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Critical Failure of T*Motor Props during shoot

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There are other variables at play. The ease of move can be affected by smoothness of the surface of the props and the internal surface of the fork where the prop goes to. Tiny amount in any of such variation or tiny burr on the internal edge or a bit of finger grease can change the equation. And from experience the force required to move the prop in the fork can vary with angle too. So, what I am trying to say is that feel might be in this instance more reliable indicator of the proper screw tightness than the torque applied to the screw. The same torque might not necessarely result in the same stiffness of the prop in the fork. The only scientific approach would be to measure the force required to move the prop at a specific distance from the pivot screw. But that is a another thing altogether....
The props have 2 teflon washers that act as sliding surface, but yes I agree it would be best to measure at a specific distance from the pivot point. But barring that, the use of a calibrated torque driver works quite nicely, I have used it and it works. Given the fact that the manufacturer are delivering the props with a specific torque already set (although it is to tight) I think it should be fine. What I am after is a torque value that they recommend, so far no sign of response.
 
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The props have 2 teflon washers that act as sliding surface, but yes I agree it would be best to measure at a specific distance from the pivot point. But barring that, the use of a calibrated torque driver works quite nicely, I have used it and it works. Given the fact that the manufacturer are delivering the props with a specific torque already set (although it is to tight) I think it should be fine. What I am after is a torque value that they recommend, so far no sign of response.
I suspect the reason for not providing the torque value is what I said before. Too many variables. And a new props might require less torque and as the friction points/surfaces wear out they might require a bit more torque to achieve the same stiffness. Also with the late ESC systems applying braking force to motors rather than freewheeling them, it increases the likelihood of out of balance props during those rapid RPM changes and thus increased likelihood of induced vibrations. IMHO the folding props in general are simply not worth the hassle.
 
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Phil, look for a tool that has the range of 5 - 60 cN.m, anything larger would probably not have the accuracy for this size of screws and torque. I can tell you that the props come from manufacturer set to 50 cN.m
Thanks I already looked at some on Amazon and found one that’ll work.
 
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Sadly I don’t know how to post the link on here but if you go to Amazon and type in “miniature torque wrench” several will pop up for you to look at. Sorry I tried to do it but couldn’t figure it out.
Yeah took me some time to figure somethings out myself;)

Depending on what device your using to copy just hold your finger on the link. Then paste on the forum type page.

10;4 I’ll google search MTW.
 
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I would be interested to hear from Florida Drone Supply on this one ...
 

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Greetings everyone - and thanks to all of you who choose FDS as a supplier of any of your equipment. I was out of the office when the initial incident was posted here - but Jim has kept me informed the best he could. I have read the full thread myself and I am going to reach out to the manufacturer tomorrow to see what they say about torque settings. We (like most) have always done this by feel over the years - even on large systems like the M600. We had an Alta for a while as well but I do not recall any of the settings on that one either. I'll gather some info and post back what I find.

@memmi - We are very sorry to hear about what happened. I will reach out to you by email tomorrow to see when you have a moment to catch up about the details. This is the first reported incident of this kind and I would like to know as much as I can about it.

Thanks again everyone for the support and great dialog.

Michael
 
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Do not torque , nope, ALL BY FEEL !!!
If so your going to end up with the same threads as this one..
 
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I think this came down to a QC pass on T motors part that was borderline acceptable or not.

I assume there was a minor fracture / poor acrylic epoxy coverage in that area causing a large stress riser. After repeated flights it finally gave-way.

I myself still fly with single piece carbon props. Folding props are hard to balance and it can lead to laziness of inspecting torque, or prop wobble (not saying you didn't but I am sure there are plenty of pilots with folding props that don't check every flight). With the single piece props you have to unscrew and screw them on before every flight. Gives that extra piece of mind.

I say buy another set and go about your day. First I have heard something like this with these props.
 
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This is very scary......... We use the inspire 2 for mapping purposes over several of our facilities... Having a crash just isn't an option. Is there a good way to inspect these? If not ill take mine off and sell the for half price plus shipping. Only used for four flights... Let me know
 
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Dear Memmi: You have done all of us a great service by being thorough in your comments and documentation. I fly Inspire2 with T motors props. Yesterday, did first photo flight with X7 Camera & 16mm lens. (An aside: In Adobe Lightroom, the lens profiles list DJI with the name: Inspire1 FC350. plus 3 add'l Phantom 3 "profiles" Does anyone know what these profiles mean and why they are not updated? Or do they need updating at all?

