Re: A 777 with four engines.

Date:         18 Aug 98 01:04:43 
From:         darren@daz-technology.demon.co.uk (Darren Rhodes)
Organization: Daz Technology
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On 06 Aug 98 11:26:36 , faurecm@halcyon.com (C. Marin Faure) wrote:
>This is not true of turbofan engines, as long as temperature and N-speeds
>are not exceeded.  If you look at the graph representing the chances of
>failure vs. power output of piston engines and turbofan engines, the
>failure rate line climbs steeply with power output from a piston engine,
>but remains relatively flat with turbofan engines.  In other words, a
>turbofan doesn't care what power setting you use so long as its
>temperature and rotational limits are not exceeded.  Pushing the power up
>on the remaining engine of a twin-engine jetliner does not add to the risk
>of engine failure as it would if you were flying a twin-engine piston
>airplane.

I have heard of a 747-400 operator that has 9 out of 10 engine
shutdowns at high power, i.e. during takeoff.

Temperature exceedance is one thing, but reduced margin at high power
on high time turbine blades is an issue.

--
Mr. Darren P. Rhodes, BEng. (Hons)        | Aircraft Performance
Email: darren@daz-technology.demon.co.uk  | Analysis & Noise
Web:   www.daz-technology.demon.co.uk     | Specialist