Re: lock washers on LyCon

[Brent Regan]

Walter is correct in that the Lycoming assembly requires both split and toothed lock washers. They also require coarse threaded fasteners. However, just because it has been done that way since magnetos were made out of flint doesn't make it correct in modern times, just ask Copernicus. Lock washers keep a loose bolt from falling off, but, by the time a fastener is loose enough for a lock washer's spring action to come into play it is already too late for the clamped interface.

I have a shelf full of aerospace fastener catalogs, nary a lock washer to be found. I have a bucket full of sweepings (dropped fasteners, "If it hits the floor it is used no more.") from the Boeing plant. No lock washers there either. On my TIO540 engine I replaced the case half through bolts with fine thread MS hardware and no lock washers. The few stock fasteners (studs I couldn't replace) require retorque regularly as Walter recommends but the replacement fasteners do not.

It pains me to think that Walter was insulted by my comments. To the contrary, I am confident that his leak free experiences are testimony to his skill as a mechanic and are no way attributable to the lock washer.

Regards
Brent Regan