GRUMMAN AMERICAN
FOR TRAINING USE ONLY – SECTION 7
MODEL GA‐7/COUGAR
AIRPLANE & SYSTEMS DESCRIPTIONS
7‐23
Issued: April 10, 1978
AIR INDUCTION SYSTEM
The engine air induction system receives ram air through the engine air intake inside the engine cowling. The ram
air passes through a duct to the air filter located directly behind the carburetor where the air is filtered prior to
entry into the carburetor. When carburetor heat is being applied, a flapper valve in the intake to the air filter is
closed off and the carburetor draws unfiltered heated air from a shroud around the engine exhaust muffler.
EXHAUST SYSTEM
Exhaust gas from each cylinder passes through riser assemblies to a muffler and tailpipe. The muffler is
constructed with a shroud around the outside, which forms a heating chamber for cabin and carburetor heat.
ENGINE COOLING
Ram air for engine cooling enters through the air intake openings in the engine cowl. The air is directed around
the cylinders and other engine areas by baffling, and then exhausted through an exit duct in the bottom of the
engine cowling.
COWL FLAPS
Each engine has a cowl flap located in the lower cowling. The cowl flaps control engine heat and are controlled by
manual control knobs located on the bottom of the control quadrant (Figure 7‐8). Pulling the knobs out closes the
cowl flaps and the flaps are opened by pushing the knobs in. The cowl flaps can be set at any desired position form
closed to full open and can be locked in a position by turning the control knob to the right.
ENGINE MOUNTS
Each engine is mounted to the nacelle engine support structure at four mount points. Each of these mounts
contains rubber isolators capable of sustaining operational loads and providing absorption for engine vibration.
PROPELLERS
The airplane is equipped with Hartzell all metal, two bladed, constant speed, full feathering, governor regulated
propellers. The propellers are operated by oil pressure from the engine oil system. The oil pressure is boosted by
the propeller governor gear pump. Oil pressure from the governor drives the blades toward low pitch (increasing
RPM) and springs, along with air pressure in the hub, and counterweights drive the blades toward high pitch
(decreasing RPM).
