standards? I suppose the same as you do when a PPL comes in for e.g. a tailwheel endorsement and you feel their overall flying is not up to scratch - whatever that is. As far as liability goes, I would have thought your liability increases the more training and assessment you do. If 61.500 gives you no discretion - and I don't see any there - the responsibility is on the organization that issued the qualifications being recognized.

Yes, a flight review is required before you can exercise the privileges . However, I don't think you can do a flight review for a license you don't hold, which implies that the license must first be granted, then you do the flight review.

I don't see where it says that, even if that is what some people would like. If you have to demonstrate the competency and knowledge in the MOS, in what way is it a "recognition of other qualifications"? What else would you have to do in addition to demonstrating "competency and knowledge required by the Manual of Standards" if you didn't have the other qualifications?

See: http://legacy.rotaxowner.com/si_tb_info/serviceb/sb-912-065ul.pdf Rotax seem to issue the service bulletin in a separate document for the UL engines.

That's OK. Since it's the difference in pressure that produces lift it just means the flow underneath needs to slow down more.

It may be a damn fool argment, but every attempt to explain seems to raise a few questions. In your article you say: Isn't this the equal transit time theory? But videos showing pulsed smoke e.g. in the other thread, clearly show that the flow doesn't get to the trailing edge at the same time. How does this work and why doesn't the air underneath "pile up" ahead of the wing? I don't know - but I guess some of it ends up flowing over the wing in the faster stream, as well as around the wing in the wider circulation patterns. In fact it seems like there must be less air flowing under the wing, to allow for the downward flow off the trailing edge.

Actually I take that back - it doesn't require it at all, since the venturi is only one surface. It just demonstrates that static pressure reduces as air speed increases - which is OK. It is the step comparing half a venturi to a wing that is incorrect - which is commonly taught.

There are certainly instructors who teach the equal transit time theory, and CASA appears to require it. From the part 61 MOS: "Apply Bernoulli’s theorem of constant energy flow to describe how an aerofoil produces lift, limited to the variation of kinetic energy (dynamic pressure) and potential energy (static pressure) as air flows through a venturi or over a aerofoil" Explaining how an aerofoil produces lisft using the variation of pressure as air flows through a venturi seems to require an incorrect application of Bernoulli, presumably equal transit time. In fact, a venturi doesn't explain lift at all, because the air comes out the other end travelling in the same direction at the same speed, so it cannot possibly produce lift.

Settle down, I agree with you. All I was trying to say is that I don't understand the point that was being made in the original reference to sprintcar wings.

Flat on the top is an approximation. So is flat on the bottom for a conventional airfoil. There is more curvature on the bottom of the SC airfoil. If you measure the distance along the surface from LE to TE it is further on the bottom - which is a problem for the equal transit time theory. But I thought we had agreed that the equal transit time theory doesn't hold water?

I said sprintcar wings have nothing to do with an airliner. Probably what I should have said is that sprint car wings are curved on the bottom for a totally different reason than the wings on an airliner.

I basically understand what you are saying about the SC wing. I found the stuff about avoiding accelerating air over the top near the speed of sound quite interesting. I just wasn't getting the point of comparing it to a sprint car wing.

I still don't understand your point here. He says that from what they are taught, people expect that a wing curved on the bottom and flat on the top would produce a down force not lift. And yet that is not the case for SC wings. I'm not sure whether you are agreeing or disagreeing?

If you understood Aerodynamics for Naval Aviators better you probably wouldn't be arguing with completeaerogeek. They did mean all the lift, not just the top part of the aerofoil. Bernoulli's equation explains the pressure above and below the wing (as long as the assumptions in the theory are valid) - it also tells us that as the flow slows down, the pressure increases. And lift is the difference in pressure between the top and bottom of the wing. It doesn't even matter if the pressure above increases, as long as the pressure below increases more. Sprint car wings are just a high camber wing at a high angle of attack, upside down so they produce downforce rather than lift. Totally different and unrelated to the wing on an airliner.

