From what I've read, at first the Curtis electric props were difficult to maintain.....
Not only the prop itself, but the whole separate electrical system that went with it, individually, on each engine.
Hollow steel blades were severely prone to cracking, and if one let go, you could say goodbye to the whole engine in a heartbeat...as in, torn right off the wing.
Malfunctioning large propellors can be
very serious business, and need to be treated with utmost respect....least you end up quite dead.