Effective Date: 15 June 98
Engine Operation
Engine Response
The purpose of this analysis is to evaluate engine operating characteristics during transient operation. Of particular interest are acceleration and deceleration rates and any tendency towards compressor stall or flameout to a hazardous degree, during normal and emergency operation of the engine.
Data recorded on tape will be presented and analyzed in the form of time history plots of the following parameters:
o Altitude
o Airspeed
o Total air temperature
o Engine speed (Nl, N2, N3)
o Turbine gas temperature (TGT)
o EPR
o Fuel flow
o HP compressor delivery pressure (PS4)
o Engine power lever position
Engine acceleration and deceleration rates will be determined from a plot of the rotor speeds using the time at initial throttle movement as zero reference. The thrust available at any given time during the transient can be evaluated from EPR. The plots of turbine gas temperature are used to show any over- temperature tendency during acceleration.
Any tendency toward surging would be seen as instability in the HP compressor delivery pressure (PS4). The fuel flow rate data can be useful in establishing proper functioning of the engine fuel control, since slow acceleration, high TGT and sometimes compressor surge can be caused by improper operation of the fuel control.
Thrust Reverser and Hot Stream Spoiler Gas Impingement
Evaluation
The purpose of this analysis is to evaluate the degree and effect of exhaust gas impingement on airplane structure while operating the engines in the reverse thrust configuration. Following a reverse thrust landing, the skin temperatures of the various surfaces will be manually recorded from observation of the temperature sensitive material; colored photographs will be taken of the areas before and after the run. The results will be presented as shown in Figures 1 and 2. The skin temperature data will be extrapolated to hot day conditions using a 1:1 extrapolation and compared with the maximum allowable values.