Fundamentally, I am agreeing with you. A practical understanding of what is happening is not difficult, and helped immensely by videos like the one at the start of the thread. Also videos of tuft testing wings as they stall - widely available now on Youtube - help immensely in visualizing flow and what happens when the wing stalls. However I wouldn't say Bernoulli, Newton etc. are practical aerodynamics - they are theory. And anytime you have to include assumptions you are acknowledging complexity, because the assumption basically says "this bit is too complex to include, but it doesn't make a significant difference in this situation so we can ignore it." It introduces complexity because you have to understand exactly when the assumption holds, and when it does make a difference and you can no longer ignore it e.g. assumptions that ignore compressibility. Newton and Bernoulli and all these theories of lift tell us nothing useful about the cause of a stall. Fluid dynamics can probably predict a stall based on viscosity and pressure gradient or something (I don't know) but we learn nothing about that as a pilot. What we need to know is that at some AOA the flow can no longer follow the shape of the wing, and there ia a large reduction in the amount of lift. This is based on AOA, which in turn is based on speed and load factor. It can also be influenced by contaminants on the surface, depending on the airfoil. This is what I meant when I said "why the wing stalls and what happens". This is practical aerodynamics, and I agree that it is not complex.

A lot of this thread is like one person arguing that red traffic lights mean stop, others arguing that green means go. Newton, pressure, bernoulli etc all exist and all play a part. What is wrong is many of the oversimplified explanations generated by people who didn't properly understand it in the first place. People tend to seize the first one they think they understand and promote that as the right answer. Newton: is a law of the universe. It is not optional. Lift force is generated by accelerating a mass of air downwards. There is nothing else it can come from. Whatever other explanation is used, Newton is involved. Pressure: lift comes from a difference in pressure between the top and bottom surfaces of the wing. There is nothing else acting on the wing that can cause lift. It doesn't really matter whether the pressure below increases or the pressure above decreases, it is the difference that matters. The difference in pressure caused by the wing causes air above and below to accelerate downwards, which is required for the lift force. Likewise the acceleration produces the pressure difference. This sounds paradoxical, but the law is "every action has an equal and opposite reaction" - since they are equal and opposite, you can call either the action, and the other the reaction. Bernoulli: The air over the top of the wing is travelling faster and has lower pressure than the air below, so this is consistent with Bernoulli. However Bernoulli is based on conservation of energy. I suspect energy is transferred from the higher pressure areas to the lower pressure areas in the act of accelerating the air, which would tend to invalidate the assumptions. Bernoulli applies as far as the bernoulli conditions are satisfied, but we don't have equal transit time, and the air doesn't always (usually doesn't?) split exactly at the leading edge. The classic explanation of the bernoulli effect is a venturi, but this is not the only situation where it applies. It's just an example that has been used and abused. Air deflected by the lower surface: Air pressure is a result of the number and energy of molecules bouncing off the surface. A higher pressure has more molecules or more energetic molecules bouncing off the surface. So this explanation is really just a different way of saying that the bottom surface has a higher pressure than the top surface. Some other observations: Lift from a flat plate: Have a look at the streamlines around a flat plate producing lift. The pressure field starts to deflect the air ahead of the plate, causing the airflow above and below to be similar to a basic airfoil. Symmetrical airfoil: similar to flat plate i.e. the airflow above and below is NOT symmetrical Airfoil shape: The purpose is to precisely control the flow of air around the wing to reduce drag, to prevent it from detaching (stalling) over a wider range of angles of attack, and to control where along the chord the acceleration occurs, which influences the pressure distribution (centre of pressure) and how it changes at different angles of attack. Supersonic? Way beyond my knowledge, but I think one of the keys is to shape the top surface to avoid the airflow detaching, without the influence of the changing pressure ahead of the wing modifying the airflow. You really need to know very little of this to fly an aircraft. You need to know the effect of speed on lift and drag, why the wing stalls and what happens, the effect of surface contamination etc. Newton, Bernoulli etc are really irrelevant to the task of flying an aircraft. They are taught badly, without real understanding, and I think most pilots are confused. * Aerodynamics is complex. I have been interested and learning about it as a hobby for 30+ years. Year 12 physics and chemistry is very helpful but the more I learn, the more I discover that I don't know. These explanations probably also have errors and inaccuracies. I have concluded I have no hope of understanding it properly, unless one day I go back to uni and study it at a tertiary level. Luckily, that level of knowledge isn't required to fly an aircraft.