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SERVICE BULLETIN 16-05-23

730 hours all off grass no cracks . No wheel pants. Brad Stiefvater
Salem SD

Question - Why no wheel pants when flying off grass? I fly off grass and like the pants to keep bottom of plane cleaner. Grass doesn't seem to accumulate in the pants however I'm constantly vigilant.
 
I fly year round it avoids any problems with snow/ice. in these South Dakota winters.


Brad Stiefvater
Salem SD
 
To check ,inspect for cracks in my past we were required to remove the paint as the paint will cover up cracks. Any thoughts?
 
170 hours, mostly hard surface, no cracks.
Incidentally, that is a pretty hefty fork. Surprised to see so many failures
I would think that a crack would show with or without paint
 
How very kind of Van's to issue the SB while I already have the plane apart and up on stands for its condition inspection. 240-some hours, no cracks. And yes, it does seem like a pretty hefty part.
 
Original and Replacement Nose Fork N712BK

I posted a photo of my nose wheel fork failure on 4/26/16 on the Nose Wheel Crack thread started by Andre Mendonca. The welds on the nose forks are significantly different. The weld bead on the replacement nose fork is much wider with a larger heat affected area radiating out from the edge of the weld indicating good weld penetration.

The original nose fork fractured completely as I was removing the tire. This cross section shows that there is no penetration in most of the weld. There is a pretty little fillet weld sitting on top of the ?joined? pieces of metal to quote my structures guru.


Bob Kibby (N712BK, 295 hrs)
 
Bigger weld bead doesn't necessarily mean deeper penetration...... .........

As posted in a previous thread about the nose fork, supplemental testing was done on the nose fork at the request of the FAA after a botched landing accident.

A number of different forks were tested (big weld bead, small weld bead, etc.) and all failed under static load at very near the same load value, and well beyond the required load. The FAA was fully satisfied with the results of the testing.


This thread is about cracks that begin at the edge of the fork web, that if allowed to propagate, will likely result in the nose fork disassembling itself.
 
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Nose fork inspection

I inspected my nose fork last night, 47 hours, all on pavement. No cracks found. I do treat my nose wheel with the utmost respect, as instructed by Mike Seager and John Albury.
 
Last annual in March: 438 hours and no cracks. If I find any in the future I'll crank up my under utilized TIG welder and do a weld repair.
 
Just checked at 106.2 Hobbs. In perfect condition. Any suggestions for appropriate log entry, this will be my first SB since taking possession of the plane. Thanks.
 
So far it looks like there are not very many cracks out there. Not sure how many it takes to justify a recurring SB. Hope we can get a count and cause at the end, but I guess that we are stuck with the SB. Oh well.............
 
Nose fork collapse

Bob,

Was your fork replaced at "no charge?" Mine collapsed 200' after landing roll-out this past weekend. My -12 also has the old style fork.
 
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