Summary of Aircraft Landing Gear and Brake Systems

## Introduction Proper landing gear and brake system knowledge is essential for safe aircraft ground operations, takeoffs, and landings. This guide explains inspection practices, basic components, tire care, shock strut maintenance, and brake system functions. It breaks down each topic into clear sections, practical examples, and quick-reference tables. > **Definition:** Landing gear comprises the wheels, shock absorbers, steering, and retraction systems that support an aircraft on the ground; the brake system converts hydraulic or mechanical input into stopping force. ## Landing Gear Inspections and Maintenance ### When to perform retraction checks - Accomplish landing gear retraction checks: 1. During annual and other scheduled type inspections 2. After replacing landing gear components 3. After any hard landing Practical example: After a hard landing in a crosswind that caused heavy rebound, schedule a retraction check before the next flight. ### Shock strut inflation (oleo-type) - Inflate oleo shock struts with a high-pressure source of **dry air or nitrogen**. Moisture in the inflation medium can cause corrosion or aeration of hydraulic fluid. Did you know that using nitrogen reduces internal condensation and oxidation compared with ambient air, extending strut life? > **Definition:** An oleo strut is a shock-absorbing landing gear component that uses compressed gas and hydraulic fluid to absorb landing energy. ### Care of shock struts - Inspect shock struts regularly for: - Fluid leakage - Proper extension (correct static extension length) - Scoring or corrosion on the exposed piston - Daily maintenance: wipe the exposed piston clean and inspect for damage Practical tip: Measure and record strut extension during preflight checks to spot gradual fluid leaks early. ## Tire Inflation and Tire Care ### Where to find tire inflation data - Tire inflation depends on: tire size, outside air temperature, and aircraft gross weight - Sources for specific pressures: - Operators Manual - Aircraft Maintenance Manual (AMM) - Special tire inflation pressure charts (often indexed by gross weight) ### Effects of under-inflation - Under-inflated tires are more likely to: - Creep or slip on the wheel during landing or heavy braking - Exhibit rapid or uneven wear near the tread edges Practical example: On a hot day, monitor tire pressure closely; temperature rise increases pressure but recommended inflation may already account for ambient conditions per the AMM. > **Definition:** Tire creep is the rotation of the tire relative to the wheel due to insufficient friction or inadequate clamping force, often caused by under-inflation. ## Wheel Construction (split-type wheel) - The rubber packing on the mating surface of the outer wheel half prevents air leakage in tubeless tire installations. Table: Split-type wheel component function | Component | Purpose | |---|---| | Outer wheel half rubber packing | Prevents tubeless tire air leakage | | Split-type wheel halves | Allow assembly/disassembly around axle without removing brake assemblies | Did you know that many modern transport-category aircraft use tubeless tires to simplify maintenance and speed tire changes? ## Brake Systems: Types and Components ### Three basic brake actuating systems - **Independent system**: Each wheel/brake is actuated independently; typically used on small aircraft - **Booster system**: Uses mechanical or hydraulic boosters to increase pilot force input effectiveness - **Power brake system**: Uses an external power source (e.g., hydraulic power) to provide braking force Table: Brake system comparison | System | Typical use | Key characteristic | |---|---:|---| | Independent | Small aircraft | Direct pedal-to-wheel actuation | | Booster | Medium aircraft | Amplifies pilot force for lighter pedal feel | | Power brake | Larger aircraft | Uses system pressure to apply brakes with high force | ### Debooster purpose - The **debo