Technical Catastrophic water pump failure

My comment is that I have not seen that much damage on a roadster before. Maybe none had side panels but I hadn't seen anything other than radiator damage before. I'm glad nobody was hurt.

 

I wonder how the material thickness, of the broken aftermarket fan,
compares to similar OEM designs. Because you know bean counters
like to make stuff thinner, to save 5 cents per 100 units.

 

I beg your pardon??? How rude. Our seasons are just fine. It is yours that are back to front.....

 

Big mass fan, pulley as mentioned.
Add belt load pulling down.
Fan is straightening lifting up fighting belts.
Fan blade shows existing Crack signs. (Just saw previous post)

Mohrs Circle... diagram..on loading after fan blade failure. Looks like casting failure started between lower bolts, high stress from fastener location.

Improve, rebuild, get it back on the road.

 

Smooth to rough.... fan was cracked. Smooth is Beech Marks..existing Crack.

 

I bought this ancient belt driven fan, that was part of a water passage from some type of industrial engine, years ago at the Portland swap-meet.
It has a bearing housing that is a oil reservoir. When I saw it at the swap-meet, it was just spinning freely in the wind.
Paid $3.00 for it.
It's just a cool unit that sits on my front porch, doing it's thing.
The thickness of the metal on these blades, is testament to how well the old stuff was made, built to last a lifetime.
Everyone's results may vary greatly!

 

It wasn’t the water pump.

 

Heavy Duty like old farm tractors....

 

I have Grundy and they would cover this.

 

Another reason to like clutch fans. These limit maximum fan speed to about 4K RPM. Yeah, they're hard to package in some cars, but worth it IMO if you can make one fit.

 

I purchased the Zip's water pump setup ages ago when everything was cast iron along with the water pump thinking that the aluminum version would look better. Newer isn't always better.

 

The Aluminum pump was killed by the broken fan.
Agreed, a cast iron pump would have stayed together, most likely.

 

had one let go in my old 56 BelAir. sent it right through the hood so I hammer and dollied it into the shape of one louver

 

Several years ago at our airport we had a three blade propeller assembly show up that was off of a King Air. One of the blades had broken off within two or three inches of the base. These propeller blades weigh roughly 25 lbs. or so static, so you can imagine what the centrifugal weight is when they are spinning. The pilot told a co-worker how the prop blade separated from the prop hub during a flight and in the few seconds it took him to shut down that engine it almost shook the engine off the wing. They were fortunate that the blade didn’t go through the aircraft and instead sailed off into the air. If it had gone through the aircraft it likely would have brought the plane down. On a good note, I’ve never seen or heard of another instance of this happening in general aviation, many failsafe measures are in place to stop these kinds of things from happening.
As others have said previously, I believe Squirrel is right on the money in his analysis.
This fan blade is a similar situation to the propeller on a smaller scale. One reason why I always try to stay out of the line of sight of fans when timing an engine or performing some other similar task. The chances are slim, but as your experience shows, it can happen.

 

Returning to work from lunch one nice day, I had 2 blades and their portion of the hub leave the 5 blade fan on my Fury's 318. The imbalance was incredible.

The chunk lopped the bottom corner off my battery just big enough to allow a slow drip to overcome the surface tension of the acid.

After removing the corner of the battery, it karate chopped the factory steel brake line crossing the top of the frame, flattening it a good bit, but not closing it off.

Removed the fan and drove it home from work that summer day-all highway, so it cooled fine. considered myself lucky.

-rick

 

So the blade that let loose wasn't the only problem? Looks like the whole thing was soon to go off. Someone pulled the pin out of that grenade! The small bang was big enough....

Chris

 

Late seeing this thread. But as the old HAMB metallurgist, I can tell you that is a fatigue crack on the missing fan blade. You can see the basically smooth elliptical shape of the fatigue crack propagation in the dark area. 100% classic fatigue crack appearance. If you follow the propagation back to the initiation point you might find a stress concentration of some sort. That may take magnification better than a simple internet picture. The clean rough area is the final stage overload fracture, where the remaining portion exceeded the tensile strength. Technical term is dimple rupture, which is a ductile overload fracture.

 

What would cause the stress concentration?, poor design, overspeeding ?
Thanks
Dan

 

Stress concentration could be almost anything. Rough spot on the surface, a scratch or machining mark on the surface, a small defect in the material. Basically anything that makes the localized stress in that area higher. But remember that a fatigue crack is below yield stress propagation. It takes many thousands of cycles (several hundreds of thousands typically) to initiate and propagate the crack. A fan flexes as it reacts with the air on the blade, plus it also has the centrifugal force pulling it. Lots of source for stress.

 

Thanks
Dan

 

Google: Stress Riser.

 

Truly amazing account of gear box failure that caused the prop to slice through the belly of the aircraft, shortly after take off. Major decompression and no one was hurt!
This event happened on June 8th, 1983, the plane made a dramatic landing in Seattle, the footage of it is incredible!
Check out this incredible story on YouTube.
This is just a screenshot, so you can look it up with a web search.
Thanks from Dennis.

 

I understand stress risers, but unless the OP nicked or damaged the fan during installation any stress riser that caused the failure should be the manufacturer’s responsibility. If the OP exceeded the recommended RPM of the fan I can see that starting the crack. The OP had approximately 4000 miles on the fan, surely that amount of run time shouldn’t have approached enough cycles to cause a failure. I would think that 100,000 miles would be an absolute minimum before failure. Good design and engineering practices should dictate a fairly high factor of safety to guard against such a failure. Hopefully the manufacturer stands behind the fan.
Dan

 

I would expect the process of manufacturing that fan to be either a single or two-step process; if two, a flat sheet is cut out and then thrown into a stamper to give it the fan profile, flung into a bin, hung up for paint, baked and boxed.

Doubtful the stamp-cut edges are feathered, so any slice like that will cause small score marks to be present on the edge, along with a curved top shear edge and slightly rough break on the back.

Gentle cleaning of the paint on the same area of an unbroken blade will show how much care went into the production of the piece.

 

...are often over ruled by Bean Counters, who know nothing about design or engineering.

 

I know a guy that this happened to. Just barely got to keep his arm when the surgeries were over. Good reminder for all of us to inspect old fans.... With the engine off.

 

My failure analysis background agrees.