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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › How Long Do Blades Last and When do you Replace Them?
06-10-2015 01:00 PM  6 years ago
Andy from Sandy

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UK

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As part of your pre-flight check try twisting the blades and flexing them. If you hear any sound from them its probably signals the end for them.

How long they last for most people is until the next unscheduled arrival with terrafirma.
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06-10-2015 02:47 PM  6 years ago
Heli_Splatter

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USA

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Sorry, but even steel has limits...

Steel springs never break??? not here to argue, but if the max design loading is not approached, things will last quite a long time. Small loads with high frequency cycles can demo a material just as easily as large loads.

In helicopter blades, I would think that this is a very high frequency loading and unloading, even in straight and level flight.

My point is that, these will not last forever and the pilot needs to be examining them pre-flight. Some people will fly to failure, I hope that I am smarter than that and will replace obvious fatigue worn items. Even though it ain't broke, you may need to fix these.

I am certainly not going to tell anyone when... It would be nice to have some actual failure data on which to base the decision. I would like something like; after 500 hrs of flight on certain size bird the mains need to be replaced, but it is so variable.
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06-10-2015 06:07 PM  6 years ago
Aaron29

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USA

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If someone doesn't crash for 500 hours, and can prove it, I'll give them a set of blades. LOL.

That would be at least 3000 flights. At the rate I see the average person fly, this would take decades. I fly A LOT, almost every day lately, and it has taken two years to reach 600 flights on the Logo.
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06-10-2015 06:10 PM  6 years ago
Aaron29

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USA

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Check them for cracks and delaminating, but short of any visual evidence, I see no reason to ever retire a set of blades.

Wood, notwithstanding. I would personally replace woodies on a schedule. Not sure if there's any science to that. It's just that wood seems to dry out. Then again, there's furniture hundreds of years old if finished correctly.
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06-10-2015 06:52 PM  6 years ago
Steff Giguere

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St-Eustache, Quebec, Canada

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I'll show you a set of Rail 556 with 604 flights on them....maybe by IRCHA they will be at 650 flight on them. Blades might ware out but I agree do a preflight before every flying session and you will know when they need to be changed. I've never yet had to change out a pair of blades before I crashed them.Team Synergy, Rail blades, Team Scorpion, V-Team
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06-13-2015 07:55 PM  6 years ago
HeliRyan

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Colusa ca

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one would probably think until you crash or notice stress cracks in the blades .. For me the blades are always first to go.. Preventive Maintance can save ya $$ if you don't have deep pockets, for a complete rekit. Simple preflight checks can save ya, but parts fail so you know whateva.. LolI don't crash, I land at full speed!
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06-15-2015 01:22 PM  6 years ago
jharkin

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Holliston, MA - USA

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Sorry, but even steel has limits...

Steel springs never break??? not here to argue, but if the max design loading is not approached, things will last quite a long time. Small loads with high frequency cycles can demo a material just as easily as large loads.
Read my post carefully. Again, unlike aluminum, Steel has a fatigue limit, a part of the S-N curve that flattens out - if you keep all forces under that limit then the number of cycle are essentially infinite for practical purposes. This is a well known engineering principle we all learn in the first year of mechanical engineering school.

Just because you might see a steel spring break doesn't disprove fatigue limits. It just shows that the spring was subjected to a force beyond the limit stress.

This is what I wrote:

" You can bend it an infinite number of times but as long as each bend is less than the limit force it will never crack and break."

https://en.wikipedia.org/wiki/Fatigue_limit
-Jeremy
Whiplash-G
Helix 700G
T-Rex 450 fbl conversion
alot of planks
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06-15-2015 01:46 PM  6 years ago
Heli_Splatter

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USA

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Static loading. Lets talk dynamic
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06-15-2015 02:24 PM  6 years ago
MattJen

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UK / GRAVESEND KENT

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I know in some Ali blades we toyed with idea of filling them with dye so when they fatigued and cracked you'd see the dye in the hair line cracks..
Here in the UK after certain amount of hours we have to send them away to be checked.. but it does rely on pilots keeping strict honest records of flight hours...
All The Best
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06-15-2015 02:39 PM  6 years ago
Heli_Splatter

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USA

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maybe rubbing the blades down with a cloth w/dye would pull out the cracks.

What about using x-ray or MRI to scan? MRI might not work as it is conductive.
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06-15-2015 04:38 PM  6 years ago
don s

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Chesapeake, VA

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Very hard to see CF with x-rays. CT and medical accelerator couch tops are CF, because it is nearly transparent to the beam. I could probably play around with the settings a bit.

I don't have access to MRI equipment so I can't comment.
E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.
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06-15-2015 04:40 PM  6 years ago
Aaron29

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USA

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This discussion seems very excessive for what amounts to a mostly nonexistent problem in reality?

If they look good, fly them. If they don't or have been crashed, trash them. It's that simple. Tossing more thought into them is a waste of mental energy.
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06-15-2015 04:42 PM  6 years ago
don s

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Chesapeake, VA

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Bellcranks. E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.
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06-15-2015 06:02 PM  6 years ago
Jeff polisena

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westpalmbeachflorida usa

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I've got blades on helis 12 years old and won't hesitate to hit them hard with no worries . I'm sure if you have analyzing Force flex flux capacitor machine you could prove some fatigue from when they were manufactured . If it was an issue they would come with expiration datesI stole it ,flew it and gave it back ;)
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06-15-2015 08:32 PM  6 years ago
wjvail

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Meridian, Mississippi

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Some number of years ago I had a chance to speak to a then predominant blade manufacturer. I was surprised to find out they didn't have a blade dyno. I had assumed they had some device to test maximum rpm and some method of applying dynamic loads to the point of destruction.

It wouldn't be difficult to build such a device and even if it's not exactly required, I would think it'd be something you'd like to have. It'd be very interesting to run a set of 720's up to 2,500 rpm and rapidly cycle them through +/-13 degrees of pitch for a few hours/days.

Bill
"Well, nothing bad can happen now."
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06-15-2015 10:09 PM  6 years ago
Aaron29

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USA

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I doubt the kind of guy running 2500 RPM and doing McDoogles every day even cares about his blade life. Probably spanks the heli so hard it ends up dirt napping WELL before fatigue sets in.

And if a blade fails under those conditions, it's expected.
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06-15-2015 11:21 PM  6 years ago
wjvail

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Meridian, Mississippi

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I doubt the kind of guy running 2500 RPM and doing McDoogles every day even cares about his blade life. Probably spanks the heli so hard it ends up dirt napping WELL before fatigue sets in.
And if a blade fails under those conditions, it's expected.
I understand what you are saying but I'm not sure I completely agree. It's threads like the one below that will really hurt a company's reputation and if I were making thousands of sets of blades a year and mailing them to hobbyists, I'd like to have some understanding of their ultimate strength.

Given the topic of this thread, apparently I'm not the only one with a passing interest in the properties of our blades not only when new, but also after having been in service a while.

Obviously you can run a helicopter blade company without a dyno. It just seems like it'd be something nice to have.

https://rc.runryder.com/t773921p1/

Watch at YouTube

I might add that destruction testing of rotating parts is not at all uncommon and is often taken to extreme and expensive lengths. For instance:

Watch at YouTube

Bill
"Well, nothing bad can happen now."
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06-15-2015 11:38 PM  6 years ago
Aaron29

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USA

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OK old spinblades notwithstanding.
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06-16-2015 12:20 AM  6 years ago
Jason Cummings

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St. Louis

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Have you not seen the expiration dates on blades?
They're on the inside.
Synergy Field Rep
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06-16-2015 02:47 AM  6 years ago
Nitro Bird

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Tuscaloosa, AL.

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My blades only last as long as my next crash.
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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › How Long Do Blades Last and When do you Replace Them?
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