Kind of confusing,where is the alternate air intake?

[leo_ding]

Hi,I fly da20,just kind of confusing of the alternate air intake postion for DA20..

DA20 has a fuel injection engine,I think the alternate air in take is behind the primary air in take ( near the exhaust air)..

and my classmates says it's in the front... he asked the maintenance,I can't find that in the POH..

anyone have a idea, or generally speaking where is the alternate air in take should be?

thanks!

[Colonel Sanders]

The alternate air intake on a certified installation
of a fuel-injected engine can either be manually
or automatically (generally spring-loaded) selected.

The alternate intake is simply inside the cowling -
it does NOT require heat from the exhaust, like
with a carburetor - and can generally be easily
found by removing the cowling.

This is the case with the Mooney M20J with the
angle-valve Lyc 200hp IO-360A3B6D, and also
with the Maule M4-210C with the TCM IO-360A
and also the Pitts S-2B with the Lyc AEIO-540D4A5.

[nightbird]

This is the alternate air of a fuel injected 172s. This one is spring loaded.

3545.jpg (9.94 KiB) Viewed 3348 times

[rob-air]

Could it be right beside the filtered air intake? The opening with wire mesh.

[Colonel Sanders]

The alternate air intake on a fuel-injected engine
will not be visible externally because of the possibility
of impact icing plugging it up.

Mind you, those crazy sumb1tches at Lycoming
certified that horrible dual mag, so I guess anything
is possible.

[Trematode]

If I'm remembering right the da20 had a continental io 240. The alternate air was manually operated with a lever on the throttle quadrant that actuated the alternate intake which was on the airbox just aft of the filtered primary intake, and protected inside the cowl.

Rob: I think the external mesh-protected opening next to the engine air intake was for cabin air, which could be routed around the heat exchanger to provide heat if desired.

[pelmet]

Seem to remember the Mooney M20E having a knob to pull allowing more direct airflow to the engine giving an extra inch of MP. But I can't remember if there was an alternate air valve in addition to this. Am planning an M20J checkout but haven't gotten to it yet.

[Colonel Sanders]

Yeah, the M20J had the "ram air" knob to pull
to bypass the air filter. Gave maybe another
inch of MP.

That was different from the alternate air, which
was a spring-loaded door on the intake - automatically
actuated, like the Maule.

The Pitts has a manually activated alternate
air intake. Never used it, never will. For certification
purposes only.

[Cessna driver]

If I'm remembering right the da20 had a continental io 240. The alternate air was manually operated with a lever on the throttle quadrant that actuated the alternate intake which was on the airbox just aft of the filtered primary intake, and protected inside the cowl.

Rob: I think the external mesh-protected opening next to the engine air intake was for cabin air, which could be routed around the heat exchanger to provide heat if desired.

This is true. Looked at it last week with the cowl off.