Cessna 172SPHUSR05 Pilot Operating Handbook page 125

CESSNA
MODEL 1 72S
750/ 0
KTAS NMPG KTAS NMPG KTAS
ALTITU D E
Sea Level 1 14 1 1 .2
4000 feet 1 1 9 1 1 .7
8000 feet 1 24 1 2.2
Figure 4-3. CrUise Performance Table
L EANING WITH A N EGT I N DI CATOR
temperature (EGT) indicator i s used to lean the fuel-air mi x ture fo 75%
At or below
best performance or economy. The Crui s e Performance charts in
Secti o n 5 are based on the EGT to adjust the mi x ture to
R ecommen e ean per Igure - d d L
MIXT U R E D ESCR I PTION
RECOMMENDED LEAN
(Pilot' s Operati n g Handbook )
BEST ECONOMY
Use the mi x ture control vernier adjustment (rotate the knob CCW
to lean the mi x ture) to
mi x ture, while moni t oring the EGT indi c ator. As the EGT indicati o n
begins to increase, continue to
indication decrease i s just detectable. Reverse the adjustment
in the ri c h directi o n until an EGT i n di c ation decrease i s
agai n just detectable, then set the EGT index pointer to match the
slowly
peak indi c ati o n. The mi x ture may be leaned sli g htl y to return to
peak EGT or may be further ri c hened to Recommended Lean
mixture as desired.
posi t i o n will require that peak EGT be redetermined and the desired
lean of peak EGT is prohibited.
mixture be reset. Under some condi t i o ns, engine roughness may
occur at peak EGT. In thi s case, operate at Recommended Lean
mi x ture.
As noted in Fi g ure 4-4, operati o n at peak EGT provides the best
fuel economy. Operati o n at peak EGT resul t s i n approximatel y 4%
greater range and approximatel y a 3 knot decrease i n airspeed from
the figures shown i n the Performance secti o n of this handbook.
Recommended Lean mixture provi d es best level crui s e performance
(generally cl o se to "best power" or maximum RPM).
Revi s i o n 4
65%
POWER
1 08
1 12
1 1 7
in level crui s e fl i ght, the exhaust ga
power
4 4
F
EXHAUST GAS
TEMPERATU R E
50° Ri c h of Peak EGT
Peak EGT
Figure 4-4. EGT Table
lean, from full ri c h or maximum RPM
slowly
slowly
Any change in al t i t ude or throttl e
Continuous operation at m ixtu re setti ngs
NORMAL PROCEDURES
55%
POWER
1 2.0 1 01
1 2.4 1 04
1 07
1 2.9
lean the mi x ture until an EGT
SECTION 4
POWER
NMPG
1 2.8
1 3.2
1 3.6
4-271