Another Original 2-Blade Fan Takes Its Toll

[Terry, NJ]

Originally Posted by Bill Goddard

OK. Time for my 2 cents - maybe 1 cent. What would the group think of a life limit on fan blades. Maybe 5000 miles. Helicopter rotors are limited by max no. of hours because of the alternating flex problem. I would think you could get 5000 miles on a NEWLY manufactured fan.
Also - if the new sheet metal fans are formed at the base with a shearing burr on the outside radius of the curve there is a real possibility of a crack developing along that edge. I would check a new blade for this burr and file and polish the edge real smooth if I found one.

Bill, I think you're trying to solve a perpetual problem by applying the most draconian answer. Actually, the mod A is the first car I have ever heard of exploding fans on. All my cars and trucks are run to well over 100K miles and I have never had a fan let go. Why are mod As the only cars affected? I should think that the four blade steel replacements should solve this problem, if not, why? My own theory is that Ford made the pitch angles too steep and this cause too much flexing at the higher speeds. This would cause the metal to crystalise and fail. I'm very new to this so maybe I'm talking thru my arse. Let's just convert to stamped steel 4 blade and move on.
Terry