Lean Assist Mode
During the leaning procedure, the engine is not leaned beyond the engine or aircraft limitations and that the engine continues to operate smoothly after setting the mixture. Should any engine roughness occur during leaning, consult the aircraft POH or AFM for appropriate leaning of the engine.
The Lean Assist functions are calculated using the relationship between fuel flow and EGTs (or TIT). If a false EGT peak is observed and does not automatically reset, disable the Lean Assist function, reset throttle and mixture controls, and reattempt.
It is recommended to set the aircraft power settings for cruise flight and to let the engine temperatures settle prior to beginning the lean find process.
The pilot should follow the engine manufacturer’s recommended leaning procedures as described in the Pilot’s Operating Handbook (POH).
When interfaced with a fuel flow sensor, the AXIS™ EIS provides two different lean assist methods, rich of peak or lean of peak.
Lean assist mode is initiated by navigating to the 'Engine' Application on the MFW and accessing the 'EIS Menu' using the MENU Softkey and then turning the inner knob to activate Lean mode. As the mixture is leaned, Lean mode automatically detects the first and last EGT (or TIT if installed and configured) peak and indicates peak by using a bar above the EGT indicator for the cylinder.
- Rich of Peak (ROP) － Detects and indicates the first engine cylinder to peak during the leaning process. Once the first peak in EGT (or TIT) is detected, the temperature differential from the recorded maximum EGT (or TIT) of the first cylinder to peak is displayed and the pilot can enrich the mixture to reach the proper operating temperature from peak using that value.
- Lean of Peak (LOP) － Detects and indicates the last engine cylinder to peak during the leaning process. Once the last cylinder peak EGT (or TIT) is detected, the system will display the temperature differential from the recorded maximum EGT (or TIT) of the last cylinder to peak and the pilot can continue to lean the mixture to reach the proper operating temperature from peak using that value.
A dual-pointer gauge is displayed when exactly two cylinders of EGT are configured and appears on the Engine Application the same way the TIT configured image appears below. Each cylinder has its own peak temperature triangle.
The following gauge is displayed when TIT is configured instead of EGT.
A ‘+’ (∆EGT) value indicates the current temperature is greater than the previously detected peak.
If a fuel flow sensor is configured, the fuel flow value detected as the first cylinder peaks is saved. The fuel flow corresponding to peak EGT (or TIT) is drawn on the fuel flow gauge as a hollow cyan pointer. This can be used to determine if you are on the rich side of peak (ROP) or the lean side of peak (LOP). Rich of Peak (ROP) if the fuel flow pointer is greater than the hollow cyan triangle, or Lean of Peak (LOP) if the fuel flow pointer is less than the hollow cyan triangle.
The EIS displays the cylinder whose temperature is currently closest to its own peak value (when Lean Assist Mode is active) as a white pointer with the cylinder number. The peak temperature is depicted by a hollow cyan pointer, and the temperature deviation from peak (∆EGT or ∆TIT) is displayed in place of the normal temperature number in cyan text.