0851HT-1 - Collins Aerospace Boeing OEM 737 Pitot Tube Probe

0851HT-1 – Collins Aerospace Boeing OEM 737 Pitot Tube Probe

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The Collins Aerospace 0851HT-1 is a flight-critical, OEM electrically heated low-drag pitot probe engineered for high-performance speed sensing across the Boeing 737 Next Generation (NG) and 737 MAX fleets. In modern air transport operations, pitot-static systems form the foundational input for primary flight displays (PFDs), flight management computers (FMCs), and safety systems. The 0851HT-1 is aerodynamically optimized to capture total stagnation pressure ($P_t$) with unmatched precision, even at extreme angles of attack and sideslip, ensuring that flight crews and flight control computers receive highly accurate, real-time airspeed data.

This probe is equipped with a robust, high-performance 115 VAC internal heating element. This system provides advanced de-icing capabilities, keeping the inlet free of ice accumulation during high-altitude, supercooled water droplet conditions and high-concentration solid ice environments. The probe features a specialized low-drag design that minimizes aerodynamic interference and parasitic boundary layer separation along the forward fuselage skin, directly enhancing overall fuel efficiency and flight path stability.

Through 30 years of hands-on experience in the hangar, I can tell you that the 0851HT-1 represents the gold standard in air data precision. In commercial transport, there is absolutely zero margin for error in airspeed indication. Selecting an authentic, factory-certified Collins Aerospace 0851HT-1 guarantees absolute compatibility with the aircraft's Air Data Modules (ADMs). Sourcing this OEM component ensures compliance with RVSM (Reduced Vertical Separation Minimum) standards, maintains Type Certificate data compliance, and protects your fleet from autopilot dropouts, erratic airspeed indications, and costly flight delays or airworthiness write-ups.

*** MANDATORY REPLACEMENT PART: 0851HT-2 - SEE DOCUMENTS SECTION AND REVIEW REPLACEMENT DOCUMENT FROM COLLINS ***

Key Features

• Advanced Low-Drag Aerodynamic Envelope: Specially profiled to minimize fuselage boundary layer disruption and aerodynamic resistance, contributing to reduced fuel burn and lower parasitic drag.

• High-Capacity 115 VAC De-Icing Heater: Features an integrated, robust ceramic-insulated resistive heater element that operates continuously under alternating current to completely eliminate ice accretion under extreme supercooled liquid conditions.

• Erosion-Resistant Surface Treatment: Protected by a high-purity electro-deposited nickel plating designed to withstand severe sand, rain, and volcanic ash abrasion.

• Hermetically Brazed Joint Integrity: Internal pressure tubes and structures are assembled using advanced nickel-based brazing alloys, preventing high-vibration stress cracking and internal pressure leaks.

• Dual-Release Global Compliance: Fully qualified to meet FAA TSO-C16 and EASA regulations, ensuring a seamless return-to-service with dual-release certifications.

• Single Electrical Connector Interface: Features a simplified, heavy-duty rear connector bay that allows quick line replacement and reliable, moisture-sealed harness mating.

Technical Specifications

• Part Number: 0851HT-1

• Alternative Boeing Part Number: S232N911-6

• Component Type: Electrically Heated Low-Drag Pitot Probe

• OEM Manufacturer: Collins Aerospace (formerly Rosemount Aerospace Inc. / Goodrich / UTC Aerospace Systems)

• CAGE Code: 59885

• Heater Voltage Rating: 115.0 Volts AC (Alternating Current)

• Casing Material: Corrosion-resistant steel (CRES) or premium brass alloy substrate

• Finish: High-purity electroplated nickel

• ATA Chapters: ATA 34 (Navigation / Pitot-Static System) and ATA 27 (Flight Controls / Yaw Damper / Elevator Feel)

• ECCN: 9A991.d

• NSN / NIIN: 6610-01-583-8448 / 015838448

• Weight: ~1.2 lbs (nominal)

• Certification: FAA TSO-C16, AS393, FAA Form 8130-3 / EASA Form 1 Dual Release

Aircraft Compatibility

• Boeing 737 Next Generation (NG) Series: 737-600, 737-700, 737-800, 737-900, 737-900ER

• Boeing 737 MAX Series: 737 MAX 7, 737 MAX 8, 737 MAX 9, 737 MAX 10, 737-8200

• Boeing Business Jet (BBJ) Series: BBJ 737-700, BBJ 737-800, BBJ 737-900ER

• Boeing 757 Series: (Select configurations specifying Boeing P/N S232N911-6)

• Note: The aircraft’s Illustrated Parts Catalog (IPC) is the final and absolute authority for verification of part numbers, specific serial-number effectivity, and localized system mapping.

