Does anyone have more information on this NSW South Coast accident?

[Viper]

On the bottom of the pile on photo 18 it looks like the rudder to me. It looks like where the skins are riveted to the tapered tube. I'm constructing one of these so the investigation will be of great interest. Indeed I won't fly it until there is some real information available on this incident.

Yes Graham you are right having built one there is no other part that could look like that definitely the rudder

 

 

[motzartmerv]

Ive had word. Told to look at this. https://www.raa.asn.au/documents/airworthiness/Bowden%20Cable%20bulkhead%20nuts%20bulletin%2021072014.pdf

 

 

[Dafydd Llewellyn]

Yep thats fine. We all buy factory built. So what about people building their own but follow the instructions and don't change the plans to suit what they think is better?

If you're building from plans or a kit, AND the original aircraft from which the kit was derived, had a Type Certificate, then at least there's a background that the original design was thoroughly vetted by an appropriate third party, to verify that it complied with the relevant design standard. The design standards for recreational aircraft are not completely beyond criticism, but they are a big improvement on nothing. Bear in mind that aircraft design standards are always MINIMUM standards; they don't guarantee excellence, but they are intended to provide a tolerably safe product provided you use it within its limits, and they ensure those limits are specified.

However, a kit under the "major content" rules can be supplied by anybody; and it does not have to have been built and tested. There's no formal control of it whatsoever. Not of its design, nor of the materials supplied in the kit. You're right out on your own. So if you tackle one of these, you really need to have a lot of aviation knowledge, and every bit of help you can get. It can be done but the potential risk is high, unless you really know what you are doing.

 

In practice, the range can lie anywhere between these extremes.

 

An LSA kit is a half-way house; the original aircraft was self-certified by its manufacturer, and before he can do that, he has to either hold a Production Certificate (which means he has previously manufactured a type certificated aircraft, and has the necessary production quality control system in place) - OR he has to employ or otherwise use recognised aviation professionals with the appropriate qualifications. However, that is enforced after the event by the normal criminal processes that apply to fraud, so it can be abused (for a while).

 

I covered all this under the thread "Caveat Emptor".

 

 

[David Isaac]

Ive had word. Told to look at this. https://www.raa.asn.au/documents/airworthiness/Bowden Cable bulkhead nuts bulletin 21072014.pdf

Well that could do it Motz, that flying stabilator, let it loose and all hell can brake loose. What a bloody tragedy.

 

 

[Dafydd Llewellyn]

Hmmm. I once had to land a Jabiru with a disconnected elevator, because a cable outer anchor let go. In the Jab, you can land it using the elevator trim. It landed without a scratch. I think there's more than one message, there. FAR 23 requires that the aircraft can be landed with no elevator input - which is not quite the same as a disconnect, but getting close. That's the sort of thing I mean about the importance of understanding the design standards.

 

 

[Guest Maj Millard]

There appears to be a large fuselage side sheet that has all the rivets sheared rather then the sheet torn. Anyone know what brand / type of rivets used or recommended by Morgan?

You cannot design any aircraft to withstand crash forces like that....doesn't matter what sort of rivets you use.

 

 

[Teckair]

You cannot design any aircraft to withstand crash forces like that....doesn't matter what sort of rivets you use.

Yep quite true but that was not the question.

 

 

[kgwilson]

Ive had word. Told to look at this. https://www.raa.asn.au/documents/airworthiness/Bowden Cable bulkhead nuts bulletin 21072014.pdf

The cables supplied come with internal tooth washers which should prevent the nuts from loosening if they are done up tight. That is no guarantee though & I will definitely be wiring all of mine as per the bulletin plus some locktite.

 

 

[deadstick]

Another often overlooked mode of failure with the bowden teleflex style of cables are at the ball end, it is advisable to place a washer larger than the spherical bearing on the outside to prevent the cable from sliding over the bolt head if the bearing fails.

 

 

[biggles]

Things have changed recently; check out the latest developments; They will be investigating more RAA

What's changed recently , can you elaborate ?

 

Bob

 

 

[turboplanner]

Yes Bob, here is the RAA submission and the government response, and also prior to this there had been a move towards ATSB investigating EVERY crash (but that would take a bit more finding)

 

http://www.infrastructure.gov.au/aviation/asrr/submissions/files/127_ra_aus_30_jan_2014.pdf

 

http://www.infrastructure.gov.au/aviation/asrr/files/ASRR_Executive_Summary.pdf

 

 

[Oscar]

Well I'd imagine if you hit the water at a high speed, the water entering the fuselage from the front would literally blow the metal off all the rivets on the fuselage because of the huge concussion pressures. From what I saw of the photographs and what was reported; what you see on the photographs would appear understandable.

