Disaster! Avoided. Had I not heard the clicking noise coming from my Enertech 1800 last winter and taken action for sure I would have had some horror pictures to blog of the unit folded over with its blades smashed against the tower. It was close to failure. I was able to break off this third of the support with a vise grips.
So first up was the repair to the main mounting plate. A 3/8" thick plate was bored and welded to the cracked original. The the cracked areas and hole for the power cord welded. Plus new stronger brace pieces welded in. Looks very, very strong.
Next was the repair aka "fix" to the blade mounting plate. The design of a single 1/4" thick plate with flanges bent to stiffen it was not a good one. All the stress from the blades was concentrated on the 3 bolts that attached it to the center hub. They used 1/8" thick 1" diameter washers to help but it was not enough. The original plate, 15 years ago, had the same cracking failure around these bolts and here it was again. What to do? Belt and suspenders! I cut and drilled a new 1/4" plate that was welded and bolted to the original. Plug welds and edge welds were made. Six grade 5 bolts were threaded and nutted along the welded edges. Finally 1/4" thick 1.750" diameter washers were made and fitted for the 3 hub bolts. Belt and suspenders!
Then it was on to the blades. At first I thought the wear at the holes was a big problem. After some discussion it was determined that the holes were most likely drilled out to make them fit the plates that secure them. This was backed up by two of the blades having different ID numbers. However the splitting along the grain was a concern to me.
I decided to drill cross holes at the bottom and install 1/4" stainless steel rods to give them some support. Time will tell if this was a good idea.
It's the little things. Really. The nose cone is held on by three threaded bolts with their nuts held secure in the plates that hold the blades on. Imagine the problem with one of the nuts breaking free and spinning. How would you get to the blades and hub bolts if you could not remove the nose cone? The designers must have though of this as one of the plates had this small notch in it to mate with the nut, Then it was staked in place. One of the others had a weld and had almost broken free.
As I moved on to the slip ring assembly I thought I could avoid messing with that as the assembly has many parts and is a wiring nightmare. It was not to be as I inspected it I could tell that the ground wire was loose. Bummer. So I took is all apart and re-soldered in all new wires. Tricky but a good job done.
Then there was this groove cut around the main yaw shaft. This is right at the point where the three part flat thrust bearing sits. I could see no wear of marks on the thrust bearing parts and cannot figure out how this groove got hear. I greased her up and put it back together deciding to live with it for another 15 years.
This is getting to be quite a project. Hey I wounder what is under this little plug between the gear box and generator? Oh, Oh...
To be continued
After removing the blades and adding a second set of wheels to the gen stand/log mover I was able to wheel it into the shop.
With the nacelle removed I used the engine hoist to lift and separate the parts for inspection and repair of the unit.
The surprises just keep coming. Upon removal of a junction box cover this looks bad.
Looks like the wire nut did not do the job in this case and over time the connection got hot. Could have been a disaster for sure. The repair for this will be a split nut connector to give the connection a more solid connection.
Removed the base mount from the unit. This is where the mounting plate was cracked. I broke it off the rest of the way so I could grind a nice vee into the plates and increase the weld penetration. The small angle brace welds were a poor factory job with very little penetration and will be replaced with 1/4 inch thick material. A second 3/8 inch thick is being drilled and will be edge welded to the bottom of this plate for the repair. Same thing will have to be done for the blade mounting plate as the three holes where it attached to the generator hub are also showing some cracking.
Then it will be on to refinishing of the blades. Stay tuned.