PA-14 Family Cruiser — Piper Aircraft PA-14 Family Cruiser

This Service Memo No. 4 provides critical information regarding the brake and oleo strut system fluid usage for various Piper aircraft, including the Piper PA-14 Family Cruiser. It outlines the types of brake fluids compatible with different models and emphasizes the importance of using the correct fluid to avoid damage to the brake expander tubes. The memo also includes identification markings for fluid compatibility and recommendations for maintenance practices. This document is essential for maintenance personnel and pilots to ensure the safe operation of the aircraft's braking system.

• Use Lockheed #21 fluid (blue) for pre-1942 models with brakes; Univis #40 fluid (red or amber) for models from 1942 onwards.
• Identification markings on expander tubes are crucial: red for mineral/petroleum fluids, blue for vegetable fluids.
• Unmarked tubes should be treated as compatible with Lockheed #21 fluid to avoid damage.
• Master cylinders may have synthetic rubber cups requiring Univis #40 fluid; ensure compatibility before use.
• Using the wrong fluid can damage brake expander tubes, leading to safety hazards.