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HomeTurbineAircraftHelicopterTurbine Helicopters › XLV main blades
02-08-2008 09:16 PM  10 years agoPost 41
G-SWSMrrApprentice - Midlands, UK - My Posts: All  Forum  Topic

Hi All.

So, I was wondering,

Would the BMFA, or whoever governs this hobby whoever that may be, let us use these blades legally from an insurance point of view if we were able to keep certificates that state that they have been "safety checked / XRayed" for fatigue etc.

We send our models in for servicing / bearing changes etc, so why not just send in the blades to the manufacturer annually, or even bi-annually dependant on the number oh hours they have flown.

This seems like a perfectly legitimate option to me.

As paying members of the BMFA, we renew our membership annually, so why not send in a photocopy of the required inspection report / certificate at the same time, or bi-annually.

Does this sound reasonable to all of you.

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02-08-2008 10:13 PM  10 years agoPost 42
chopper jockey

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uk

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It does not sound practical to me. The BMFA insurance will not be invalidated anyway. Indeed the only way the insurance can pay out is if the insured was negligent. It will not pay out on any genuine accident unless it can be proved to be the insured's fault.

I have total confidence in metal blades. I use them very often in a slightly different form, on both of my fullsize helicopter tail rotors. They are under emense stress and rotate at about 3,000 rpm.
They do not have to be X-ray'd and are not subject to NDT. Just a visual check before each flight and an engineer looks at them twice a year.
Much ado about nothing IMO.

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02-09-2008 01:32 AM  10 years agoPost 43
FCM

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Surrey, England

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They do not have to be X-ray'd and are not subject to NDT. Just a visual check before each flight and an engineer looks at them twice a year.
Same as metal propellers and even fan blades on a large gas turbine.

It does not make any sense to me why the BMFA should be concerned about metal fatigue and not concerned about delamination and hidden internal damge that does occur with composite main blades!

As an example, I have just retired a set of SAB810 carbon main blades as the trailing edge of one blade has become 'soft' when you squeeze it. Where is the BMFA guidance for inspecting composite main blades?

The 'issue' with aluminium alloy fatiguing is not straight forward anyway. It depends of the alloy used, the design and the method of construction. And why limit it to main blades? What about alloy blade grips aren't they subject to the all of the loads and more that a main blade is?

This ruling has been thought up by a layman I'm affraid, who has 'heard' something about certain alloys fatiguing.

Going back to the M-Blades, the fact that they are acid etched means that you will be getting a near perfectly manufactured blade free of machining marks and other stress raisers. This manufacturer obvously does know all about aluminium alloy and how to form it.

Paul.

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02-09-2008 06:09 AM  10 years agoPost 44
dazzaster

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right next door to hell

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blades on a full size are made to a extreme high standard compared to thoes you would get from a manufactorer who makes them for models!
as for the insurence if there was an incident/acident where someone got hurt through the use of metal blades there would be an investigation and court prodceding to prove you where leglegent.
the courts/investigating persons not knowing anything about model helicopter would there for seek profesional advice from the governing body in this case the bmfa no matter if the person was a bmfa member or not or flying at a club or in a public place. and despite the letter G-SWSM has received ill garentee in a legal situation the bmfa would turn round in a court and say something like "it is clearly writen in our hand book that no model should be run or flown with metal blades"
and down comes the hammer with 10 years for causeing death by negligence ,the insurence might pay the victims comepensation and your court fees but youll still be inside trying hard not to drop the soap
Darren

A.K.A 509

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02-09-2008 08:01 AM  10 years agoPost 45
FCM

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Surrey, England

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No model helicopter blades are manufactured to any airworthiness standard. It doesn't matter if they are made from aluminium alloy, graphite, glass fibre or laminated wood, you are trusting a manufacturer of model components that they have got there sums right and do have adequate manufacturing quality control in place. Which would you rather buy main blades from: A mainland Chinese company making graphite blades or a German company making etched aluminium alloy blades that are in compliance with German aeromodelling regulations which from what I can gather, are amongst the most stringent in the world. I know what I would rather trust.

Paul.

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02-09-2008 08:27 AM  10 years agoPost 46
dazzaster

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right next door to hell

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paul dont disagree with what you are saying about quality. chopper jockey said the tail blades of his helicopter get a visuel check by an engineer my point being you cant compare this to model metal blades as they are made diffrently, full size heli blades have a lot more test done at the manufactoring point and then get a part number and a seriel number and probably a certificate of being fit for there use.
i think if we where permitted to use metal blades it would be a good thing. but without any legal control over servicing ect it wont be a good thing.
the general public don see helis the way we do they see a heli with woden or carbon fibre blades then it looks to them like a toy. as soon as you mention metal they dont see it as a toy and concidering the local councils could be seen as joe public (ie:they dont know about the hobby ) then it could cause a few problems.
untill the bmfa are willing to come up with some procedure for useing metal blades and back it fully and not back down will i be prepared to even consider useing them.

A.K.A 509

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02-09-2008 08:29 AM  10 years agoPost 47
ba board

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England

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It does not make any sense to me why the BMFA should be concerned about metal fatigue and not concerned about delamination and hidden internal damge that does occur with composite main blades!
You obviously haven't had many dealings with the BMFA then. This is just another example of how screwy their policies are!!!

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02-09-2008 10:41 AM  10 years agoPost 48
FCM

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Surrey, England

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I agree that it is probably down to perception that aluminium blades are nasty spiteful things that can lop your head off whereas weighted graphite blades are really just plastic and "how is that gonna hurt anybody anyway"

But I don't agree with your comparison with full size heli's using alloy tail rotor blades as full size helis flying composite blades have far more complex manufacturering and maintenance inspection procedures due to the problems associated with delamination, water ingress and hidden sub surface damage none of which are a problem with the old and tried alloy blades of yesterday. I ask again - where are the BMFA composite blade inspection procedures? If you need them for alloy then you need them for every other blade material.

I have had dealings with the BMFA before. Their technical committee used to be made up of plank flyers who 'new' what was best for everybody Sound's as though it still is

Paul.

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02-09-2008 02:58 PM  10 years agoPost 49
chopper jockey

rrApprentice

uk

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and down comes the hammer with 10 years for causeing death by negligence ,the insurence might pay the victims comepensation and your court fees but youll still be inside trying hard not to drop the soap
daz, come now, you will not go to prison unless you break the law. Using metal blades is neither negligent or illegal.

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02-09-2008 07:28 PM  10 years agoPost 50
dazzaster

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right next door to hell

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i didnt say it was ilegal ,i just simply said it would not help you out in a legal case if the bmfa, who would be called upon by a court for a profesional aproach to an acident/incident involving a flying model turned round and said to the court something like "we clearly state to all our members in our hand book that metal blades should not be used apart from that mr xxxx model aircraft was prepared with acordance the handbook.

A.K.A 509

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