By blowing up the image of the detached fuselage sheet, it is apparent that the sheet did indeed 'blow-off' past the rivet heads - most of the holes are head-sized and severely dimpled inwards. It certainly looks as if no fault can be suggested for either materials nor construction technique, though obviously that is something that only the investigators would be in a position to determine.

 

This accident has, I think, been received with appropriate horror by everybody - the horror of catastrophic failure of a critical control system in flight, for what now looks as if it may have been caused by something as simple as a single nut becoming unwound and allowing a chain of utterly tragic events to happen. It would be a decent legacy for the two, by all reports, fine and careful aviators if something could be achieved that improves the safety for the rest of us. I believe that RAA is seeking to achieve such an outcome, though that is not going to be an easy path.

 

It seems to me that there is an inevitable tension between the freedom to accept the risk of one's own actions ( including all aspects of owner-building ) inherent in the nature of 19-reg. aircraft regulations and the role of regulators to mandate standards - these two elements pull mostly in opposite directions. It will be impossible to ever achieve a balance that satisfies everybody, but perhaps the risk assessment path offers the best chance: providing guidance to builders, owners and maintainers while not precluding someone from taking a different approach, with (hopefully) knowledge of the severity of the risk being accepted.

 

Just possibly, if the RAA community can be brought together by this accident to at least appreciate that the intention of any moves on this sort are based upon good intentions rather than the imposition of rules/guidelines for their own sake ( aka, by some, as interfering with their freedoms ), improvements can be achieved that will be 'for the common good'.

 

 

[Guest Andys@coffs]

........It seems to me that there is an inevitable tension between the freedom to accept the risk of one's own actions ( including all aspects of owner-building ) inherent in the nature of 19-reg. aircraft regulations and the role of regulators to mandate standards - these two elements pull mostly in opposite directions........

Is that really true? to me it will only be so if the intent of the actions is not parallel. I cant see anyone wanting to build a 19 registered aircraft that includes flaws where these are known and the quasi regulator just wants you if possible to avoid learning about them from first principles? That being so I think they pull mostly in the same direction......can you give me examples where they pull in opposite?

 

Andy

 

 

[Dafydd Llewellyn]

May I suggest that a way to approach this, for a scratch, plans, or "major content" kit, is for the builder of such an aircraft to acquire a copy of FAA AC 43.13-1 BEFORE HE STARTS, and also he should download a relevant design standard - they are all fairly similar - such as FAR Part 23, and read the relevant section of it as he builds each part, especially the sections on "Design and Construction" and "Engines". He doesn't need to be able to use the formulae on the structures part of it; just read the parts that are in plain english - which is most of it, actually. The devil is almost always in the detail. These references will go a long way to showing what details are important.

 

It would be good if the "risk analysis" mechanism can be set up so the kit supplier does this work, but in the meantime, anybody can do the above.

 

 

[Dafydd Llewellyn]

Andy, there's a quite strong "We don' need no steenking engineers!" sentiment out there. In the aviation mainstream, professional engineers go over the design against the design standard, line by line, and write reports to show the thing complies. CASA reads the reports, and there is often a ding-dong argument - but the end result can only be that CASA is truly satisfied that the aircraft complies with the design standard. That process takes several man-years and costs a lot of money.

 

The philosophy behind DIY experimental aircraft (however described) is diametrically opposite to that; it allows people to slap anything together and fly it - the only constraint being where and under what conditions they may do so. So the whole thing is opposite.

 

Judging by the responses I keep seeing on this website, almost nobody in rec. aviation has ever even glanced at one of the design standards. They all state what they imagine the requirement should be, without ever actually looking it up.

 

What I am advocating is using the established standard as guidance material for a risk analysis. The sort of question/answer that could be developed might include such matters of fact as "Does the elevator trim system drive the elevators independently of the main elevator control system (yes/no)" - etcetera.

