Critical Failure of T*Motor Props during shoot

RBP said:

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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Phil DeVore said:

I agree with you that people are making this issue way too complicated. It’s simply a matter of feel when you’re tightening the props. Kinda like when you’re replacing your tire after having had a flat. Just don’t strip the lugs when you’re tightening them down. Same idea here too.

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FlyaDrone said:

One consideration for all of us using foldable props that are securely attached to the I2. Inspection of the blade undersides is problematic. I carry and often use a magnifying glass to help identify any micro cracks or fractures which might be difficult to detect without magnification.

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memmi said:

Firstly let me state my positive experience with the T*Motor Folding Props for Inspre 2. I’ve used the folding T*Motor props actively since their release. I’ve appreciated the speed at which I can deploy the inspire from the LowePro drone guard pack and traveled from Tulum to Iceland and beyond using this combination. I also want to acknowledge Florida drone supply as a responsive retailer and active partner in this space.

In Brooklyn last weekend was flying the X7 for a shoot at a densely populated large scale venue at night (with applicable night waiver). Our 5th flight, around midnight, launched from a protected elevated platform. Immediately after launch a loud crack was heard and from about 6 feet above launch elevation the inspire went spiraling into the ground breaking the rear leg motor mount housing and all remaining props and the Imaging system on the Inspire 2.

Upon inspection one of the props cracked and sheared off from its pivot. The ejected half was not recovered. I constantly check the torque on both the prop bolts and the motor bolts and they were all appropriately torqued. There were no prior collisions or damage to the props, the full set was under 2 months old.

As it stands I appreciate the performance and convenience of the T*motor props and was looking forward to active use during Burning Man this year. However, I wanted to communicate my experience as a data point and a warning that as far as I can tell, the t-motor props under normal use have the potential for catastrophic failure.

I'm open to input and would like to hear if this is an isolated incident or if there are other similar issues. Am I wrong to no longer trust this product?

Video of the shoot at:
Mayan Warrior (@_mayanwarrior_) • Instagram photos and videos[/Q same here. went back to DJI props

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r62ewa said:

I lost my I2 using T-motors this week. From the factory the blades are very tight and hard to open, so from reading here it is recommended to loosen the bolt a little to make the blades a little easier.

I guess I loosened mine a little too much as during the end of my flight I was returning to land and one of the blades came off at about 100ft elevation. The I2 with X4S came down and landed in about 3 feet of salt water. A total loss and write off.

I am going to be sticking with the stock set up from here on out, even with the red prop rattle. An expensive $5400 crash. I have a full brand new set of T-motors I had as backups that will never get used.

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MrTVR said:

Did you recover the blade that detached and were you able to identify the reason it came off?

Was it just that the screw fell out or was it due to some form of failure of the blade itself?

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r62ewa said:

I did recover everything and it was the screw had worked out. Kind of hard to understand why as the screw was still down through the top of the blade mount but out of the hole at the bottom of the mount where the threads are. Given how wide the end of the blade is where the hole is for the screw, I thought the screw would have had to come out completely for the blade to let go, not have the screw still in the top hole and just not in the threaded lower part.

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MrTVR said:

I guess that once the screw has come out of the lower thread then the blade will effectively spring open the mount due to the upwards forces on the blade.

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MrTVR said:

I guess that once the screw has come out of the lower thread then the blade will effectively spring open the mount due to the upwards forces on the blade.

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mmarian said:

That does sound like a plausible assumption to me. I do not have those props but isn't there a locknut on the bottom and if not why not?
Edit.
Just looked at the design and there isn't one!!! That alone would make me not wanting them, full stop! To me this is a critical design flaw.

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cougar said:

Not correct, there is a self-locking nut. Must have been backed out of the screw to far out of the locking part of the nut.

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mmarian said:

That is good to learn. So, the locknut is hidden in a recess in the bottom plate, right? Then the only possibility is that the screw is simply not long enough to prevent what you have alleged has happened from happening.

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cougar said:

You are correct in that the locking nut is in the bottom plate. The screw does go threw the locking nut, I think the poster simply backed out the screw too much, hence out of the locking part of the nut.

When we are talking about backing the screw out we are only talking very little, less the 1/10th of a turn. Hence why I have been talking about torque values.

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mmarian said:

Only playing a devil's advocate here but if he did that wouldn't he has noticed that one half prop was loose, very loose and the screw was dangling up and down?? If the screw goes right through a locknut, it needs to be unscrewed at least 2mm to get out of the nylon locking part. This seems like highly unlikely scenario to me and one which could hardly go unnoticed.

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r62ewa said:

I just inspected the prop that had failed. The nut is recessed in the bottom but it is not a locking nut of any kind, it is a standard type nut.

Also, I just put the screw in to where it would normally sit, it took me 8 full turns, yes 8, to get the screw to disengage from the nut. When I loosened the screw I was very nervous of it being too loose and only slackened it enough to get the blade moving a little easier, it was by no means close to one full turn, let alone 8!

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mmarian said:

Only playing a devil's advocate here but if he did that wouldn't he has noticed that one half prop was loose, very loose and the screw was dangling up and down?? If the screw goes right through a locknut, it needs to be unscrewed at least 2mm to get out of the nylon locking part. This seems like highly unlikely scenario to me and one which could hardly go unnoticed.

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