PST305 – Aerosonic 24 Volt Heated Pitot-Static Probe
Available now through the AirParts Aero marketplace.
Overview Section
The Aerosonic PST305 is a high-precision, Heated Pitot-Static Probe designed for 24V/28V aircraft electrical systems. This critical aerodynamic sensor combines both pitot (impact) pressure and static pressure sensing into a single, aerodynamically "clean" unit.1 By providing the raw pneumatic data for airspeed, altitude, and vertical speed, the PST305 is a foundational component of the aircraft's primary flight instrumentation.2
Engineered for reliability in all-weather operations, the PST305 features an integrated heating element that prevents ice accretion within the pressure ports.3 This "anti-icing" capability is essential for flight in known icing (FIKI) conditions, ensuring that the pilot’s airspeed and altitude readings remain accurate even in the most hostile atmospheric environments.4
Key Features Section
Dual Sensing Architecture: Integrates pitot and static pressure ports into one mast, reducing the number of fuselage penetrations and minimizing aerodynamic drag.
24V/28V High-Wattage Heater: Equipped with a powerful internal heating coil that maintains a surface temperature above freezing, preventing port blockage during inadvertent or intentional icing encounters.5
Corrosion-Resistant Finish: Features a high-luster chrome or nickel plating that resists the abrasive effects of dust and rain while maintaining the smooth surface required for laminar airflow.
Aerodynamic Stability: Designed to provide "neutral" static pressure sensing, minimizing position errors caused by changes in the aircraft's angle of attack.
Sump/Drain Compatibility: Typically designed with internal water traps and drain holes to prevent moisture from entering the pneumatic lines leading to the cockpit instruments.
Standardized Mounting: Features a robust flange or mast-mount design compatible with a wide range of General Aviation and corporate airframes.
Technical Specifications Section
| Specification | Detail |
| Part Number | PST305 |
| Manufacturer | Aerosonic Corporation |
| Operating Voltage | 24 - 28 VDC |
| Heater Power | Typically 150 - 250 Watts (Verify per specific mod) |
| Pressure Outputs | Pitot (Impact) and Static |
| Material | Plated Brass or Stainless Steel |
| Heater Type | Anti-Icing (Constant Current or Thermally Protected) |
| Operating Speed | Calibrated for subsonic GA and Turboprop speeds |
| Certification | FAA-TSO C16 and TSO-C2 |
Aircraft Compatibility Section
The PST305 is a common sight on the wing or fuselage of several high-performance aircraft found in the AirParts Aero inventory:
Piper Aircraft: Extensively used on the Piper PA-31 Navajo, PA-42 Cheyenne, and late-model PA-32 series.
Cessna Turboprops: Found on various Cessna 425 (Conquest I) and 441 (Conquest II) variants.
Beechcraft: Compatible with several King Air and Duke configurations requiring heated dual-sensing probes.
Special Mission Platforms: Often used on aerial surveillance and mapping aircraft due to its high accuracy.
Technical Applications & Safety
The PST305 is a safety-of-flight component. A blockage in the pitot port can result in a "frozen" or zero-reading airspeed indicator, while a static port blockage can cause the altimeter to freeze and the VSI to return to zero.
Safety Warning: The heater on the PST305 becomes extremely hot (over 200°F) within seconds of activation on the ground. Never touch the probe when the "Pitot Heat" switch is ON. Always ensure the probe cover is removed before flight, as a melted cover can permanently block the precision sensing ports.
Technical Engineering Insight
The engineering value of the Aerosonic PST305 lies in its Static Source Error Correction (SSEC) Optimization. Sensing static pressure from a moving mast is notoriously difficult because the air rushing past the probe creates a low-pressure zone (Bernoulli's Principle). Aerosonic solves this by positioning the static ports at a mathematically precise "dead zone" on the probe body where the local pressure equals the ambient atmospheric pressure.
Furthermore, the PST305 utilizes a High-Density Heating Coil that is brazed directly to the internal pressure tubes. This ensures that heat is transferred efficiently to the "nose" of the probe where ice is most likely to form first. Choosing the genuine Aerosonic unit through AirParts Aero ensures that your airspeed indications remain linear and your altitude readings remain TSO-accurate, protecting your aircraft during IFR operations in challenging weather.
Installation & Maintenance Addendum
Alignment: The probe must be mounted perfectly parallel to the longitudinal axis of the aircraft. Even a 1-degree misalignment can introduce significant airspeed errors.
System Leak Check: After installation, a Pitot-Static test per FAR 91.411 is mandatory to ensure no leaks exist at the flare fittings.
Heater Operational Test: Use a "Pitot Heat" ammeter check to verify the heater is drawing the correct current; a "warm" probe on the ground does not always mean it can handle the cooling loads of high-altitude flight.