Your T Motor prop report is sobering and makes me re-think. I luv T Motors convenience and they seem to fly more efficiently but......the drawbacks mentioned and potential failure isn't fun to read about.. Hmmmm.
 
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Full Disclosure here, I am affiliated with Florida Drone Supply but still post independently as Sancap. That being said I have been a member on these forums since 2013, long before Florida Drone Supply came onto the scene. Since I joined I have posted my opinions based on knowledge and experience.

I was part of the presales testing of the T-Motor props going back to mid summer of 2017 working closely with T-Motor while we found the best design for the Inspire 2. I have used them extensively since then without any type of failure. I can safely say that I have at least 200 hours on them. I complete a very close inspection of them before flights looking for any type of nick or defect on the complete prop and hub as I do with any prop.

I will continue to use them and monitor them for any defects.
 
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"similar issues" as for ALL CF props there is an issue with a slight chip/crack, even small rocks/pebbles that hit the prop (and they will)
go unnoticed. High RPMs - and prop will shatter like a bomb! If you have the budget, replace them ASAP when found @ $$$ each.
@ say $10 the plastic props have NEVER failed me, never! The performance of the CF is very minimal compared to the plastic props, tho the ego of having them on the bird is another story. :rolleyes:

I'll take the plastic props any day of the week and place the saved funds in my righthand pocket! That's just me... :cool: and there is no way I would place those remaining props back on the bird. Stress cracks, a chip, you name it! Nope-nada-no way! As I'm looking at the pic, this could have been the Oh-Sh*t of the motor mounting issuse that's been plaguing the i2 also.
Ya know what they say, opinions are everywhere, everybody’s got one. Just saying that I use them and have never had a problem and the ease of deployment is far greater than $$$$. And as long as I inspect them before and after each flight I feel very comfortable and confident using them.
 
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Full Disclosure here, I am affiliated with Florida Drone Supply but still post independently as Sancap. That being said I have been a member on these forums since 2013, long before Florida Drone Supply came onto the scene. Since I joined I have posted my opinions based on knowledge and experience.

I was part of the presales testing of the T-Motor props going back to mid summer of 2017 working closely with T-Motor while we found the best design for the Inspire 2. I have used them extensively since then without any type of failure. I can safely say that I have at least 200 hours on them. I complete a very close inspection of them before flights looking for any type of nick or defect on the complete prop and hub as I do with any prop.

I will continue to use them and monitor them for any defects.
Thanks for your input Sancap! As always!
 
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Thanks everyone for your feedback here. I’m glad it *seems* to be an isolated issue and I’m hoping it stemmed from something avoidable, like damage sustained during transport instead of a manufacturing defect or failure due to the load.

I’m conflicted as I have a full quick launch setup based around the folding props for my 2 weeks flying at burning man. The time lost going back to regular props is significant.
 
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Thanks everyone for your feedback here. I’m glad it *seems* to be an isolated issue and I’m hoping it stemmed from something avoidable, like damage sustained during transport instead of a manufacturing defect or failure due to the load.

I’m conflicted as I have a full quick launch setup based around the folding props for my 2 weeks flying at burning man. The time lost going back to regular props is significant.
I understand your quandary about going back to using stock props. They are a huge time constraint especially when you’re having to get ready quickly for your upcoming shoot. If I were you I would order another set of the Tmotor props from Florida Drone Supply and I’m sure they would be able to get them to you in no time. I have been dealing with them for quite awhile and they’ve always been timely with their response times. Good luck on your upcoming work.
 

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Interesting thread. I fly the I2 and have only used the stock props. About a month ago I found a hair line crack in one of the props. The I2 has not had any accidents, props haven't hit anything that I'm aware of there were no leading edge nicks or damage.
The I2 has a little over 140 hours on it and these were the original props. I replaced all four props and also carry an extra set.
I have been around aviation most of my life, I'm almost 70 and I learned long ago pre-fligh inspections are critically important. As already stated, almost anything can fail, and some with no warning or signs of potential failure.
I was to ferry an brand new Cessna many years ago. I was about to rotate when the continental engine decided to come apart. That was a brand new engine but Cessna didn't discontinue using the continental engine, they realize that sh.... happens and that is just life.
The T props may be well tested and good props, but once you have been bitten, it's pretty hard to trust the old dog.
 

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