Another hub bar found cracked

[Adrian S]

Guys,

I thought I would post this as Tim has gone public on the US forum.

We had a report that ASRA is presently investigating of another cracked hub bar. This didnt lead to a death thankfully but could have. What really upsets me about this one is that the mustering pilot concerned didnt comply with the ASRA AD- no testing after 500hrs and continued to fly with it even after the mandatory replacement age at 800hrs.

The Hub bar had just under 1000hrs of mustering use.

Guys ASRA put a lot of time and effort based on real evidence to come up with the AD that is designed to save lives.

Another death in the mustering/training proffessions through failing to comply with the sound advice found in ASRA directives will certainly lead to loss of our privlages.

If you hear of anyone giving contrary advice to the ASRA AD's please let me let me know as we need to track down
these idiots and silence them before more people are killed.

Spread the word!

Adrian.

Adrian Stoffels
Tech Manager
ASRA :chainsaw:

[russ]

Adrian...........thanks for the alert.

Interesting that "president" of "asra", notified yank forum, some days ago and would not tell his own members here in AUSTRALIA via this site, that there was a serious incident, right here within our own member group......[and he does "lurk" here, he has confirmed that to me on a previous occassion]

Yea.............it speaks volumes of his regard for members here. [ Mr president.............sorry, you gota go, you have had too many strikes, you are now "struck" out.] :anger:

Adrian..........what brand blade please............is there a pattern showing here with a "manufacturer" ?????????

I've been flying these things for near on 30 yrs, and i'm no sunday morning driver.............never, ever, did we crack bars.........and blades were only replaced after we dinged them, we were getting a zillion hrs on them, without a single crack.

There's more to this "new" problem, than we realise, mandatory replacement of bars at XXXhrs is to me an excellent decision, but it's not "the fix" it's just averting a problem...........we have to spend "asra" money, and get "expert" advice...............WHY are they cracking. If it means we as members may have to top up the kitty........so be it.
One day, it's going to kill some bugger, and it might be me.........or you

Again..........thanks for your alert...............

[Adrian S]

Guys,

I am reluctant to post to many details as I have yet to recieve the hub bar for testing and analysis.
What I can tell you is they were an early set of Kinetics.
I reiterate that I have examples of most of the popular blades that are manufactured here and in the US that are used by musterers and trainers - they all crack after hitting certain fatigue cycles. Mustering and hard training especialy lots of circuits give the most fatigue cycles per hour. We know why they are cracking.

The AD came about by averaging the failure times and then taking away a little for other variables.
We can design another head and hubbar approach that will have twice the fatigue life but will cost 5 times as much to build, then we will probably exceed the blade life! We can design you a blade set with more blade life then we need to upgrade the airframe introduce hydraulic assist for you controls etc It is never ending.
There is no aircraft parts that dont have a fatigue life because we need to match the variables of strength, weight and cost. Remember the our Gyro environment is unigue everything is subjected to multiple fatigue cycles and variable loads not just in the air but also whilst we trailer them around.

Our present gyro approach is a compromise between ability to home manufacture, weight and cost and thankfully we generaly due it well.

Regards,

Adrian

Everything in aviation is a comprimise!

[Birdy2]

We know why they are cracking.
Unfortunately Adrian, only sum of us KNOW, and i bet alota 'instructers' dont know why. Yes, hours will eventualy break them, but its not going to break them under 1000, or even 3000 hours, its the handeling that over stresses them. Wether its on the ground or in the air.
Alota people think that blades cant be unduely stressed once they are at flyn speed, and this is a dangerous assumption.
Like you said, you can beef up the bars, but then the next weekest link is go'n to let go.

Wots needed is the hour limits we already have, and sum education on handeling on AND OFF the ground.
[ and not just for the mustering crowd, i'v seen sum weekenders punishn their blades just as bad, if not worse, but only outa ignorance.]

[rotor]

Adrian,

Thanks for the heads up mate. We appreciate your early advise and the work that you and others do making things safer for everyone.

Much appreciated

rotor

[Aussie_Paul]

Guys,

I thought I would post this as Tim has gone public on the US forum.

We had a report that ASRA is presently investigating of another cracked hub bar. This didnt lead to a death thankfully but could have. What really upsets me about this one is that the mustering pilot concerned didnt comply with the ASRA AD- no testing after 500hrs and continued to fly with it even after the mandatory replacement age at 800hrs.

