A Lycoming IO-540-T4B5 fuel injected, air-cooled, six cylinder, normally aspirated engine rated for 260 HP at 2,700 RPM powers the 115 and 115AT, and a Lycoming TIO-540-AG1A turbocharged engine rated for 270 HP at 2,575 RPM powers the 115TC. The engine is equipped with dual magnetos with gear-driven independent drives, shielded harness assemblies, radio shielded spark plugs, and two independent vacuum pumps. TBO is 2000 hours for either engine. The cowl is easily removed for quick access to the engine compartment for routine maintenance.
Engine instruments are located in the center of the instrument panel and provide the means for monitoring the operation and condition of the engine. Instruments include the tachometer, manifold pressure gauge, fuel flow/fuel pressure gauge, cylinder head temperature, EGT and oil pressure/oil temperature indicator. These instruments are electrically operated.
The engine control quadrant is located on the center console. It has a standard configuration (left to right) of: Throttle, Propeller and Mixture. The 115 utilizes a manual Cowl Flap control, while the 115TC uses an electric control.
The Commander is equipped with a McCauley, all-metal, three-bladed, constant speed propeller which is 77 inches in diameter. Each prop is dynamically balanced, and the three-bladed design reduces noise and vibration.
Induction Ram Air for the engine enters through a duct in the front baffle of the engine where it is routed to the induction air box and filter before entering the engine. The induction air box also has an alternate air passage to bypass the filter if needed.
The engine is equipped with a rugged, stainless steel, crossover exhaust tube, feeding into a single tailpipe which exits the lower portion of the engine cowl. The exhaust is a tuned, stainless steel inconel system for long life and durability. A heat muff provides cabin and windshield heat.