On a 2009 OBX trip, my friend Andy McKinney and I spent some time giving my extensions a close examination.
Now mind you, I think I take reasonably good care of my stuff. But I had never taken apart my extensions to examine the tendons.
At the time, I was using the Chinook euro-pin tendon design. I have three of them, and they are all in their 3rd year. Overall the piece is bullet proof. Unfortunately you cant see the part that fails until its too late (2 Miles off shore in an offshore wind). the only part that tends to fail on you is the tendon itself. But the part of the tendon that fails is concealed just below the stainless steel.
Click on these pictures to get the full screen view
The hole you see thru the tendon is where the crew passes thru to attach to the stainless steel pin. This is where the tendon fails. I was shocked to see what i had been sailing on. That crack you see running out from the screw is not normal, and it was only a matter of time before this one failed completely. I was literally one solid crash or dues paying moment away from being in a potentially bad situation. Phew, can't tell you how blessed i felt to have examined mine. Thanks Andy!
In fact, ALL THREE of my tendons where compromised! Fortunately, you can get a replacement tendon for about $10.
Take advantage of those non-windy moments. More specifically, I highly suggest you take a close look at your universals, and if you use the Chinook tendon, take it apart and examine it closely on a regular basis.