Small change in sound but no obvious problems?

[AllanM]

I recently had a small crash when the P3P flipped onto its front 2 rotors while landing. No obvious signs of damage and all was fine. I cashed it again from about 1.5m off the ground when it clipped a bush in thick forest, again no obvious signs of damage and it all worked fine. However, we noticed a very slight change in the pitch of the sound when it took off next, we flew it for another 2 or 3 hours over the next couple of days without problems and it all seems fine. I can't help having concerns about what is causing the tiny change in sound. I have tried listening to the engines carefully, and I cannot hear any difference between the engines. No obvious sounds of bearing or other problems. Could it be just the minor scratches to the rotor blades themselves that made the change? I have a spare set of carbon fiber rotors but I figure they could sound different anyway so not sure what to do. All seems fine.
Anyone with any thoughts on this?

 

[With The Birds]

Given how cheap and critical to performance they are, prop replacement after a crash is a no brainer.

Replace all four with the same props you are used to. That should get you to the benchmark for the "normal" pre crash sound and a good starting point for further throubleshooting.

Check the motor attaching screws are evenly torqued and you dont have cracks in the arms. Rotate the mitors by hand and feel for any binding or inconsistency between motors.

Make sure the shell is fitting together nicely. Something as simple as one of the clips that holds the halves together breaking off and vibrating inside the shell could create the change in sound.

Watch clisely for any changes in flight. Even things like reduced flight times on known batteries can be a clue that something isnt right.

 

[AllanM]

Thank you very much, everything else seems ok so I'll try to get some more normal rotors to try.