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From: RWolf99@aol.com
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Date: Mon, 21 Feb 2000 19:16:50 EST
Subject: Fatigue Life of Engines
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>>

In a message dated 2/20/0 9:46:07 PM, you wrote:

<<If the number of stress cycles is the dominant
factor in determining fatigue life, why do Top
Fuel Dragsters have a TBO in the neighborhood of
three minutes?>>

I don't claim to be an expert in this area.  I don't have a clue about the 
answer to this interesting question.  My prior comments were directed to the 
notion that long-term damage would be forstalled if engines are operated at 
low power settings on takeoff.  If they were not well expressed, I apologize 
to anyone I've offended.

My comments were directed at the notion that partial-power takeoffs were 
gentler on the engine, and thus preferable.  My thoughts are that safety is 
enhanced by getting the takeoff finished quicker and gaining safe altitude 
fast, suggesting that maximum available power should be used for takeoff.  
The takeoff is a small portion of an average flight, and the 
engine-life-prolonging benefits of reduced power operation probably ought to 
be realized in cruise, not on takeoff.

Concerning full-power runups, I do mine at 1700 rpm, but once on the runway I 
throttle up to 100%, verify the correct RPM is attained, and that the engine 
gauges are in the green and not changing.  So maybe this three-second 
full-power check attains the same goal as the full-power runup.  I agree, 
it's good to be sure you can get 100% power before you start rolling...

Happy flying.

- Rob
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