I have flown my drone a couple of times,notice a prop kept popping off,3 of them self lock and the other one doesn't lock in,anybody know what this could be from
Either check the hub of the propellor for any cracks or carefully inspect the retaining spring on the offending hub. It should be fairly obvious if you compare that particular one against the others. You may want to consider upgrading to the new style of hubs available from dji if you are running an older style of retaining clip assembly.