Kevin, An additional note: If the thread is in a soft metal, like your aluminum Lyc cases it will be corse (unc) thread. the reason is that the thicker thread root will resist tear-out better in aluminum. Steel has a much higher tensile strength and usually is strongest in a fine (unf) thread. My personal comment on lock washers is that they are nearly worthless. Apparently Lycoming agrees! A properly torqued bolt won't come loose. Be sure to get a good quality torque wrench and USE IT. I recomend a foot pound wrench approx 15-100ft pounds, and an inch pound wrench from 10 or 15-200in pounds. Split washers make an unstable base for your bolt/nut and cuts up your part or fastener. Buy stock in Locktite it works! Use safety wire it works! A GREAT book is Fasteners and Plumbing by Carrol Smith. This book has a ton of great infomation in it. I am on my third copy they tend to walk off.
Bill Jepson


-----Original Message-----
From: wrjjrs@aol.com
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Tue, 18 Nov 2008 1:31 pm
Subject: [FlyRotary] Re: bolt depth