I’ve never heard or read of this happening to anyone else, so thought I’d check in with the forum.
Last spring we were anchored in the south Alligator River waiting for the winds to drop enough to let the Alligator Bridge open when we heard a very loud BANG! Running up the companionway
my first thought was that we’d been hit by another boat, but looking around I saw nothing. It was then that I realized that the wind generator
was no longer making any noise
, a rare thing for our old Air-X in this much wind
, about 22 knots at the time.
Peering out from under the bimini
revealed that one of the Air-X blades had indeed went for a fly-by of the anchorage on its own. We were at once lucky and unlucky that the blade had flown off leaving us without “free” power, but its trajectory hadn’t been through the boat or crew. Thinking about what could have happened had it sliced down into the cockpit
while we were there made me shudder.
It wasn't until we stopped in Hampton, VA, that I was able to remove the nose cone and check things out. Wow! The two remaining blade roots were broken into three or four pieces and being held on by the tiniest grip of one bolt.
What could have caused this to happen? True, a few days previous we had been through a night of 40-50 knots off the Georgia
coast, but the wind
gen was turned off and the blades should have just been idling away like they usually do when the gen is switched off. I wasn't looking at the time, but assumed that was the case.
Removing the hub, and then the blades revealed what may have been the problem. There was a fairly large amount of corrosion
residue under the two remaining blades. This was probably caused by the blades being fastened with stainless steel
bolts to an aluminum
hub with out benefit of super lube or other isolating product. I'm guessing here, but I suspect that the corrosion
enlarged the holes slightly and the residue that built up under the blade perhaps warped the blade slightly. Combined, they caused the damage. Does this sound right?
I was going to replace the blades with some of the newer, supposedly quieter ones, but the offer of an older, unused set for free changed my mind and, after cleaning
up the old hub they were installed and ready for a wind test. Which it failed. Too loud, and way too much vibration. Down they came and after balancing them they went back up, and what a difference! They are so much quieter than the old ones I can hardly believe it. So now I'm thinking that I have to add - out of balance blades - to the reason for the blade coming off. I should add that the Air-X has been on the boat since we bought it five years ago and have never had a problem with it, but have also never done any maintenance
to it either.
Anyone else out there have this happen to them? Any other thoughts as to why the blades failed?