Re: Broken Skytech pinion tooth (Q200)
Kevin Fortin <kfortin@...>
Guys,
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I forgot to include in my previous email that a major deflection of the pinion shaft was detectable because the pinion was pushed far enough off center to put a gouge in an aluminum "shroud" that wraps around the "open" side of the pinion (the shroud is part of the starter casting). Skytech knew immediately what I was talking about when I mentioned this. This deflection is what made me believe that the gears are off center to begin with. I know from experience that improper centerline distances, on the plus side, increase gear separation forces dramatically. I don't think there is anything intrinsically wrong with the pinion itself. Apparently it is supplied by Hitachi and is used for other starters in the aircraft industry. Kevin
-----Original Message-----
From: britmcman@aol.com [mailto:britmcman@aol.com] Sent: Tuesday, February 22, 2005 9:02 PM To: Q-LIST@yahoogroups.com Subject: Re: [Q-LIST] Broken Skytech pinion tooth (Q200) Hello All: There is a lot of available science out there regarding failure analysis. The broken gears that so many of you seem to have produced should be looked at by a metallurgical analytical lab. In order to solve this problem there ought to be someone at Skytec doing all of this anyway. When something isn't right, there is a reason. Consider defective metals, castings, forgings, heat treatments, case hardenings, etc. A look at the fracture with an electron microscope may reveal the real reason that gear tooth broke off. I would insist that the manufacturer conduct a thorough root cause and corrective action investigation. They should insist on doing it if they want to stay in business. The starter's design and materials should be robust enough to survive routine occurrences such as kickback. Phil Lankford N870BM B&C Starter [Non-text portions of this message have been removed] Quickie Builders Association WEB site http://www.quickiebuilders.org Yahoo! Groups Links
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