Critical Engine on the 747?
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Join Date: Dec 2002
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I really don't want to have to purchase a whole book to find out one answer. I have been using a lot of my old college books but none of them seem to have any 747 stuff in them.
Join Date: Aug 2001
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..unless of course you happened to be taxiing a Saudi 743 in Aug01 with just #2 & #3 alight...and knew nothing about the hydraulic system...in which case I would say that #1 would be critical.....but that's just being pedantic.
Join Date: Jun 2000
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Clowndown, the correct answer that they are looking for is that which is the into wind engine on the takeoff role. Simply explained as a xwind from the left will apply a yawing moment to the left with all engines running.....lose # 1 and the yawing moment is compounded. Conversely lose # 4 and the yawing moment is not as great.
Good luck
Good luck
Last edited by fire wall; 20th Jan 2003 at 09:21.
Join Date: Sep 1999
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To be absolutely correct:
It depends on whether the aircraft has positive or negative weathercock stability......
On the 4-engined jet I fly, which has POSITIVE Weathercock, the AFM states that the Critical Engine is the OUTER Engine on the UPWIND side.
It depends on whether the aircraft has positive or negative weathercock stability......
On the 4-engined jet I fly, which has POSITIVE Weathercock, the AFM states that the Critical Engine is the OUTER Engine on the UPWIND side.
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This topic (and quite a few similar) regularly arises on PPRuNe. Suggest that a search on "critical engine", "Vmcg", and "Vmc" (or "Vmca") will give you more than a coffee's worth of reading.
Certification things of interest are
(a) directional control characteristics
(b) loss of systems
while the typical interview question tends to relate to the crosswind consideration (which, basically, is ignored at certification). The thing to keep in mind here is that Vmcg is determined for nil wind (7 kt under the UK requirements) ... if you happen to be in a critical takeoff situation, with a decent crosswind ... then don't have an engine failure.
Certification things of interest are
(a) directional control characteristics
(b) loss of systems
while the typical interview question tends to relate to the crosswind consideration (which, basically, is ignored at certification). The thing to keep in mind here is that Vmcg is determined for nil wind (7 kt under the UK requirements) ... if you happen to be in a critical takeoff situation, with a decent crosswind ... then don't have an engine failure.
