Light Cessna aircraft - at least the high wing single engine line - have commonly made use of a solid state pneumatic stall warning system. The system is fairly unique to Cessna airplanes and makes use of the fact that negative pressures form over the leading edge of the wing near the critical angle of attack, causing a reverse flow of air through the warning system and causing a horn in the cockpit to sound. Most other light aircraft make use of a movable tab with activates an electric switch when depressed by airflow near the critical AoA, causing a chime, horn or other aural cue in the cockpit alerting the pilot to an impending stall. Here's the question: What are the pros and cons of each of these systems? From brainstorming, I can come up with the following:
Pneumatic Stall Warning Systems:
- Solid State; has no moving parts which can break or become immobilized or altered by neglect, damage or airframe icing.
- Does not require electrical or other sources of power from engine or elsewhere to work.
- Orifice can become blocked by FOD or airframe icing, causing the system to become inoperative.
Mechanical Stall Warning Systems:
- Simple operating and mature technology.
- Can be electrically heated to prevent immobilization by airframe icing, though this is not always the case depending on the aircraft.
- Moving parts which can break.
- Tab can be bent by maintenance or neglect, causing system to operate erroneously and give false readings.
- Can be immobilized by airframe icing, rendering the system inoperative.
Can anybody think of other pros and cons for each of these systems?