Thrust of an engine - i.e. takeoff power (or cruise) - can also be determined by the fuel flow, provided you know the thrust specific fuel consumption of the engine. Some Air Florida 737 pilots (DCA accident) failed to look at their fuel flow, as their EPR PT2 gages (JT8D) were frozen by ice, and probably never knew of that fact.
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On 747 - JT9D-7Q engines, a FF of approximately 9000 KG would indicate a normal T/O thrust at sea level.
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