(a)(1) The engine shall be tested in each of the following engine operating modes which simulate aircraft operation to determine its mass emission rates. The actual power setting, when corrected to standard day conditions, should correspond to the following percentages of rated output. Analytical correction for variations from reference day conditions and minor variations in actual power setting should be specified and/or approved by the Administrator:

------------------------------------------------------------------------
                                                     Class
                Mode                 -----------------------------------
                                          TP      TF, T3, T8      TSS
------------------------------------------------------------------------
Taxi/idle...........................         (*)         (*)         (*)
Takeoff.............................         100         100         100
Climbout............................          90          85          65
Descent.............................          NA          NA          15
Approach............................          30          30          34
------------------------------------------------------------------------
*See paragraph (a) of this section.

(2) The taxi/idle operating modes shall be carried out at a power setting of 7% rated thrust unless the Administrator determines that the unique characteristics of an engine model undergoing certification testing at 7% would result in substantially different HC and CO emissions than if the engine model were tested at the manufacturers recommended idle power setting. In such cases the Administrator shall specify an alternative test condition.

(3) The times in mode (TIM) shall be as specified below:

------------------------------------------------------------------------
                                                     Class
                Mode                 -----------------------------------
                                          TP      TF, T3, T8      TSS
------------------------------------------------------------------------
Taxi/idle...........................   26.0 Min.   26.0 Min.   26.0 Min.
Takeoff.............................         0.5         0.7         1.2
Climbout............................         2.5         2.2         2.0
Descent.............................         N/A         N/A         1.2
Approach............................         4.5         4.0         2.3
------------------------------------------------------------------------

(b) Emissions testing shall be conducted on warmed-up engines which have achieved a steady operating temperature.