Speaking of fan blades........
I had a tenant at our diesel pusher only storage several years back. Owning a mid 90's Prevost he hired a crackerjack mechanic to change out his engine cooling fan from metal to nylon or fiberglass. The lighter weight thus better fuel mileage. Makes sense to me. Orders fan, finds mechanic ....…What could go wrong with this simple job ????
First off the replacement does not match up to bolt pattern so that needs to be exchanged. With the now correct fan ( 2 weeks) received the new one is ready to be mounted in place. Waits again for mechanic now working on another part time job, another 2 weeks.
All set for better mileage, and stocked for a vacation, family, dog, kids off he goes... sort of..... overheating about 5 miles from the bus barn. Turns out the blade angle was reversed from his original metal fan blade. Of course the blame game was in full mode by the crackerjack mechanic who for some reason (lazy comes to mind) never laid the original with the replacement side by side and refused to do the job again without being paid before hand. How things can go landslide wrong.