Type Rating Knowledge — Cessna 172S NAV III
Engine
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Eight words that describe the whole engine
The 172S is powered by a direct drive, horizontally opposed, four cylinder, overhead valve, air cooled, fuel INJECTED engine with a wet sump lubrication system: a Lycoming IO-360-L2A rated at 180 horsepower at 2700 RPM. Each of those words rules something out. Direct drive means the propeller turns at engine speed, with no reduction gearbox — which is why the tachometer is also your propeller speed. Air cooled means there is no radiator or coolant to check, and cooling depends on airflow, so it depends on airspeed. Fuel injected means there is no carburettor and therefore no carburettor ice and no carburettor heat control to find in the cockpit. Wet sump means the oil lives in a sump under the engine and returns there by gravity, with no separate oil tank.
- STARTER — Starter, on the front of the engine — the one accessory here that CONSUMES electrical power rather than serving another system.
- ALTERNATOR 60A — Belt driven 60 A alternator on the front of the engine — belt driven, which is a failure mode a gear-driven accessory does not have.
- PROPELLER 76 IN — Two bladed fixed pitch McCauley 1A170E/JHA7660, 76 inches. Direct drive: propeller speed equals engine speed, so the tachometer reads both.
- IO-360-L2A 180 HP @ 2700 RPM — Direct drive, horizontally opposed, four cylinder, overhead valve, air cooled, fuel injected, wet sump. Everything on this diagram is driven by it.
- DUAL MAGNETOS — Two engine driven magnetos on the rear accessory case — self-generating, which is why the engine keeps running with the master switch off.
- VACUUM PUMP — Engine driven vacuum pump on the rear accessory case — it drives the standby attitude indicator, so it is the engine’s stake in the instrument system.
- FUEL PUMP — Engine driven fuel pump on the rear accessory case — the fuel system’s normal supply, needing no electrical power.
- FULL-FLOW OIL FILTER — Full flow oil filter on the rear of the accessory case, holding the ninth quart of oil.