Section 7
Columbia 400 (LC41-550FG)
Description of the Airplane and Systems
Initial Issue of Manual: November 10, 2004
RC050002
Latest Revision Level/Date: A/12-01-2004
7-109
1. Press the “Lean Assist” button and slowly lean the mixture.
2. The MFD will annunciate “Looking for Peak” on the engine page.
3. When the MFD has detected a peak in the TIT, it will annunciate “Best Power – Richen to -
50°” and the TIT bar graph will turn cyan, showing a differential temperature from the peak.
4. Move the mixture back towards rich until the TIT bar graph shows a differential temperature
from the peak of -50°. When this point is neared, the MFD will annunciate “Best Power”.
5. After the desired setting has been achieved, press the “Normalize” or “Absolute” buttons to
exit the Lean Assist function. The lean state (in this case “Power”) will continue to be
provided in the data block on the map page.
Figure 7 - 37
After following the instructions above, the mixture setting is just below peak TIT on the rich
side. If the mixture is moved too far towards rich, the MFD will annunciate “Rich of Best
Power” and if moved too far lean, “Too Lean, Richen Mixture”. Also, as a precaution, the Lean
Assist algorithm will not allow leaning past a TIT of 1700°F. If there is no peak detected before
reaching 1700°F, the system uses 1700°F as the peak. Therefore, if this temperature is reached
during leaning, the MFD will instruct the pilot to richen to -50° from that point.
If the pilot enriches the mixture before the system shows peak detected, the system will interpret
the highest TIT before the drop in TIT as a false peak. The “Absolute” button should be used to
exit the “lean assist” function and if required, the leaning process can be started again from full
rich mixture.
CAUTION
When using the Lean Assist function, it may be possible to temporarily enter the
yellow range of the TIT gauge, but once properly leaned, the temperature is in the
normal operating range.
