What usually breaks after a crash?

[davewilliams]

I crashed my P3P recently and invested some $ in a new shell and replacement gimbal ribbon.

Aside from obvious visible damage to a crashed drone, what typically breaks internally? Since most of what's inside is solid state, are there particular solder joints that break?

Someone mentioned that motherboards usually are irreparably damaged in a crash. I ask because I'm trying to figure out whether to continue poking around internally or to put the drone up for sale for parting out.

Thanks in advance for any and all answers.

 

[JeffreyS]

So, is the drone working correctly? Never stated such. That's what counts.

 

[BigL]

What usually breaks after a crash?​

your bank account

 

[davewilliams]

It doesn't work yet. It'll power up, etc. But before I move on with installing the new gimbal ribbon and re-attaching the gimbal and camera (not fast tasks) I'm trying to figure out whether those two tasks are worth the effort. In other words, if it's likely the motherboard or something else internal and critical is broken, I'm just going to part it out or give it away to a local STEM program.

Thanks in advance for any advice or insights.

 

[dirkclod]

What usually breaks after a crash?​

your bank account

That and my heart

 

[quaddamage]

What usually breaks after a crash?
your bank account

But seriously, the answer is - Gimbal. That is the most fragile and most expensive part.
The gimbal has few weak mechanical spots which usually get affected, and that protects most of the electronic part.

And on second place - is the landing gear. But that is plastic, cheap and easy to replace.

"but what exactly" - I'm pretty sure would be the next question. So, in the order of force of impact:

- The plastic mounting plate / cross plate / dampening plate on top of gimbal - it is there to break and absorb energy of impact, but that's rarely enough
- FFC of course
- Gimbal-to-OFDM ribbon - it often gets some ripped connections; can be put together without replacing, but the molex plug will no longer hold all the wires when unplugged
- motor shafts - the aluminum gets bent near shafts, making tumbling and wrong movement of arms; if the arms are rickety enough, the gimbal won't stabilize at all
- aluminum arms - the aluminum gets bent near bending points, making the gimbal unable to direct straight; trying to straighten that will cause the arm to break
- aluminum arm limiters - each arm has some kind of mechanical limiter for movement - usually kind of bolt; without it, the arm will move further, putting stress on FFC
- A specific quartz oscillator on Gimbal Top Board - when the drone crashes down in its normal orientation, first the plastic plate breaks, then the ribbon gets ripped, then the lens part reaches the ground and that puts pressure on all arms. The Yaw arm gets pushed towards the electonic board, and there is one component there higher than all the others - the long XLAT. so it gets squished, breaking the crystal inside.

Btw, some companies are selling various "strengthening packs" for gimbals. Primary school physics should be enough to know attaching any more mass will only make things worse on impact. The energy of impact needs to go somewhere, it won't magically dissolve into air. And the higher the mass, the larger the momentum, which when negated at the short period of impact releases larger energy.

 

[davewilliams]

Thanks so much for your thorough answer, Quaddamange. I'm going to quit my attempts to complete this repair. Doesn't seem worth the time and effort to figure out what else is broken.

I guess I'll try to sell the crashed drone for parts. Shame of it is the controller and five batteries are still good. And the controller contains an HDMI output module.