The Hub bar had just under 1000hrs of mustering use.

Guys ASRA put a lot of time and effort based on real evidence to come up with the AD that is designed to save lives.

Another death in the mustering/training proffessions through failing to comply with the sound advice found in ASRA directives will certainly lead to loss of our privlages.

If you hear of anyone giving contrary advice to the ASRA AD's please let me let me know as we need to track down
these idiots and silence them before more people are killed.

Spread the word!

Adrian.

Adrian Stoffels
Tech Manager
ASRA :chainsaw:

Hi Adrian, I believe that there is an ASRA instructor with over 1000 hours on his trainer blades who will not replace the hub bar. A student rang me re training as he did not feel comfortable with the other instructors stance on a safety issue that has no second chances.

It is bad enough with a single seater not to abide by the ADs, BUT a trainer!!!

Aussie Paul. :redface:

[Adrian S]

Birdy,

Your comments are spot on, the AD is only one part of the solution the next part needs to be education about rotor management both whilst they are on the ground stationary, being spun up, in transition and at full flying speeds.

The proposed new mustering/low flying endorsement will go someway to speading the word and re education of instructors and weekend flyers alike will also help.

Smooth, balanced flying leads to less fatigue.
Abrupt, unbalanced flying leads to higher stress on both machine and pilot.

Russ,

Your comments concerning the apparent reduction in hours before the hub bars crack is also valid. The main contributors to this in the past ten years has been the increase in AUW of machines,the increase in reliable HP of our engine , prerotators and the move towards high energy blades.

Unacceptable blade shake is a high stressor, I see too many guys accept real blade shake as the norm. Take the time to tune & balance them and remember that a lot of problems here also come from poorly set up rotor heads.

Paul,

Hopefully ASRA gets to know the name of the instructor concerned and we can re-educate him.
The other outcomes are not so good for ASRA members - best case the word spreads around amongst the students and he go's out of business and we have one less active instructor or in the worst case he kills himself and the student and we all suffer.

Guys,

One last bit of advice - when ASRA developed the AD that lifed the hub bar we also trialed a number of NDT approaches - the one approved and published was found to be the most reliable. The use of Dye Penetrant testing has been found to be a poor indicator of the EARLY stages of crack propergation in hub bars therefore ASRA will not support this method for testing hub bars.

Rotor,

I would appreciate if you could you raise the profile of the AD and testing method o your site if possible.

I think this is enough for this post.

Thanks for your contributions and help to spread the word. :yes:



Adrian.

[russ]

Adrian.....dave........you are spot on with blade management, at ALL times.

Adrian.....yes, more powerfull engines, more weight, etc etc etc all contribute to more stresses to our blades, and machines......BUT..........

Why then, is this bar cracking problem confined to "Ozy" machines. We have yank guys with exactly the same weights, horses, etc etc, and to the best of my knowledge, they are having no problems what so ever with bar crackings.

I did hear a year ago, that a couple of ozy blade makers were getting "Chinese" extruded alloys, has this been investigated. :confused:
If that is correct, then we do need to further investigate the legitimacy of the alloy..[ 6061T6 ] or whatever it is "supposed" to be.
I am employed in the building game, and anything on site that originates from china just doesn't last the distance.......quite frankly ......it's garbage.........cheap garbage

[Adrian S]

Russ,

Regarding the authenticity of the 6061T6, whenever I send a cracked hubbar away for testing the alloy grade is also tested. All of the Oz bars have been found to exceed the american standards.

Regarding the american experience I have yet to find proof that they fly the number of hours that we do on one set of blades and their general operations appear different in training and mustering. In particular with training, they appear to spend more time teaching fixed-wing type landings where as we focus on full autorotations.

As far as mustering goes, they dont appear to use gyros for moving cattle like we do in Oz. Most of their agricultural operations appear to be equivelent to our fence and bore inspections.

I'm more than happy to be corrected by people who has any better evidence in regards to the american scene.

Regards,

Adrian

[rotor]

Rotor,
I would appreciate if you could you raise the profile of the AD and testing method o your site if possible.
I think this is enough for this post.
Thanks for your contributions and help to spread the word. :yes:
Adrian.


Adrian,

I have added an "AD" Forum. Specifically to point out to members here of any updates to or new AD's announced on the ASRA site. Please feel free to make postings in that area.

rotor