4-20 P/N 13772-003
Section 4 Cirrus Design
Normal Procedures SR22T
Cruise Climb: Lean of Peak Technique
1. Power Lever .............................................. REDUCE to 30.5 in.Hg
2. Mixture ................................................ LEAN to cyan target or less
3. Minimum Airspeed ...........................................................120 KIAS
4. Fuel Pump.......................................................................... BOOST
5. Oxygen.................................................................. AS REQUIRED
a. Oxygen Masks/Cannulas.................................................. DON
b. Oxygen System .................................................................. ON
c. Flow Rate .........................ADJUST for planned cruise altitude
d. Flowmeters and Quantity......................................... MONITOR
6. Cylinder Head Temperatures ......................................... MONITOR
Amplification
Cruise climb with the mixture lever set to a lean mixture setting (LOP)
is acceptable provided CHTs remain under 420ºF. This climb
procedure may not be possible in hot weather, but in moderate
temperature conditions, LOP cruise climbs provide extended range
and better fuel economy. Depending on aircraft weight and OAT, LOP
cruise climbs will result in 600 to 700 FPM rates of climb at 130-140
KIAS.
Target fuel flow is calculated to provide the approximate Lean of Peak /
“Best Economy” fuel-to-air ratio. Dependant on OAT and airspeed, this
setting may not guarantee cylinder head temperatures below 420°F. If
any CHT’s are greater than 420°F, lean the mixture to maintain
cylinders below 420°F. If cylinder head temperatures consistently
exceed 420°F, climbs should be made at full rich mixture as described
in the Climb Checklist.
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