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3505582-65 – Honeywell Aerospace Pneumatic Turbine Engine Starter
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The Honeywell 3505582-65 is a high-performance, flight-critical pneumatic (air) starter motor engineered for the high-bypass turbofan engines of modern commercial and business jet aircraft. Specifically utilized on the Cessna Citation Longitude (Honeywell HTF7700L) and various Embraer Legacy/Praetor models, this starter is responsible for the initial rotation of the engine's high-pressure core (N2 spool) to the required ignition speed. Operating on the principle of high-velocity airflow, the 3505582-65 converts pneumatic energy from the Auxiliary Power Unit (APU), a ground power cart (huffer cart), or a cross-bleed from a running engine into the massive mechanical torque necessary to overcome the inertia and aerodynamic drag of a large turbine rotor.
The "3505582" series is renowned for its reliability and high power-to-weight ratio. It features an integrated overrunning clutch (sprag clutch) and a containment-shielded turbine wheel, ensuring that once the engine reaches self-sustaining speed, the starter safely disengages and remains protected against "over-speed" conditions.
Key Features
High-Torque Turbine Wheel: Features a precision-cast axial flow turbine designed to extract maximum work from low-pressure bleed air, ensuring rapid engine "light-off" even in "hot-and-high" airport conditions.
Integrated Sprag-Type Clutch: Provides an instantaneous, mechanical "freewheel" capability once the engine N2 speed exceeds the starter's drive speed, preventing the engine from "back-driving" the starter.
Containment Housing: The outer casing is specifically engineered to contain the rotating components in the highly unlikely event of a turbine wheel burst, meeting stringent FAA/EASA safety certification standards.
Shear-Section Drive Shaft: Includes a calibrated "weak point" in the drive shaft designed to snap if the engine experiences a mechanical seizure, protecting the starter’s gearbox and the engine's accessory gearbox (AGB) from catastrophic damage.
Low-Maintenance Splash Lubrication: Utilizes a self-contained oil system or interfaces with the engine's AGB oil supply to ensure the internal planetary reduction gears remain lubricated during the high-stress start cycle.
Technical Specifications
Part Number: 3505582-65
Manufacturer: Honeywell Aerospace (Mechanical Systems)
Component Type: Pneumatic Turbine Starter
Operating Medium: Compressed Bleed Air
Inlet Pressure: Typically 30–45 psig (Standard Start Envelope)
Weight: Approx. 22 lbs (10 kg)
Drive Interface: Quick-Attach/Detach (QAD) V-Band Flange
Certification: TSO-C149 (Aircraft Gas Turbine Starter)
Application Group: Engine Starting (ATA 80)
Aircraft Compatibility
Cessna Citation Longitude (Model 700): Primary starter for the HTF7700L engines.
Embraer Legacy 450 / 500: Utilizing the HTF7500E series.
Embraer Praetor 500 / 600: Modernized HTF-series engine platforms.
Note: The 3505582-65 is part of the HTF7000 engine family line-fit. Always verify the specific "dash number" against the Engine Illustrated Parts Catalog (EIPC) Section 80-11 to ensure compatibility with your engine's modification status.
Applications
The 3505582-65 is utilized for Core Engine Acceleration. Its primary roles include:
Ground Starting: Utilizing APU or GPU air to initiate the daily flight cycle.
In-Flight Re-Start: Providing the mechanical assist required to re-light an engine in the event of an in-flight flameout.
Engine Motoring: Rotating the engine without fuel/ignition for "dry-motoring" (to clear unburnt fuel) or "wet-motoring" (for leak checks).
Why Choose 3505582-65?
Choosing a genuine Honeywell 3505582-65 ensures Fastener Integrity and Thermal Stability. The internal planetary gears are subjected to massive "shock-loading" every time the starter valve opens. Non-OEM or improperly overhauled starters often suffer from "clutch-slippage" or "seal-perishing," which can lead to oil migration into the pneumatic system. The Honeywell OEM starter is calibrated for a specific Starter Duty Cycle, ensuring that even during multiple "back-to-back" start attempts, the unit does not exceed its internal temperature limits, preserving the life of the sprag clutch.
The 3505582-65 operates on the principle of Impulse Turbine Work governed by Bernoulli's Principle. As high-pressure air enters the scroll, it is directed through a nozzle, converting potential pressure energy into high-velocity kinetic energy. This air strikes the turbine blades, creating a torque ($T$) proportional to the mass-flow rate ($\dot{m}$) and the change in air velocity ($V$). This torque is then multiplied through a planetary reduction gearbox to provide the high-breakaway force required to start the N2 spool. The "Sprag Clutch" functions on the principle of Centrifugal Disengagement; as the engine accelerates away from the starter, the locking elements (sprags) are tilted by centrifugal force, physically separating the starter from the engine and preventing mechanical drag during flight.
Note: This is a flight-critical engine accessory. Installation must be performed by a certified A&P/AME. Prior to installation, the AGB mounting pad and drive-spline must be inspected for wear. The "V-Band" clamp must be torqued to the specific AMM value and safety-wired. Post-installation, a "Starter Valve Operational Check" and "Leak Check" are mandatory. Ensure the starter oil level (if applicable) is verified per the Honeywell Maintenance Manual.
