Re: 777 P&W Failure

From: (Andrew Chuang)
Organization: International Internet Association.
Date:         20 Nov 94 01:59:02 
References:   1 2 3 4
Followups:    1
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RNA (rna@leland.Stanford.EDU) wrote:

: Nor at GE, I have read that they too are having setbacks with the GE90
: certification.  Something to do with the new wide-chord fans in the
: engine.  Can someone in the know please elaborate?

GE proposed a controversial modification for the blade-out containment
test.  GE claimed the conventional test should not be applicable for their
unique carbon-composite fan blades.  (P&W and R-R use hollowed-titanium
blades.)  Both P&W and R-R objected to the modification, but FAA agreed
with GE.  Basically, GE proposed to break off the blade in the flow
passage rather than at the root during the test.  If one is interested in
more details, please refer to Aviation Week.  With this modification, GE
won't need to further strengthen the casing.  Otherwise, the engine
may become less competitive due of additional casing weight.

(One of the most recent fan blade failure that I can recall is about a year
ago.  A relatively new [two-year old?] Cathay Pacific B747-400 out of Los
Angeles experienced a fan blade failure in a RB211-524H.  The failure was
contained and the plane safely returned to LAX.  R-R could not identify
the cause for the failure.)

Back to the GE90, the two-week delay of the GE90 certification was not due
to the above test.  It was mostly because of a test engine failure occurred
last month which was reported in details by Aviation Week (who else!).  In
addition to the fan-containment test, the GE90 still need to pass the 8-lb
bird-strike test before the certification.

Some of the significant dates for the three engines are listed below,
(from my rusty memory, so some dates may not be correct):

          Engine cert.  First 777 flight   A/C cert.     First revenue flight
PW4084     Apr 1994       June 1994        May 1995       June 1995 (UA)
GE90       Dec 1994       Dec  1994        Aug 1995       Sept 1995 (BA)
Trent800   Jan 1995*      June 1995 ?      Dec 1995 ?     Jan  1996?(Thai)

* the Trent 800 was originally scheduled to be certified in March of 95.

P.S.  I once read that Boeing insisted on R-R having their Trent 800 flown
      on a flying testbed before it is flown on a B777.  I have yet to
      read about R-R's plan, does anyone know?  (The PW4084 flew on a B747
      in Oct, 93, and the GE90 flew on another B747 in Nov, 93.)

         |  H Andrew Chuang  |