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Prop Service Time Limitations

BigNutz

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In light of a nearly certain total loss of an entire airframe if a propeller blade develops a hairline crack which goes undetected on any model sUAS, are there any corporate UAS programs, Commercial Drone Service providers, or even just individuals who time or cycle limit the propellers of any of their aircraft.

Having worked in manned aircraft maintenence throughout the years where these types of life-limiting metrics had to be tracked and complied with. This would certainly be the case for any part or component which spun as fast as these props during nominal use, represented a single point of failure with no redundancies, and/or the failure of would result in the complete liss off control, the aircraft losing it's capabilities to remain aloft, and would be expected to suffer catastrophic levels of damage to the aircraft.

So, I'm fighting the impulse to start wasting a bunch of these rotar blades!
 

R Martin

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In light of a nearly certain total loss of an entire airframe if a propeller blade develops a hairline crack which goes undetected on any model sUAS, are there any corporate UAS programs, Commercial Drone Service providers, or even just individuals who time or cycle limit the propellers of any of their aircraft.

Having worked in manned aircraft maintenence throughout the years where these types of life-limiting metrics had to be tracked and complied with. This would certainly be the case for any part or component which spun as fast as these props during nominal use, represented a single point of failure with no redundancies, and/or the failure of would result in the complete liss off control, the aircraft losing it's capabilities to remain aloft, and would be expected to suffer catastrophic levels of damage to the aircraft.

So, I'm fighting the impulse to start wasting a bunch of these rotar blades!
We use a set of props for 1 year and then discard them. Part of our annual maintenance program. Props (or pairs of props) are cheap considering the replacement cost of the aircraft and camera.
 
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Airmapper

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When I was researching the Yuneec H520 the manual had a statement about replacing every 20 hours. I thought that was probably wasteful but since it's in the manual if you operated that unit I'd say you have to follow it or else you would have a lot of explaining to do if it ever had an accident. That said the H520 is a hexacopter and is touted to have the ability to detect a blade loss and fly on 5 blades if it needs to, so that in itself seems redundant, but aviation loves redundancy.

My worry with Yuneec is getting extra blades and the cost......

Personally when I created my maintenance procedure for my Mavic 2, as it conveniently didn't have any real detailed procedures that I found in the manuals, I left any statements on replacement pretty vague but made inspection a priority. My pre-flight inspection includes a prop inspection and my maintenance inspection interval is about every 3 months or 20 flight hours, whichever is more proactive, and details removing the props for a detailed inspection and replacement if any issues are noted.

In practice my plan is to replace the set any time I find the slightest indication of wear or damage, as there are ample options for the Mavic and a set is an easy to swallow ~$20.

Beyond failure I'd see replacement at the slightest sign of wear as benefiting efficiency and battery life. Probably minuscule, but once the blades show any signs of wear or the slightest nicks, I bet they are not moving air as well as when new. Besides it's hard to know what stresses the blade has experienced, I'd just replace it.

One thought I had on used blades is I bet some clients might find them nifty trinkets. Put your info on them somehow and keep them in the vehicle, give them away like business cards if you meet a potential client you get a vibe they would be intrigued by it, like someone you notice really checking out the aircraft or seems otherwise impressed with the technology.

But take my comments with a big grain of salt, I'm working on being in business, but I'm not actually in business yet for full disclosure.
 
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R Martin

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When I was researching the Yuneec H520 the manual had a statement about replacing every 20 hours.
Two points of perspective:
1. Most of my flights with our smaller aircraft last minutes. 90% are under 15 minutes. So potentially I would still wind up replacing my propos about once a year or after 20 hours of flight.
2. 20 hours is the manufacturer recommendation. You should establish a maintenance program to cover this. You should also be doing thorough inspections before each flight at a minimum, and after each flight is also a good rule of thumb to detect potential problems and get them fixed before a preflight inspection grounds you.

As a rule we keep an extra set of props on-hand as spares to cover an oopsy. If you see cracks developing or nicks on the ledging edge before the maintenance cycle calls for replacement, then replace the prop. If the prop starts fitting loosely in the locking collar, then replace the locking collar and/or the prop. Common sense stuff. Do your inspections. This is ONE more thing to keep an eye on. There are a lot more....
 
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Dave Pitman

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Eventually, I think we will see some kind of worthwhile direction on this. But, until then, think it is difficult to put any "rule of thumb" on current consumer props. I think replacing them when you know there has been a stress event. Or, if there is any detectable defect goes without saying.

But, just assigning an arbitrary figure like time or hours would just be guessing. For example, if it's just time, then who is to say that the "new" ones you purchased to replace the "old" ones haven't just been sitting on a shelf somewhere and are not actually any "newer". In fact, they may have been sitting on a shelf in a cold location freezing and getting brittle rather than in your environmentally controlled hanger. Picking a # of hours is fine but can be problematic for the same reasons.

I would welcome if the manufacturers put in a little effort to do a little research and supply some science based guidelines. But until then, we just have to guess, and/or roll the dice.
 

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