VNE
163 KIAS
Never exceed speed.
Aircraft systems · Cessna 172S
Cessna 172S Systems
Explore how the airplane’s limitations, controls, engine, fuel, electrical, and flight instrument systems fit together, then open the applicable POH emergency procedures without leaving the lesson.
Module 01
Operating limitations
Use the tabs to move between speed, weight, engine, and fuel limits. These are the boundaries that frame every other system discussion.
VNO
129 KIAS
Maximum structural cruising speed.
VA at 2,550 lb
105 KIAS
98 KIAS at 2,200 lb and 90 KIAS at 1,900 lb.
VFE, flaps 10°
110 KIAS
Maximum flap extended speed at 10°.
VFE, flaps 10°–30°
85 KIAS
Maximum speed through the remaining flap range.
Window open
163 KIAS
Maximum window open speed.
Airspeed indicator markings · KIAS
404885129163
White 40–85
Green 48–129
Yellow 129–163
Red line 163
Normal max ramp
2,558 lb
Maximum takeoff and landing weight: 2,550 lb.
Utility max ramp
2,208 lb
Maximum takeoff and landing weight: 2,200 lb.
Baggage total
120 lb max
Area 1 limit 120 lb; Area 2 limit 50 lb. Combined maximum remains 120 lb.
Normal, flaps up
+3.8 / −1.52 g
Flaps down: +3.0 g.
Utility, flaps up
+4.4 / −1.76 g
Flaps down: +3.0 g.
Utility loading
Empty aft cabin
Baggage compartment empty and rear seat unoccupied.
Engine
IO-360-L2A
Lycoming, 180 BHP.
Maximum speed
2,700 RPM
Maximum engine speed.
Maximum oil temp
245 °F
Normal operating range begins at 100°F.
Oil pressure limits
20–115 PSI
Normal operating range: 50–90 PSI.
Vacuum
4.5–5.5 in Hg
Normal operating range.
Oil capacity
8 qt
Do not operate with less than 5 qt. Fill to 8 qt for extended flight.
Total fuel
56 gal
53 gallons usable.
Unusable fuel
3 gal
1.5 gallons in each tank.
Reduced fill
35 usable gal
17.5 usable gallons per tank to the bottom of each filler tab.
Approved fuel
100LL / 100
100LL is blue; 100 grade is green.
Takeoff flaps
0°–10°
Approved takeoff range.
Landing flaps
0°–30°
Approved landing range.
POH sourceSection 2: airspeed limits and markings, pages 2-4 to 2-5; powerplant and instrument markings, pages 2-5 to 2-6; weight, load factors, icing, fuel, and flap limits, pages 2-7 and 2-10 to 2-13. Oil capacity and minimum operating quantity: Section 7, page 7-21.
Module 02
Airframe and flight controls
Select a system to see the cockpit input, mechanical path, and airplane response described in the POH.
Primary flight controls
The ailerons, rudder, and elevator are manually operated through conventional cable systems and mechanical linkage.
- Control wheel movement operates the ailerons and elevator.
- Rudder and brake pedals operate the rudder.
- The design uses conventional hinged ailerons and rudder/elevator surfaces.
The POH describes the structure as all-metal with integral wing fuel tanks.
POH sourceSection 7, airframe and flight controls, pages 7-5 to 7-6; center pedestal and ground control, page 7-12; wing flap system, page 7-13; landing gear system, page 7-14.
Module 03
Engine, induction, oil, and propeller
The powerplant is a direct-drive, air-cooled, fuel-injected Lycoming connected to a fixed-pitch propeller. Select a stage in the flow to reveal its function.
4opposed cylinders
180 hpat 2,700 RPM
8 qtoil capacity
76 inpropeller diameter
Filtered induction air
Normal induction air enters through a filter. If the filter becomes blocked, the alternate air door is spring-loaded to open and supply unfiltered air from inside the lower cowl.
The POH states that alternate air use causes approximately a 10 percent power loss at full throttle.
POH sourceSection 7: engine and controls, pages 7-19 to 7-20; engine lubrication, page 7-21; ignition and air induction, page 7-22; exhaust, cooling, and propeller, page 7-23.
Module 04
Fuel system explorer
Change the selector position to trace the usable source. The diagram teaches system routing, not fuel endurance or real-time quantity.
