Replace both propeller blades or just one

[qchen]

The instruction says that I'll need to replace both propeller blades even if only one was damaged.

Is it just a way in which DJI scams your money? I do not believe that mini's propeller blades are shiped in pairs after being balanced at the factory.

 

[FoxhallGH]

Welcome to the forum ...
That could be a hang-over from the other DJI Mavic drones, as they have prop's which have blades connected to a common hub. It is possible to replace a blade on that type of hub, but not recommended, as it can weaken the prop. However, the Mini uses a different type of prop' set with individual blades. I'd expect the production quality to be more than sufficient to allow you to replace just the broken blade in a pair ... HOWEVER - if the Mavic has been in a position to damage one blade, it is highly likely that the second blade following close behind has also hit the obstacle (what-ever), and sustained damage. That's the logic in the 'replace both' argument ...
The bottom line is - are you prepared to lose your drone for a couple of dollars worth of prop's???

 

[Bjord]

I don't think DJI is trying to scam anyone, I think they are just playing it safe.

The blades need to be as symmetrical as possible for balance reasons. I believe if they are not balanced then you might run into lift issues or extra vibration which could lead to damage.

There could be any number of reasons why two propeller blades may not be alike. I have a few guesses:

• With normal use, the blades might warp slightly over time. The same two blades will warp at the same rate so they would stay balanced with each other, but if you combine a new blade with an old one you might have a balance issue.
• Word around the internet is that there are about a dozen different models of propeller for the mini. I know that my fly more kit has propellers with different model numbers on them. If these models are slightly different in shape, you might run into balance issues by mix and matching different models.
• It might be that newer sets of propellers (either now or in the future) have a slightly different shape, due to intentional changes or variation in production, and they are proactively telling users to switch both blades just in case.

 

[hashfly]

I'd follow guidelines on maintenance regardless of how you feel about them personally. If you were to have a crash and had only changed one propeller at some point, then improper maintenance would have to be taken into account.

Per FAA guidelines here in the US I keep detailed records of maintenance on my drone. Despite being a mini, putting an object into our national airspace carries a lot of liability and responsibility that I feel most do not appreciate.

If something bad were to happen the onus of proving the aircraft was airworthy at takeoff is on you.

Having proper maintenance logs that follow manufacturer guidelines can only help your cause, not following them can have consequences.