Fact - There is
no critical engine in a jet aircraft -
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Many of you have established that fact here above. And obviously, the outboard engines in a 4-engine aircraft are the two "critical engines" as compared to the inboard engines. It does not matter if nš 1 or nš 4 fails, the resulting VmcG will be equal. No need to say, same applies to 2-engine aircraft, the resulting VmcG are equal with the L or R engine failed.
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This is for FAA (FAR 25) certification.
However, the British CAA accounts for crosswind effect on VMCG. In the case of 747-200/300s as an example, in the minimum V1 speeds (restricted by VmcG), speeds in the FOM/QRH are different in airplanes certificated as per FAA and CAA. Those of you who operate such 747s, if you have the original Boeing FOM manuals, if they are marked at the bottom of pages by "FAA", or "CAA", next to the page revision date, it will indicate to you which certification was used (among other info) for the speed tables, and the speed tables are different. VmcG/V1 speeds are higher for CAA certification.
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In the simulator, when I train pilots, I can demonstrate VmcG/V1 engine failures that are controlable at speeds as low as about 115 KIAS, or uncontrolable at speeds as high as 135 KIAS, this based on which engine power, CG position and crosswind factors...
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Now again - nose wheel steering...
How do I say it again, in English, Spanish or Guarani - it is
WORTHLESS -
If you think that your nose wheel steering will assist you, you are having a dream.
Read the following...
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Background -
In July 2001, LV-MLP (a 747-287B) sustained damage by veering off the runway during takeoff at Buenos Aires EZE airport. The weather was partially obscured by light drizzle and fog, wind calm. The captain stated that the takeoff roll began normally with only minor corrections, with the tiller, to maintain runway centerline. Prior to receiving the "80-knots" call, the captain felt the airplane moving to the right. He applied left rudder and left nosewheel steering
without any effect on the path of the airplane. Prior to departing the runway, and with right drift increasing, the captain stated that he applied full left rudder and nosewheel steering. The right wing gear damaged a few runway lights, and departed the runway concrete area. The captain then retarded the power on nš 1 engine to turn the nose of the aircraft towards the centerline, then, retarded all thrust levers to idle and the T/O autobrakes stopped the aircraft.
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The probable cause of the incident was the captain's failure to reject the takeoff in a timely manner when excessive nosewheel inputs resulted in a loss of directional control of the aircraft.
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We have concluded that the procedure to "guard the tiller" during the takeoff roll to 80 knots increased the likelihood for overcontrol of the nosewheel, and that we should eliminate the procedure. From then on, our procedure changed to instruct the captain not to guard the tiller, and place his hand on the wheel, after alignment for takeoff on the runway. I was instructed by the chief pilot to effect the new procedure to all types (747, 737, MD-80 and A-310s), effective immediately. There were no further problems since the procedure changed.
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Further, "elevator down" to "increase nosewheel effectiveness" is worthless. It is obviously worthless at low speeds, worse, it does
increase aerodynamic drag at higher speeds. Directional control should rely only on aerodynamic forces, once the aircraft starts rolling for takeoff. Elevators are kept in a "neutral/faired" position.
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Boeing sent us a bulletin confirming our change of procedures without objections.
Be aware that with PanAm, the "rudder pedal-nosewheel steering" linkage in the 747 was disconnected and removed even from 747 airplanes we acquired from other airlines which were so equipped. And pilots did not "guard the tiller" during takeoff roll to "80 knots".
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Happy contrails
P.S. For those of you who play with "engine out ferries" qualification, like I have to do occasionally, with the 747-200s, the "VmcG-2 is 160 - VmcA-2 is 155 KIAS" with Flaps 10 and JT9D-7Q power, at 3 engine-ferry weights.