Type Rating Knowledge — Cessna 172S NAV III
Propeller
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Five words that settle everything
The 172S propeller is two bladed, FIXED PITCH, one-piece forged aluminium alloy, anodized to retard corrosion, and 76 inches in diameter. Each phrase closes off a whole class of system. Fixed pitch means there is no propeller control in the cockpit, no governor, no oil path to a hub, and no blue lever — the blade angle is what the factory forged into it. One-piece forged means the blades are not separately mounted and not ground-adjustable: pitch cannot be altered by a mechanic either, only replaced. And because the engine is DIRECT DRIVE, with no reduction gearbox, propeller speed equals engine speed: the tachometer is telling you about both at once.
- 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.