The 487-352 is a Piper airframe spring used in the seat back adjustment system, specifically identified as the outboard seat back adjustment spring. It is part of the mechanical seat assembly that allows the pilot or passenger seat back to be adjusted and returned smoothly between positions.

In Piper light aircraft seating systems (commonly PA-series aircraft such as Arrow, Archer, and similar variants), this spring works as part of the seat recline/adjustment mechanism. It provides tension and return force for the seat back locking and adjustment system, ensuring the seat remains securely positioned under pilot weight, vibration, and in-flight loading conditions.

The “outboard” designation refers to its installation position on the outer side of the seat frame, typically paired with an inboard counterpart spring. Together, these springs balance the load across the seat back adjustment tube and help maintain consistent detent engagement and smooth motion when adjusting the seat back angle.

Because it is a cyclic mechanical component, it is subject to fatigue over time due to repeated adjustment, occupant loading, and airframe vibration. Wear or loss of tension can lead to loose seat feel, poor locking engagement, or uneven seat back resistance.

This part is commonly referenced in Piper maintenance and parts catalogs and is often replaced during seat refurbishment or interior maintenance.

Key features include:

Piper 487-352 seat back adjustment outboard spring
Used in pilot/passenger seat back recline mechanism
Provides return force and tension in seat adjustment system
Works in conjunction with inboard seat spring (paired assembly)
Material: high-tensile spring steel designed for cyclic loading
Installed on seat frame outboard side (left or right depending on seat)
Ensures stable seat locking and smooth adjustment movement
Subject to fatigue, wear, and loss of elasticity over time
Common in Piper PA-series light aircraft seating systems
Replaced during seat maintenance, refurbishment, or overhaul