LEFT TANK
RIGHT TANK
BOTH
Reservoir → pumps → fuel / air control
Selected usable fuel
53 gal
Both tanks feed. This is the required selector position for takeoff, climb, landing, and prolonged slips or skids.
System path: Fuel flows by gravity from the wing tanks through the selector to the reservoir, then through the auxiliary and engine-driven pumping path to the fuel/air control unit and distribution valve.
Quantity cues: Each tank contains about 1.5 gallons unusable when the indicator reads empty. The LOW FUEL caution activates below approximately 5 gallons in a tank for more than 60 seconds.
POH sourceSection 7: fuel system overview and capacities, pages 7-23 to 7-24; quantity and low-fuel indication, page 7-25; venting, reduced fill, and selector use, page 7-26; fuel drains, page 7-28. Section 2 fuel limitations and selector capacities, pages 2-11 and 2-13.
Module 05
Electrical power and buses
Toggle the BAT, ALT, and AVIONICS switches to see which parts of this simplified bus model are energized. This is a learning view, not a substitute for the wiring diagram or checklist.
Primary busesSplit main distribution
Essential busEssential loads
Avionics busesAvionics loads and cooling fan
Alternator output60-amp belt-driven alternator
28-volt direct-current system
The system uses a 24-volt battery and a 60-amp belt-driven alternator. A split rocker master separately controls BAT and ALT functions.
Alternator online
VOLTS
Primary, essential, and avionics buses are energized.
The VOLTS annunciator activates below 24.5 volts. The ammeter indicates battery charging or discharging current.
POH sourceSection 7: electrical system architecture, page 7-29; master and avionics master switches, pages 7-33 to 7-34; ammeter and low-voltage indication, pages 7-34 to 7-35; avionics cooling fan, page 7-47.
Module 06
Flight instrument support systems
Select an input system to follow the source, path, and instruments it supports.
Pitot-static system
Heated pitot tube + static port
Pressure lines
ASI · altimeter · VSI
The pitot tube supplies ram air pressure to the airspeed indicator. Static pressure is supplied to the airspeed indicator, vertical speed indicator, and altimeter. An alternate static source is installed below the throttle.
The heated pitot tube is mounted on the lower surface of the left wing. The external static port is on the lower left side of the forward fuselage.
POH sourceSection 7: annunciator system, page 7-32; pitot-static system and alternate static source, page 7-41; vacuum system, pages 7-43 to 7-45; stall warning, page 7-46.
Module 07
Emergency and malfunction procedures
Choose a condition to open the POH sequence in checklist order. These procedures are presented for familiarization and must be checked against the approved POH for the specific aircraft.
Emergency procedure
Engine failure during takeoff roll
- Throttle: IDLE
- Brakes: APPLY
- Wing flaps: RETRACT
- Mixture: IDLE CUT OFF
- Ignition switch: OFF
- Master switch: OFF
POH Section 3, page 3-4
Checklist discipline: This interface is not a memory-item endorsement and does not replace immediate use of the approved airplane checklist when conditions permit.
POH sourceSection 3: emergency airspeeds, page 3-3; engine failures, pages 3-4 to 3-5; engine fire, page 3-7; electrical fire, page 3-8; inadvertent icing, pages 3-9 to 3-10; static blockage, page 3-10; electrical malfunctions, page 3-11; vacuum malfunction, page 3-12.
Module 08
Source and applicability
The citations throughout this page use the page numbers printed inside the POH, not the PDF viewer’s file-page counter.
Printed pages 2-1 through 2-15/2-16. Used for airspeeds, markings, operating weights, load factors, fuel, flap, and icing limitations.
Printed pages 3-1 through 3-23. Used for emergency airspeeds, engine failure, fire, icing, static, electrical, and vacuum procedures.
Printed pages 7-1 through 7-50. Used for airframe, engine, fuel, electrical, flight instrument, warning, and support-system descriptions.
Cessna Model 172S NAV I/NAV II Information Manual, serials 172S8001 through 172S10431, Revision 5A dated 25 March 2016.
ImportantThis learning page intentionally excludes POH Sections 1, 4, 5, 6, 8, 9, and supplements. Consult the full approved manual for operating procedures, performance, weight and balance, handling, maintenance, installed equipment, and supplemental limitations.