 

 

[Dafydd Llewellyn]

By blowing up the image of the detached fuselage sheet, it is apparent that the sheet did indeed 'blow-off' past the rivet heads - most of the holes are head-sized and severely dimpled inwards. It certainly looks as if no fault can be suggested for either materials nor construction technique, though obviously that is something that only the investigators would be in a position to determine.This accident has, I think, been received with appropriate horror by everybody - the horror of catastrophic failure of a critical control system in flight, for what now looks as if it may have been caused by something as simple as a single nut becoming unwound and allowing a chain of utterly tragic events to happen. It would be a decent legacy for the two, by all reports, fine and careful aviators if something could be achieved that improves the safety for the rest of us. I believe that RAA is seeking to achieve such an outcome, though that is not going to be an easy path.

 

It seems to me that there is an inevitable tension between the freedom to accept the risk of one's own actions ( including all aspects of owner-building ) inherent in the nature of 19-reg. aircraft regulations and the role of regulators to mandate standards - these two elements pull mostly in opposite directions. It will be impossible to ever achieve a balance that satisfies everybody, but perhaps the risk assessment path offers the best chance: providing guidance to builders, owners and maintainers while not precluding someone from taking a different approach, with (hopefully) knowledge of the severity of the risk being accepted.

 

Just possibly, if the RAA community can be brought together by this accident to at least appreciate that the intention of any moves on this sort are based upon good intentions rather than the imposition of rules/guidelines for their own sake ( aka, by some, as interfering with their freedoms ), improvements can be achieved that will be 'for the common good'.

In point of fact, liability issues under the Trade Practices Act and Negligence in Tort both act to make it virtually impossible to impose rules or guidelines on experimental aircraft. As soon as any authority imposes ANY rule, Pandora's box opens and the lawyers step in. This was hammered out flat in the process of drafting CASR Part 21; as Middo will remember, you cannot have "a little bit of airworthiness" in any formal sense - either it is airworthy (i.e. it complies with the relevant standard fully), or it ain't. An experimental certificate is in reality a certificate of non-airworthiness - which is a legal concept - tho it does not mean the thing is not fit to fly - which is a physical state of the aircraft. However, a risk analysis approach functions to assist people to understand the nature of the risk they are accepting, and it's about the only way I can see to do that without opening the box.

 

 

[turboplanner]

Usually, if there's a safe industry benchmark, or "best practice", you have difficulties if you don't meet this.

 

 

[M61A1]

Andy, there's a quite strong "We don' need no steenking engineers!" sentiment out there. In the aviation mainstream, professional engineers go over the design against the design standard, line by line, and write reports to show the thing complies. CASA reads the reports, and there is often a ding-dong argument - but the end result can only be that CASA is truly satisfied that the aircraft complies with the design standard. That process takes several man-years and costs a lot of money.The philosophy behind DIY experimental aircraft (however described) is diametrically opposite to that; it allows people to slap anything together and fly it - the only constraint being where and under what conditions they may do so. So the whole thing is opposite.

 

Judging by the responses I keep seeing on this website, almost nobody in rec. aviation has ever even glanced at one of the design standards. They all state what they imagine the requirement should be, without ever actually looking it up.

 

What I am advocating is using the established standard as guidance material for a risk analysis. The sort of question/answer that could be developed might include such matters of fact as "Does the elevator trim system drive the elevators independently of the main elevator control system (yes/no)" - etcetera.

I am probably one of those that you refer to, however, I have made a lot of effort to educate myself as to how I might build a safe aircraft. I am not one to throw a few tubes and some bolts together and hope for the best, but there may have been some who would do that, and I respect their right to do that, as long as they are comfortable with the risk (regardless of whether or not they fully comprehend it), and as long as the risk to others is acceptable, and I don't mean grieving widows and family, solely harm to those in no way involved.

I would like to believe that those who take homebuilding (and their life) seriously, will assess the risk honestly, seek guidance where necessary, and physically test structures to make sure they are adequate for the task. Those who don't, may be lucky, or they may leave the gene pool.

 

The harsh reality is that when you get into the seat of someone else's homebuilt, you really should make sure you understand what you are getting yourself in for.

 

 

[Dafydd Llewellyn]

I am probably one of those that you refer to, however, I have made a lot of effort to educate myself as to how I might build a safe aircraft. I am not one to throw a few tubes and some bolts together and hope for the best, but there may have been some who would do that, and I respect their right to do that, as long as they are comfortable with the risk (regardless of whether or not they fully comprehend it), and as long as the risk to others is acceptable, and I don't mean grieving widows and family, solely harm to those in no way involved.I would like to believe that those who take homebuilding (and their life) seriously, will assess the risk honestly, seek guidance where necessary, and physically test structures to make sure they are adequate for the task. Those who don't, may be lucky, or they may leave the gene pool.

