PPRuNe Forums - View Single Post - Rotation side of jet engine? / critical engine?
Old 7th Nov 2012, 13:18
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enicalyth
 
Join Date: Jul 2004
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Not so... Hetfield is incorrect

Historically US engines rotated one way and European ones the other. So it all depends. For that reason 5 minutes before crossing from one hemisphere to the other first one engine on a twin is shut down and restarted spinning the other way and then the next. Which to shut down first depends on Airbus or Boeing. The RAF flew TriStars and had to land at Ascension before going on to Mount Pleasant because of this. It was known as going tech at Asi and aircraft always went tech at ASI. Great care had to be taken to offset Coriolis force on Triples eg Rollers go one way and PW the other. It was not unknown for the MD-11s to get confused and many handling mishaps were due to this cause. Funnily enough DC10s managed to get it sorted but then they had real flight engineers. MD eventually scrapped the fleet because of the risk of memory items being recalled incorrectly. With Quads it is possible to have them going both ways so none of this applies to A380/A340/B747. Only twins on EROPS or Engines Run Opposite Sides need this rule these days. Contra-rotating props were especially designed to cross the equator and the only worry was if they carried enough oil in the first place.
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