From kls Sun Aug 4 16:44:54 1996 Newsgroups: sci.aeronautics.airliners Path: bounce-back From: Steven Foister Subject: Re: Jet Engine Containment Approved: kls@ohare.Chicago.COM Sender: kls@ohare.Chicago.COM References: Organization: GEC-Marconi Avionics Ltd. Date: 04 Aug 96 16:44:54 Message-ID: One of the certification tests required for all turbofans involves blowing a small charge near the root of a fan blade whilst the engine is in operation, causing it to detach. For the engine to pass the test, the blade needs to be fully contained. For the new large turbofans, this is an extremely demanding test. Kevlar is used as part of the containment because of its high tensile strength and low weight, and Rolls-Royce and Pratt&Witney have both used plenty of it on their engines to pass this test. GE however have a much heavier fan blade, which is more difficult to contain. Last I heard (January) their engine for the B777 had still not passed this test. They were trying to get a test which involved detonation half way up the blade (much less demanding) accepted instead. I believe that the GE90 engine is actually only operating at present on several such temporary waivers. Which would make me think twice about getting on a (GE-powered) BA 777. Anyway, I am sure that someone from GE will write in and refute me on that. Some of your neighbours at Iowa State are also likely to know more on this than I do. Finally, the reason for this test is the damage that a detached blade could do. But what about turboprops? Steve