2 Near Crashes - "Motor Obstucted"

[levancuthbert]

Hey all! I bought my Inspire about 3 months ago, and have flown probably 40-50 times now without any issues, great machine. However, I am out of town for work this week in Evansville, IN so I brought it along to keep me occupied in the evenings.
Tonight I was flying around the Ohio river next to downtown. I was 60 feet over the water, and in horror I see the Inspire start to tumble/flip toward the water. I didn't know what to do except try to push the left stick upward. Miraculously, it rights itself and and hovers. I haul *** toward land and make it to a safe landing. (Granted, with a little pee in my shorts probably). I look it over, install a new battery, but decide to just fly over the grassy area for the rest of the evening just to be safe. I go through another whole battery no problem. On my last battery, I was coming in to land and when about 60 feet in the air, it does the SAME THING. Tumbles toward the ground, and I'm again able to get it leveled out just in time before it lands on the grass a little more abruptly than I would prefer, and tip upside down. I do a CSC shutdown to stop the props from doing a little lawn mowing. No damage, just some dirt on the props.
So I'm back at the hotel now, and I get the flight records pulled up and see that both times...a message pops up "Motor Obstructed", right before it starts to fall. There was nothing obstructing the motors either time. I did a little reading and it seems that when the software detects motor obstruction, it decreases or stops power to the motors?! (Possible Crash Smoking Gun) I am on firmware 1.6.0.40, and have been flying successfully for several months without this error/issue. Has anyone been able to address this issue, or can tell me what I should do (Contact DJI?). I'm really nervous to fly it at all until I can be confident this won't happen anymore...one of these times it will crash and total my precious bird. I have video of the flight record playback if it helps! Thank you!!

 

[slim.slamma]

You probably hit a swarm.
Is what i fear from Motor obstruction firmware should be a user on/off feature.
Not mandated by DJI

 

[eldorado]

Scary stuff. Sounds like you are doing all the right things to prevent an issue.
Suggestion. Take off the props and check everything very carefully for hairs or such. No prop guards, right?

Hair can really mess up a motor and be nearly invisible.

Do all the motors turn easily?

Any bits on the propellers that might interfere?

HealthyDrones.com can make sense of your logs if you need more detail. Highly recommend.

There are mysteries in the DJI software that none of us will understand until DJI publishes the truth tables for their logic.

1. Warning: "Motor Obstructed"
2. Warning: "Propulsions output is limited to ensure the safety of the battery"

These are just two of many we have yet to divine the real causes for.

 

[slim.slamma]

Hey all! I bought my Inspire about 3 months ago, and have flown probably 40-50 times now without any issues, great machine. However, I am out of town for work this week in Evansville, IN so I brought it along to keep me occupied in the evenings.
Tonight I was flying around the Ohio river next to downtown. I was 60 feet over the water, and in horror I see the Inspire start to tumble/flip toward the water. I didn't know what to do except try to push the left stick upward. Miraculously, it rights itself and and hovers. I haul *** toward land and make it to a safe landing. (Granted, with a little pee in my shorts probably). I look it over, install a new battery, but decide to just fly over the grassy area for the rest of the evening just to be safe. I go through another whole battery no problem. On my last battery, I was coming in to land and when about 60 feet in the air, it does the SAME THING. Tumbles toward the ground, and I'm again able to get it leveled out just in time before it lands on the grass a little more abruptly than I would prefer, and tip upside down. I do a CSC shutdown to stop the props from doing a little lawn mowing. No damage, just some dirt on the props.
So I'm back at the hotel now, and I get the flight records pulled up and see that both times...a message pops up "Motor Obstructed", right before it starts to fall. There was nothing obstructing the motors either time. I did a little reading and it seems that when the software detects motor obstruction, it decreases or stops power to the motors?! (Possible Crash Smoking Gun) I am on firmware 1.6.0.40, and have been flying successfully for several months without this error/issue. Has anyone been able to address this issue, or can tell me what I should do (Contact DJI?). I'm really nervous to fly it at all until I can be confident this won't happen anymore...one of these times it will crash and total my precious bird. I have video of the flight record playback if it helps! Thank you!!