• 737NG-800MMA
• 737NG-900ER
• 737NG-AEW&C
• BBJ 737-900ER
• 737MAX-9BBJ
• 737NG-700
• 737NG-800BJ
• 737-600
• 737NG-700C
• 737 MAX 8
• 737-900
• 737 MAX 9
• 737MAX-9
• 737-900ER
• 737NG-900ERBJ
• 737NG-600
• 737-700C
• BBJ 737-800
• 737NG-800BCF
• 737MAX-8BBJ
• 737-700
• 737NG-900
• 737MAX-10
• 737MAX-7
• 737MAX-8200
• 737NG-700BJ
• 737-800
• 737NG-800
• BBJ 737-700
• 737MAX-8

Applications

• Primary Airspeed Data Sensing: Captures total stagnation pressure for input directly into the Captain’s, First Officer’s, or Auxiliary Air Data Modules (ADMs) to drive the primary airspeed indicator and FMC calculations.

• Elevator Feel System Reference: Supplies dynamic pressure to the Elevator Feel Computer on the vertical stabilizer, modulating the hydraulic control column force feedback based on airspeed.

• Autopilot & Flight Control System Input: Provides real-time dynamic pressure inputs to the Autopilot Flight Director System (AFDS) to govern autothrottle, pitch, and yaw damper logic.

Why Choose 0851HT-1?

In commercial aviation, a single instrument error can compromise passenger safety and ground an aircraft immediately. Sourcing the genuine Collins Aerospace 0851HT-1 OEM probe ensures that your cockpit instruments receive inputs within the absolute micro-bar tolerances intended by Boeing's design engineers.

Non-certified or imitation probes frequently experience internal heater circuit failure, deteriorating insulation resistance over time when subjected to high-vibration engine harmonics and severe thermal cycling. When moisture penetrates a sub-standard probe, it causes micro-corrosion of the heating elements, resulting in a short-to-ground. On a Boeing 737, an erratic pitot signal from the vertical stabilizer probes can trigger the highly disruptive "FEEL DIFF PRESS" light in flight, forcing crews to execute emergency checklist procedures. Sourcing an authentic OEM 0851HT-1 with an FAA 8130-3 Dual Release through Airparts.aero ensures total airworthiness compliance, RVSM conformity, and eliminates unpredicted AOG events due to premature airspeed sensor failures.

The operational physics of the 0851HT-1 pitot probe are grounded in fluid dynamics and the stagnation of compressible flow. As high-velocity air molecules enter the precision-bored nose entry of the probe, their relative kinetic energy is converted into static thermal energy at the stagnation point, where local fluid velocity drops to zero. This stagnation pressure is transmitted via internal hermetically brazed stainless steel conduits to the Air Data Modules (ADMs). The ADM mathematically extracts dynamic pressure by subtracting static pressure obtained from the static ports, in accordance with Bernoulli's compressible flow equations.

Because the boundary layer thickness along the forward fuselage changes with the Reynolds number, the "low-drag" swept contour of the 0851HT-1 strut is engineered to position the sensing orifice outside the boundary layer's turbulent transition zone, securing a laminar intake profile. Furthermore, to protect this delicate thermodynamic and fluidic boundary from freezing, the 0851HT-1 utilizes a highly sophisticated coaxial magnesium oxide (MgO) mineral-insulated heating element. Under 115 VAC excitation, this design maximizes heat flux transfer directly to the leading edge of the probe while maintaining electrical isolation. This specialized thermal distribution prevents ice accretion without causing localized heat-induced density changes in the air surrounding the stagnation point, ensuring RVSM airspeed measuring compliance remains intact even in severe meteorological icing zones.

Note: The 0851HT-1 is a flight-critical instrument. Prior to installation, technicians must perform a comprehensive insulation resistance check (megger test) of the heater element at 500 VDC to ensure a minimum resistance threshold of 100 megaohms. Any contamination, moisture, or internal micro-cracks will result in immediate system warning lights (e.g., pitot heat fail or elevator feel diff press). Always use approved, non-conductive tooling when clearing or applying aerodynamically critical sealant around the probe's base plate. Never touch or apply protective covers to the probe while the 115 VAC pitot heat is active, as surface temperatures rapidly exceed 400°F (204°C). Installation, calibration, and subsequent leak checks must be performed by a certified A&P/IA mechanic or authorized FAA/EASA repair station in strict compliance with the Boeing 737 Aircraft Maintenance Manual (AMM) Chapter 34-11.