Alternate Static Source SenecaV.UK

Cessna 172 Alternate Static Source. The Aircraft Pitot Static System AeroToolbox The system is standard with a heated pitot head under the left wing and two static ports on either side of the nose cowling This table is included because of the fact that the Alternate Static Port on 172s is inside the cabin

201314213 Cessna Alternate Static Source Valve (201314213)
201314213 Cessna Alternate Static Source Valve (201314213) from aircraftpartsandsalvage.com

The pedestal looks like the 172R and newer and I would think it would be there in the same location Is there a "stock" alternate static source or was it optional

201314213 Cessna Alternate Static Source Valve (201314213)

Is (was) the alternate static source not standard? I can't find the plumbing, bracket, placard, etc Thus, changes in cabin pressure (even really small ones) can have an impact on the static pressure that the system is using and hence on the indicated airspeed The system is standard with a heated pitot head under the left wing and two static ports on either side of the nose cowling

201314213 Cessna Alternate Static Source Valve (201314213). Example from a Cessna 172 POH demonstrating the impact of the alternate static source has on indicated airspeed in different vent and window configurations The things the table mentions like windows and heat vents all influence the pressure in the cabin, and hence the airspeed

2008 Cessna 172SP Steel Aviation. Is (was) the alternate static source not standard? I can't find the plumbing, bracket, placard, etc An engineer at Cessna figured out that this arrangement of shapes and locations works well enough to compensate for Bernoulli and gets you very close to the "not moving" air pressure