Monday, October 13, 2014

Flight # 6 - Crash Landing - Damage Evaluation

The good news is that all electronics seem to still be working. On the bench, I connected a LiPo and used the Taranis and DroidPlanner. I can Arm and spin motors, instrumentation sensors are all working, etc.

Lower shell only 60% cracked (but mounting point is damaged). Notice oval copper solder-pad ripped from ESC.

Upper shell 100% cracked. Screw mounting point compromised.

Top and bottom body-shells are pretty much trashed unless I try to glue them back together. I would like final repair to look acceptable, but more worried about structural integrity since it is a motor arm and shell is also the frame.

ESC damage. Not sure what PCB Revision this is, but I think it's older (ie v1.0).

Scratched SMT micro-trace and soldered on jumper wire for testing. It worked but didn't hold. Notice trace lifted from board but stayed connected long enough for testing.

The PWM solder-pad oval got ripped right off the ElectronicSpeedController (ESC) PrintedCircuitBoard (PCB). I did a very-temporary micro-solder-hack to make sure ESC was still working, and it is. However, all the PWM traces are SMT form-factor, so re-acquiring that trace (on either PCB side) will be tricky. There appears to be several different "MFL1218" Nova/CX-20 ESC PCB Revisions and but the word in the forums is that they can be mixed in the same aircraft and work (calibrations, actual operation, etc.). Appears to be a simple 2-layer PCB.

PWM detail. Under the letter "W" signal uses a hole-thru Via to other PCB side. All the way back, PWM trace is about 50% width of a normal trace like the 5v one pictured here.
Not sure what is risky-er ... trying to fix this one and use it or trying to integrate a different revision one. Also, a new ESC is $35 shipped (from Hong Kong and the wait). One possible way to fix this one (and it be durable enough) might be to cut the 5v trace toward middle of PCB, jump to it near Via hole, and use it's pad instead (5v trace/pad isn't being used). Actually, as I examine under the QC-1 sticker ... this version doesn't appear to have 5v capability, so the 5v trace isn't connected to anything on either end.

It came to rest like this. It was still on and knew it had landed. I don't think landing in the tree caused much damage, rather it was the Nova hitting the ground under the tree. In addition to the Body and ESC, one prop-guard was broken and twisted beyond repair. Three of the props were nicked but none had broken blades. Prop-guards seem to do their jobs ... absorbed crash energy, and likely prevented even more damage to delicate parts (ie motors).

The repair starts here.


  1. Hi, I've notice that there are some solder drops in all my ESC in this normal?

    1. If they work, probably ok. I would have to see clear close-up pics to say for sure.


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