induction system

normally aspirated induction system consists of

air scoop used to collect inlet air and ducting to transfer air

alternate air

opens in the event of a plugged intake filter

how do we open alternate air duct

manually by pilot or automatically by difference in pressure acting on a spring loaded door

types of induction icing

carb 

throttle

impact

carb ice

moisture in the air inside the carb freezes as temperature drops through the venturi and as fuel vapourizes

throttle ice

forms on the back side of the throttle valve

impact ice

produced from snow, ice or rain impacting the inside of the scoop, frame or filter

ice detection and removal method

carb heat system

carb heat system

directs unfiltered heated air from the heat muff into carb

carb air temperature gauge

measured at carb entrance

warns of induction ice formation and induction system condition

types of air filters

reusable screen filled with a fibre core (flock)

paper

polyurethane foam filter soaked in glycol solution

paper filter maintenance

• clean with low pressure air

• life limit 500hours

• AD for annual inspection for tears and pinholes

foam filter maintanance

• replace every 100 hours or annually

• inspect screen for security, proper mounting hardware and cracking

intake manifold consists of

pipes and couplings that provide fuel/air mixture or airflow from the fuel metering device to the cylinders

what are the balance/crossover tubes used for in an intake manifold

ensures equal system pressure for cylinders

types of intake manifolds

downdraft and updraft

downdraft intake manifold

sits on top of cylinders and directs air down

updraft intake manifold

sits below cylinders

air flows from inlet to throttle body to tubes to risers mounted to cylinders

CAT shows momentary rise

backfire

CAT shows continuous increase

sustained induction fire

why is carb heating a risk

carbon monoxide risk in the cabin

lycoming engine manifold is located

inside oil sump

benefits of having manifold in oil sump in lycoming

heats mixture for vapourization

cools oil