The harsh reality is that when you get into the seat of someone else's homebuilt, you really should make sure you understand what you are getting yourself in for.

Yes, that's the reality of it. I don't have an issue with people doing that; however I think the pathway to improved understanding can be made easier.

 

 

[nomadpete]

This latest direction of debate has been very illuminating for me. Thank you all for bringing such an important facet of our recreational aviating into the light of day.

 

I believe that although it is a definite drift off topic (and probably not relevent to the tragic accident which started the thread), we should bring the issue of standards, and the comprehension of same, to the forefront of discussions about Recreational Aviation (and its future) because it is all about the trade off which allowed us to enter affordable aviating. Also it is a critical aspect of risk management. Fortunately for us, so far there has been little evidence of structural issues causing any negative trend in our accident statistics.

 

Peter

 

 

[Dafydd Llewellyn]

I agree it's something that everybody in recreational aviation needs to understand. However it's a common mistake that aircraft design standards are mainly about structures; that's only one facet of it - and I suspect the aspect that causes the least accidents. I did say that people tend to state what they think the design standard requires, instead of reading it to find out what it actually calls for; that's a typical example.

 

The problem I see with most of the designs of recreational aircraft, is the fundamental philosophy; this is easiest to illustrate by the fact that the structures are almost always "single load path" designs - and so they cannot withstand a single failure anywhere. This is equally true of the control systems, the undercarriages, etcetera. The service bulletin on bulkhead nuts on push-pull cable systems illustrates this.

 

Light aircraft design standards require redundancy (i.e. the ability to withstand a single failure) only in regard to having dual ignition on the engine, and a back-up electric fuel pump in the fuel system, and (in the case of FAR 23) the ability to land the aircraft using the elevator trim system in lieu of the primary elevator control. Lately, one finds some mention of the ability to make gentle turns using only the rudder.

 

This practice arose, in the case of structures, because it was very complex to analyse a redundant structure, before computers came into general use; but nowadays, with Finite Element Analysis, it's fairly straightforward to do so. A redundant structure may weigh only a few percent more than a single load-path one, but the extremely tight weight limits for recreational aircraft largely preclude that extra weight. Airliners invariably have redundant control systems - one of the advantages of conventional cable systems is that a broken cable is not prone to jamming in the structure, as a pushrod is. So you find duplicated control runs to all the flight controls - the upper fuselage of a Fokker Friendship looks like the inside of a piano, with all the cables. That extent is not necessary in a recreational aircraft - but we need, I believe, to start thinking about failure modes for structures and control systems, etc, and learn how to do "smart" design to cope with them or eliminate them.

 

 

[poteroo]

It occurs to me that instructors are, perhaps, taking more than acceptable risk by agreeing to instruct or flight check in experimental category aircraft - be they GA or RAA. A subject which I have recommended to RAAus Ops that they include on the agenda for the November CFI meeting in Dubbo.

 

 

[facthunter]

Design could be improved in a lot of aircraft. IF a particular aircraft has weaknesses it should be known and inspections developed and practiced for that model. EG Skyfox rudder, aileron controls . I have always felt the need for duplication of pitch control capability as it is the ONE control you can't compensate for , unless you run back and forward along the fuselage. Lose it and you generally die.

 

Some aircraft have aerodynamic inadequacies that go from undesirable to dangerous.

 

A good plane becomes a crook one if it is not inspected and serviced, properly. If you do a FIRM arrival, do the right thing and inspect it thoroughly. Not just the obvious, wheels and struts.... Seat supports and engine, battery mounts etc as well

 

 

[Dafydd Llewellyn]

It occurs to me that instructors are, perhaps, taking more than acceptable risk by agreeing to instruct or flight check in experimental category aircraft - be they GA or RAA. A subject which I have recommended to RAAus Ops that they include on the agenda for the November CFI meeting in Dubbo.

People need to (preferably) do their flight checks on the aircraft they normally fly. It's up to the instructor. You could approach the issue of giving the instructor a basis on which to make his decision, by setting a minimum score in the risk analysis.

 

 

[facthunter]

The Instructor has right of refusal, surely. It's not a matter of being "brave" either. What then is the difference between the plane you don't like or a single seater? The fix is the same, fly in something else. If the aircraft is way out the instructor won't be familiar with it either. Nev