Metal choices (Was:Tie Rod Fracture Input)

[PhantomOfO@domain.elided]

Hello all, 
    Just to add my two cents to this from a slightly different point of 
view.....Besides honking around in an 86 Alfa Spider Quad, I also fly.  
Several years ago, under force of law, I had to replace my oil pump impeller 
gears.  This is no simple task, since it is  housed in what is called the 
accessory case on the back of the engine.  It was also financially a poor 
move since the engine had only a few hundred hours more until its recommended 
overhaul.  Guess why all the fuss?  The nice engineers at Lycoming, had 
speced a sintered metal be used to make the gear.  (Hope I am spelling that 
right.)  For those of you who may not know, this is apparently to metal what 
pressboard is to wood.  And this is what they used to drive the oil pump on 
the only engine used in an aircraft?  I am betting the engineer who spec'd 
this saved a few bucks on each unit....Cost me about a thousand.  
	Thought everybody might find this interesting.
Best,
Ralph Fox  

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