Re: 30-year-old technology

Date:         20 Mar 97 02:34:54 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
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>Absolutely right.  The GE90 is a heap of s**t compared to the Trent...BA
>has had to revoke ETOPS clearance for all 777-100 a/c as the engines are

Presumably you're referring to the fact that BA has temporarily
stopped using their 777-200 IGWs (there is no 777-100) across the
Atlantic.  The problem occurred only on the GE90-90B engine, which
BA refers to as a GE90-85B since they don't need the higher thrust
and operate it at a derated thrust level.  This engine is used on
the 777-200 IGW.  The GE90-76B, which does not have the problem
(contaminated oil, traced to bearings in the drive gearbox for the
variable speed constant frequency (VCSF) generator), is used on BA's
original five A-market 777-200s, which presumably have gone back to
flying the trans-Atlantic routes (is LHR-BOS the only one BA flies
with 777s?) as they were doing before the first IGW arrived last
month.  The IGWs, which have still been flying albeit on shorter
routes, are expected to be back on the route this week, with lower-
rated VCSF drives from the GE90-76B engines.

Compare this to the PW4084 -- in the first few weeks of service with
United, at least one entire engine was replaced.  Might have been two
but I can't remember for sure.

Sure, the GE90 has had problems.  That's to be expected from any new
engine design.  Look back at the JT9D when it was introduced on the
747 -- three round-trips between New York and London and you'd throw
them out.  Now *those* were crappy engines!  The early RB.211s were
not much better, either, not even counting all the problems before
they went into service.

Oh yes, neither BA nor any other airline has the authority to grant
ETOPS clearance to an airframe/engine combination, nor do they have
the authority to revoke such clearance.  BA merely chose not to
operate their 777-200 IGWs on ETOPS flights until the engine problem
was fixed.

Karl Swartz	|Home
Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills