[Earle]

Point well-taken, Marco. These fans, now 80 years later, technically met their "design life", whatever that was in the designer's mind at the time, given the relatively few miles the cars were driven back then compared to modern cars. But if the cars had been driven anywhere near the number of miles we rack up today, the epidemic of fan failures would have begun in the 1930's instead of 70 or 80 years later. Their fatigue life depends on the number of hours of operatin (cycles) not the number of years gone by. Henry lucked out with the decent service the fans provided over the "average" in-service life of a Model A at the time. He likely did not imagine that A's would still be in use 80+ years into the future - and couldn't have designed for it even if he did know. It would have to have been a trial-and-error testing process, if this fan design was even tested pre-production at all.

These fans had an undefined, "limited life" with safety implications at failure. But this concept wasn't something that auto designers concerned themselves with back then.

As an example of a different design philosophy....In aircraft design, flight safety is everything. When a part cannot be designed with "infinite fatigue life", a very conservative analytical prediction must be made of its operational life span. Then, when that time is up, no matter how good the part looks, it must be replaced with a new one. The aviation industry at that time didn't even fully understand designing for fatigue and many people paid with their lives.

To install a safety-critical, limited-life part (like this fan) on your car today with no idea of how many hours (cycles) of operation it has on it, is very unwise. Even if you knew the exact number of operational cycles the fan had on it, it would be impossible to predict how much life it has left in it.

Oh well...Fun discussion but too deep in the weeds. Bottom line - don't use an original fan on your Model A because you're on borrowed time on a dangerous, life-limited part.