Healthy drones can give you some answers!!!
Please share...
Was you recording? Would love to see...

 

[The Editor]

Hey all! I bought my Inspire about 3 months ago, and have flown probably 40-50 times now without any issues, great machine. However, I am out of town for work this week in Evansville, IN so I brought it along to keep me occupied in the evenings.
Tonight I was flying around the Ohio river next to downtown. I was 60 feet over the water, and in horror I see the Inspire start to tumble/flip toward the water. I didn't know what to do except try to push the left stick upward. Miraculously, it rights itself and and hovers. I haul *** toward land and make it to a safe landing. (Granted, with a little pee in my shorts probably). I look it over, install a new battery, but decide to just fly over the grassy area for the rest of the evening just to be safe. I go through another whole battery no problem. On my last battery, I was coming in to land and when about 60 feet in the air, it does the SAME THING. Tumbles toward the ground, and I'm again able to get it leveled out just in time before it lands on the grass a little more abruptly than I would prefer, and tip upside down. I do a CSC shutdown to stop the props from doing a little lawn mowing. No damage, just some dirt on the props.
So I'm back at the hotel now, and I get the flight records pulled up and see that both times...a message pops up "Motor Obstructed", right before it starts to fall. There was nothing obstructing the motors either time. I did a little reading and it seems that when the software detects motor obstruction, it decreases or stops power to the motors?! (Possible Crash Smoking Gun) I am on firmware 1.6.0.40, and have been flying successfully for several months without this error/issue. Has anyone been able to address this issue, or can tell me what I should do (Contact DJI?). I'm really nervous to fly it at all until I can be confident this won't happen anymore...one of these times it will crash and total my precious bird. I have video of the flight record playback if it helps! Thank you!!

Put the props on your Inspire and then grab the motor housing one by one by hand and turn them backwards and forwards. Do any one of them feel stiffer than the rest to turn?
Next time you fly, hover it for a couple of minutes, then fly a few aggressive maneuvers, then land quickly and IMMEDIATELY after you kill the motors feel each one by hand or better still take each motors temperature with an IR thermometer.
If one of the motors is noticeably warmer than the rest I would suspect that as the culprit and could be the bearings worn.
It shouldn't happen on a 3 month old machine but the bearings DJI use are rubbish so it's possible.
Either way, do the tests above and you should be able to narrow it down to a single corner.

 

[damoncooper]

It's worth noting there is a FW bug that kicks up this error when there IS no obstruction.

It's even been seen when using the simulator and sitting still on the ground (motors not armed).

Follow The Editors instructions to be sure you don't have an obstruction, and it couldn't hurt to use your home vacuum hose and a can of compressed air to clean out your motor bells anyway.

Then if nothing else, upgrade to the latest FW.

 

[Mark Poissant]

I wonder if the firmware responsible for a motor shutdown is in the flight controller or is each of the speed controllers making a decision individually?

A fault with a motor, the motor connections or speed control should all be considered.

Your very lucky to still have your Inspire intact.

All the best
Mark

 

[levancuthbert]

Scary stuff. Sounds like you are doing all the right things to prevent an issue.
Suggestion. Take off the props and check everything very carefully for hairs or such. No prop guards, right?

Hair can really mess up a motor and be nearly invisible.

Do all the motors turn easily?

Any bits on the propellers that might interfere?

HealthyDrones.com can make sense of your logs if you need more detail. Highly recommend.

There are mysteries in the DJI software that none of us will understand until DJI publishes the truth tables for their logic.

1. Warning: "Motor Obstructed"
2. Warning: "Propulsions output is limited to ensure the safety of the battery"

These are just two of many we have yet to divine the real causes for.

VERY scary! It made me sick to my stomach for a while after. I do not have prop guards. I plan to order some, but none were on during these incidents. I did as you suggested, used a bright light to inspect for any hair or other debris around all the motors. Nothing found, and all motors turn freely and feel smooth. Thanks for the suggestion about HealthyDrones.com, I may look into that if I'm not able to get much info from DJI.

