To specify minimum requirements for Fuel Flowmeters for use primarily in reciprocating engine powered civil transport aircraft, the operation of which may subject the instruments to the environmental conditions specified in Section 3.3. This Aeronautical Standard covers two basic types of instruments, or combinations thereof, intended for use in indicating fuel consumption of aircraft engines as follows: TYPE I - Measure rate of flow of fuel used. TYPE II - Totalize amount of fuel consumed or remaining.