We discovered a potential safety issue and wanted to share this so others become
aware of the situation and can inspect their aircraft.
We are in the process of our annual condition inspection on our mono wheel.
This
year is extensive since motor mounts and bungee cord need replaced. After
being alerted by John Wigney of possible cracks in the lower tubes of the LG
frame,
we inspected and discovered our frame is cracked like his. The cracks are
very difficult to find as they are somewhat hidden by the firewall and behind
the vertical tubes of the frame. Using Johns photos, a strong light, and
magnifying
glass, we were able to see a crack in the starboard tube. A photo with
our iPad actually gave the best indication of a crack. A dye penetrant test
confirmed the crack. The crack in the port tube wasnt evident until the powder
coat was removed. The attached document has good photos of Johns cracks.
We removed the frame and had it repaired by an experienced A&P (FAA mechanic)
using
techniques called out in AC 43-13. We reamed out the tubes and machined
a tube to be a tight fit similar to Mod 72 for the upper tubes except the insert
is the full length of the tube. The insert is welded to the original tube
with rosette welds, and the cracks were stop drilled prior to welding. One bolt
hole was elongated so we changed it to AN4.
A side note, when we started to remove the LG frame, we found that some of the
mounting bolts were no longer tight. When doing your inspection, we suggest you
check these nuts and if any are at all loose, inspect very carefully for cracks.
Our mono wheel kit was purchased April 2000, kit A185 and has 975 hours.
Jim & Heather
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=484894#484894
Attachments:
http://forums.matronics.com//files/181001a_photo_summary_of_landing_gear_frame_cracks_131.pdf
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