494-721 - Piper Aircraft OEM Seal Wiper

494-721 – Piper Aircraft OEM Seal Wiper

Available now on the Airparts.aero Marketplace.

Overview

The Piper Aircraft 494-721 is a genuine OEM wiper seal, a flight-critical component engineered for the landing gear shock struts of high-performance Piper twin-engine aircraft. This is not a primary pressure seal, but a highly specialized scraper or wiper ring. Its sole function is to act as the first line of defense for the entire hydraulic sealing system, meticulously cleaning the chrome piston rod as the landing gear retracts. Manufactured from a highly durable, abrasion-resistant elastomer, the 494-721 is essential for ensuring the long-term, leak-free performance of the landing gear oleo-pneumatic strut.

Key Features

• Contaminant Scraper Design: Features a precision-molded, sharp leading edge designed to scrape and dislodge contaminants—such as dirt, mud, ice, and runway debris—from the landing gear piston before it retracts into the strut cylinder.
• Primary Seal Protection: By preventing abrasive particles from reaching the main hydraulic pressure seals (U-cups or O-rings), the wiper seal dramatically extends the life of these critical components and is the primary defense against strut leaks caused by seal damage.
• High-Performance Elastomer: Fabricated from a specialized, high-durability polyurethane or similar advanced elastomer. This material is selected for its exceptional toughness, abrasion resistance, and resilience, allowing it to maintain a sharp wiping edge through thousands of landing cycles.
• Fluid & Environmental Resistance: The material compound offers excellent resistance to degradation from aviation hydraulic fluids (e.g., MIL-H-5606), de-icing fluids, and environmental factors like ozone and UV radiation.
• Genuine Piper OEM Part: As a genuine factory component, it guarantees the correct material durometer (hardness), precise dimensions, and lip geometry required for an effective wiping action on the specified landing gear struts, ensuring an airworthy and reliable installation.

Technical Specifications

• Part Number: 494-721
• Component Type: Wiper Seal / Scraper Ring
• Primary Application: Landing Gear Oleo-Pneumatic Shock Strut
• Material: High-Durability, Abrasion-Resistant Polyurethane/Elastomer
• Installation: Press-fit into the strut gland nut or end cap.
• Certification: FAA Production Approval

Aircraft Compatibility

The 494-721 is the specified OEM wiper seal for the main and/or nose landing gear on a wide range of Piper's most successful cabin-class twin-engine aircraft. It is imperative to consult the specific aircraft's Illustrated Parts Catalog (IPC) for final verification.

• Primary Aircraft Families:
  • PA-31: Navajo, Chieftain, Mojave
  • PA-31P-350: Pressurized Navajo
  • PA-42: Cheyenne
  • T1020

Applications

The 494-721 is a critical component for landing gear system reliability and maintenance:

• Landing Gear Overhaul: A mandatory replacement item whenever a landing gear strut is disassembled for overhaul or resealing.
• Preventative Maintenance: Replacing the wiper seal is a key preventative action to protect the more difficult-to-replace internal hydraulic seals from damage.
• Leak Prevention: A healthy, sharp wiper seal is the best defense against the primary cause of strut leaks—piston seal damage from contaminants.

Why Choose 494-721?

The long-term reliability of an aircraft's landing gear depends on the cleanliness of its hydraulic system. The 494-721 wiper seal is a relatively inexpensive component that protects the high-value strut assembly from damaging contamination. Using a genuine Piper OEM part ensures that the seal has the correct material properties and a precisely molded wiping edge to perform this critical function effectively. For a flight-critical system like the landing gear, there is no substitute for the certified performance and quality of genuine OEM parts.

Order Your 494-721 Wiper Seals Now

Protect your aircraft's landing gear and ensure long-term reliability with genuine Piper OEM components. Visit Airparts.aero to order your 494-721 wiper seals today.

The 494-721 wiper seal is the outer-most element in a typical landing gear strut's sealing system. It functions purely as a mechanical scraper. As the strut compresses upon landing, the chrome piston is exposed to the environment. Upon retraction, the sharp, slightly undersized lip of the 494-721 wiper makes firm contact with the chrome surface, physically scraping off any adhered dirt, ice, or grime. This ensures that a clean piston rod then passes through to the primary hydraulic seal, which is designed only to hold pressure, not to resist abrasion. Without an effective wiper seal, the primary seal would be quickly destroyed by contaminants, leading to a complete loss of fluid and nitrogen pressure and a collapsed "flat" strut.

Note: This is a flight-critical landing gear component. Installation must be performed by a certified A&P mechanic, typically during a strut reseal or overhaul, in strict accordance with the current Piper maintenance manual. Care must be taken not to damage the wiping lip during installation.