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Originally Posted June 2014

These are photos showing a crack we found on a LH upper tailboom attach fitting. The crack was initiated at the Hy-Lok pin bore and was on both sides of the bore. There was some corrosion pitting on the back side of the fitting at this hole and this may have been the origin of the crack. The helicopter was used for touchdown autorotation training within the last 100 hours and this may have contributed to the stresses that caused the crack. It was found at a routine 100 hour inspection (not on a preflight). This is the most critical of the 4 fittings.

I’m sending this out knowing that you all know this is a critical area to look at but at the same time recognizing that as public use operators our inspection programs are all different. I am pretty sure this crack happened over roughly a 100 hour interval. There was no sudden bang as there have been with some fitting failures and no pilots saw this on preflight. I don’t fault them for that either. In my book our inspection program worked the way it should. Before the paint removal it was visible without magnification but could be easily missed if you were not specifically looking at this fitting for this sort of defect. I know I’m preaching to the choir and I say this only because of things I’ve missed over the years; we may have to remind ourselves that we look at aircraft to find bad stuff, not so they can go fly.

Jon Robbins

Aviation Officer II (M)


Aviation Management Unit

5500 Price Avenue

McClellan, CA 95652

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