40 CFR 90.417 - Fuel flow measurement specifications.
(a) Fuel flow measurement is required only for raw testing. Fuel flow is allowed for dilute testing.
(b) The fuel flow measurement instrument must have a minimum accuracy of one percent of full-scale flow rate for each measurement range used. An exception is allowed for the idle mode. For this mode, the minimum accuracy is ±five percent of full-scale flow rate for the measurement range used. The controlling parameters are the elapsed time measurement of the event and the weight or volume measurement. You may apply the accuracy specifications of 40 CFR part 1065, subpart C, instead of those in this paragraph (b).