?unique=40ad667)
AC21-30 – Bombardier OEM Recline Cable & Conduit Assembly
Available now on the Airparts.aero Marketplace.
The AC21-30 is a precision-engineered mechanical actuation assembly designed for the cabin seating systems of Bombardier Learjet (C-21) and Textron Aviation aircraft. While often listed under the Textron parts catalog due to shared heritage in specialized seating, this assembly is a primary component for the Learjet 35/36 series (military designation C-21). The AC21-30 consists of a high-tensile stainless steel inner cable housed within a flexible, low-friction conduit. It serves as the critical link between the passenger’s seat-side recline lever and the gas-strut locking mechanism, enabling smooth and infinite adjustment of the seatback angle.
Engineered to survive the high-cycle environment of business and military transport, the AC21-30 is a "no-stretch" design that ensures the seat remains securely locked in the mandatory upright position for takeoff and landing. The assembly's compact dimensions and lightweight construction (0.16 lbs) make it ideal for the tight interior tolerances of Learjet cabin configurations.
Key Features
High-Flexibility Conduit: Features a specialized outer sheath that protects the inner cable from kinking or "binding" when routed through the complex, pivoting joints of a reclining seat frame.
Corrosion-Resistant Stainless Core: The inner "pull" cable is manufactured from multi-strand stainless steel (CRES), providing maximum tensile strength and resistance to the humidity and cleaning chemicals typical of aircraft cabins.
Low-Friction Internal Liner: The conduit is lined with a self-lubricating polymer (typically PTFE or Nylon), ensuring a smooth, consistent "pull" force throughout the life of the component.
Precision Swaged Terminations: Features factory-installed "Z-bend" or ball-end fittings designed for instantaneous attachment to the seat’s mechanical pulleys and release triggers.
Flame-Retardant Construction: Meets the stringent FAR 25.853 flammability and smoke density requirements for aircraft interior components.
Technical Specifications
Part Number: AC21-30
Manufacturer: Textron Aviation / Bombardier (OEM)
Component Type: Recline Cable / Conduit Assembly
Weight: 0.16 lbs (0.07 kg)
Approx. Dimensions: 15.6" (L) x 11.6" (W) x 1.25" (H)
Material (Inner): Stainless Steel Stranded Wire
Material (Outer): Reinforced Flexible Conduit
Certification: FAA-PMA / Part 25 Certified Interior Component
Aircraft Compatibility
Bombardier Learjet 35/36: (Standard civil and military C-21 variants).
Textron Aviation / Beechcraft: Specific executive seating configurations (verify per IPC).
Note: The AC21-30 is frequently utilized in "Quick-Change" or medevac-configured interiors where seat adjustability is vital for patient/crew comfort. Always verify the part number in your aircraft's Interior Illustrated Parts Catalog (IIPC) Section 25-20.
Applications
The AC21-30 is utilized for Cabin Interior Ergonomics and Safety. Its primary roles include:
Seat Recline Actuation: Translating the lever pull to the gas-strut trigger to unlock the seatback.
Mechanical Synchronization: Ensuring both sides of a wide seat frame release simultaneously to prevent twisting of the seatback.
Safety Compliance: Providing the mechanical return-to-lock force required to secure the seat for critical phases of flight.
Why Choose AC21-30?
Choosing the genuine OEM AC21-30 is essential for maintaining fastener preload and seat integrity. Non-OEM cables often suffer from "tensile creep"—permanent stretching over time—which leads to a "mushy" feel at the lever or, more dangerously, a failure of the seat to fully lock. The AC21-30 is calibrated to a specific break-away force, ensuring that even in high-vibration environments, the seat will not uncommanded-recline during a heavy landing or turbulence.The AC21-30 functions as a Flexible Mechanical Link governed by the physics of Tensile Displacement. The assembly is designed to transmit a "pull" force ($F$) over a specific distance ($d$) with minimal frictional losses ($f$). Because seat routing often involves multiple $90^\circ$ bends, the internal PTFE liner is critical to prevent "stick-slip" phenomena. The cable is designed with a Safety Factor (SF) of at least 1.5 times the maximum expected hand-pull force, ensuring that the internal strands do not reach their yield point even if an occupant forces the lever while the seat is jammed.
Note: This is a cabin interior component. Installation must be performed by a certified A&P/AME or an authorized interior specialist. Ensure the conduit is secured with "P-clips" or zip-ties as specified in the AMM to prevent interference with seat swivel mechanisms. After installation, a full "Lock and Release" check must be performed in all seat positions to verify the seat remains stationary when the lever is not engaged.
