Date: 16 Oct 97 00:44:12 From: "D Eunson" <email@example.com> Organization: N/A References: 1 2 3 4 5 Followups: 1 2
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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?