 

[levancuthbert]

Put the props on your Inspire and then grab the motor housing one by one by hand and turn them backwards and forwards. Do any one of them feel stiffer than the rest to turn?
Next time you fly, hover it for a couple of minutes, then fly a few aggressive maneuvers, then land quickly and IMMEDIATELY after you kill the motors feel each one by hand or better still take each motors temperature with an IR thermometer.
If one of the motors is noticeably warmer than the rest I would suspect that as the culprit and could be the bearings worn.
It shouldn't happen on a 3 month old machine but the bearings DJI use are rubbish so it's possible.
Either way, do the tests above and you should be able to narrow it down to a single corner.

Thanks for the suggestion, I will try these things this evening after I'm done working for the day. I'm very anxious to get outside and figure this out. I do have an IR thermometer at home, I could use it to check the motors when I'm back home this weekend. One thing that just came to mind: I installed the newest props about a month ago (1345T), they've been great. However, one of them has been getting a little tight when trying to remove it over the past few weeks. Last night after these issues, It was so tight I couldn't turn the quick release by hand, I had to use a flat blade screwdriver to pry it loose. I just thought when the props hit the dirt it cinched it down tighter than normal. However, the motor itself on that corner still felt perfectly free, and smooth spinning. I will investigate that corner.

It's worth noting there is a FW bug that kicks up this error when there IS no obstruction.

It's even been seen when using the simulator and sitting still on the ground (motors not armed).

Follow The Editors instructions to be sure you don't have an obstruction, and it couldn't hurt to use your home vacuum hose and a can of compressed air to clean out your motor bells anyway.

Then if nothing else, upgrade to the latest FW.

You are correct, I have seen this "Motor Obstructed" error when I was flying in the simulator before!! I thought that was really weird since the props weren't installed and motors weren't even spinning. You mentioned updating firmware, I'm on 1.6.0.40. I don't see any more recent FW on the Inspire downloads, is there a newer one? Thanks!

 

[damoncooper]

Thanks for the suggestion, I will try these things this evening after I'm done working for the day. I'm very anxious to get outside and figure this out. I do have an IR thermometer at home, I could use it to check the motors when I'm back home this weekend. One thing that just came to mind: I installed the newest props about a month ago (1345T), they've been great. However, one of them has been getting a little tight when trying to remove it over the past few weeks. Last night after these issues, It was so tight I couldn't turn the quick release by hand, I had to use a flat blade screwdriver to pry it loose. I just thought when the props hit the dirt it cinched it down tighter than normal. However, the motor itself on that corner still felt perfectly free, and smooth spinning. I will investigate that corner.



You are correct, I have seen this "Motor Obstructed" error when I was flying in the simulator before!! I thought that was really weird since the props weren't installed and motors weren't even spinning. You mentioned updating firmware, I'm on 1.6.0.40. I don't see any more recent FW on the Inspire downloads, is there a newer one? Thanks!

I think 1.7 is out for Pro.

 

[levancuthbert]

I pulled the SD card from the Inspire and found that I was actually recording video during the 2nd near crash, where it fell to the ground and flipped over. I also screen captured the iPad during the flight record playback for both incidents. Check them out!:
Crash #1 Flight Record Playback:

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Crash #2 Flight Record Playback:

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Crash #2 Video Footage:

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[eldorado]

How fast were you descending? It is possible you had a rotor effect in which the air below the copter is so turbulent from the prop wash that there is no lift.
This effect was the cause of the helicopter crash in the Seal raid on Osama Bin Ladin.

 

[mohansen]

After I got the Motor obstructed error, I was able to bring it back from 4200' and land without issue. As I could not find anything wrong, I sent my Inspire 1 into DJI, they reloaded the same firmware I was running, did a test flight and returned it to me. I am not confident in their troubleshooting or response to my questions.

I did not have any flight issues like you experienced though it does still concern me because I continue to see others with this error.

 

[Predator]

Follow The Editors instructions to be sure you don't have an obstruction, and it couldn't hurt to use your home vacuum hose and a can of compressed air to clean out your motor bells anyway.

Then if nothing else, upgrade to the latest FW.

Shouldn't we downgrade firmware to go back before they added that bs option? Hitting a fly with a motor will basically set a CSC.