Date: 05 Jan 97 03:22:36 From: email@example.com ( 0 Falke_Charlie phone dist ) References: 1
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> This has been a very interesting discussion, but I'm wondering > if it isn't focusing on the wrong things. If I recall correctly ... > and improving containment of engine failures. Trying to > further mitigate the already-improbable case of multiple > independent engine failures doesn't look like a winning strategy. Interesting points and questions. In airplanes and engines that are designed for ETOPS, considerable care is taken for common mode and fraternal damage. The situation in the DC-10 where all three hydraulic system's lines were right next to each other wouldn't cut it for ETOPS. As an example, the electrical cables that carry the throttle position signal in an ETOPS twin typically run well apart from each other for each engine, and for each channel of the dual channel electronic engine control. A typical route on one side would be that one channel will run up the leading edge and the left side of the fuselage, and the other up the trailing edge, and around over the cabin and up the right side. We even have to design the fuel and oil plumbing so that if the right engine throws a fan blade under the fuselage at the left engine, it won't cut any of the lines. (This means the lines either go on the left side of the engine, or higher up.) This is, of course, after we have succesfully demonstrated explosively releasing a fan blade and containing it. Boeing runs "blade out" tests as well, which also assume that we've failed ours, and blow a simulated fan blade through a fully pressurized fuselage, and show that the tear doesn't propagate. Containing disks (much heavier than blades) doesn't seem practical. The approach for these is to run pacer endurance engines to put more cycles on a test engine than anybody else's has, and establish a safe life. -- Charlie Falke Pratt & Whitney System Test Team Leader C/O Boeing Comm AP grp.