Date: 16 Oct 97 00:44:12
From: "D Eunson" <djeunson@netcomuk.co.uk>
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H Andrew Chuang <Chuanga@cris.com> wrote in article <airliners.1997.2452@ohare.Chicago.COM>...
> Malcolm, I think you know that the Sioux City accident was not due to
> a fan-blade failure. It was due to a rotor-disk failure. All engines
> do have to go through a fan-blade-failure test just like they have to
> go through birdstrike tests (but not a rotor-disk-failure test). In
> most cases, a fan-blade failure should not cause a catastrophic failure
> of the engine.
You seem to use the word catastrophic somewhat loosely. You are quite
right that tests are carried out to demonstrate that a fan blade can be
released and contained without hazarding the aircraft by releasing high
energy debris. As you say, this is not catastrophic. Tests are also
carried out on both rigs and engines to demonstrate the engines ability to
withstand birdstrike of a number of 1.5 pound birds and (rig test, fan
only) one 8 pound bird (well a block of gelatin). after the engine test,
the engine must be able to continue running for a period of time with no
intervention from the driver (which of course the Trent 800 can do). This
then is not catastrophic. While it is true that the Wide chord Fan will
centrifuge a high proportion of debris down the bypass, anything impacting
near the spinner does stand a chance of being ingested by the core (bear in
mind that one of the 1.5 pound birds is fired at the spinner). If a bird /
foreign object of sufficient size were ingested by the core, then damage
could result to the core compressor blades and it would not be
unreasonable to assume that there is a risk of failing a damaged compressor
blade at some time in the future if the engine continues to run on in
service. As with the above situations, there is nothing catastrophic, nor
any risk of release of high energy debris associated with a core compressor
blade failure (the casings being designed for containment). Many engines
have run on with sections of compressor blade missing, the damage only
being found on borescope inspection.
Essentially, the T800 failure was definitely not catastrophic!
By the way, who says Cathay hate twins?
