Aircraft Maintenance and Safety Procedures

Bearing Maintenance and Inspection

To service a bearing, clean it with solvent and dry it with compressed air; however, never spin it with air or use steam to prevent severe damage. Next, inspect it for defects such as:

• Galling: Welded friction
• Spalling: Chipped metal
• Overheating: Bluish color
• Brinelling: Impact dents
• Bruising: Dirt damage
• Corrosion

Finally, wear protective gloves and lubricate the bearing with the manufacturer's recommended grease, applying it manually or using a pressure packer tool.

Cable System Inspection Protocols

During routine inspections, check cables for wear, corrosion, and broken wires. You must replace the cable if external wires blend together or if there are broken wires in critical fatigue areas where it passes over pulleys or fairleads. To check for internal wear, separate the strands. Additionally, inspect pulleys for:

• Smooth rotation
• Removal of dirt and flat spots
• Proper alignment to prevent the cable from rubbing the flanges

For pulleys that only move in small arcs, rotate them to provide a new bearing surface.

Safe Aircraft Defueling Procedures

Always consult the Maintenance Manual before defueling. You can remove fuel using the gravity method or the pumping method, making sure not to damage the tanks or mix the removed fuel with fresh fuel. For safety, you must:

• Ground both the aircraft and the defueling equipment.
• Turn off all electrical systems to prevent sparks.
• Have a fire extinguisher ready.
• Wear eye protection.

Deicing and Anti-icing Fluid Standards

Deicing fluids must be approved for holdover time, aerodynamic performance, and material compatibility. The standard fluid colors are:

• Base Glycol: Colorless
• Type I: Orange
• Type II: White/pale yellow
• Type III: Undetermined
• Type IV: Green

Use de-icing to remove existing ice from contaminated surfaces and anti-icing to protect against freezing precipitation. The application can be a 1-step or 2-step procedure depending on weather conditions, available equipment, fluid types, and the time remaining before departure.

Aviation Fueling Hazards and Static Risks

The main fire hazard of aviation fuel comes from its highly volatile vapors, as liquid fuel itself does not burn. Additionally, static electricity is a major hazard caused by friction. This static builds up both from the fuel flowing through the hoses and from the aircraft flying through the air, making proper grounding absolutely mandatory before any fueling operation.

Grounding and Bonding Safety Procedures

Grounding and bonding are safety procedures used to prevent static electricity sparks during fueling. Grounding connects the aircraft and fuel truck to the earth to provide a path for static electricity to disperse. Bonding uses a wire to connect the fuel truck directly to the aircraft to equalize their electrical charges. While many agencies now only use bonding, you must follow a critical precaution: never connect the bonding wire to painted or highly polished surfaces, because paint acts as an electrical insulator.

Aircraft Jacking and Structural Safety

When jacking an aircraft, always follow the manufacturer's manual because mistakes are highly dangerous and expensive. Before lifting, the aircraft must be in the proper configuration, which means closing specific doors and installing specific panels. This step is critical to provide structural strength and prevent structural damage while the aircraft is supported. Finally, consult the manual to locate the correct jacking points, as most aircraft require three or four jacks to be lifted safely.

Non-Destructive Inspection and Testing

Non-Destructive Testing (NDT) uses methods like the borescope, a visual inspection tool that allows you to see inside inaccessible areas—such as checking engine cylinders through spark plug holes for damage—without disassembling the components. Another essential method is Liquid Penetrant Inspection, which is used strictly to detect surface-open defects like fatigue cracks and porosity. It is critical to remember that liquid penetrants can only be applied to non-porous materials, such as metals, plastics, and glass.

Spring Inspection and Strength Testing

Springs are primarily vulnerable to corrosion and overheating. Corrosion combined with fatigue causes a severe loss of strength, while overheating ruins the metal's temper and mechanical properties. During a visual inspection, check for rust, blisters, or color changes, and reject the spring immediately if it shows signs of overheating. To test a spring, the most common method is measuring its unloaded static length to ensure it meets the manufacturer's tolerances. Alternatively, for critical springs, a load or deflection check is performed in a workshop to verify its correct strength under specific tension, compression, or torsion.

Aircraft Towing Safety and Protocols

Aircraft towing is a hazardous operation where large aircraft are moved using a tow tractor and towbar, while small ones can be pushed by hand on specific areas. The most critical safety rule is that a qualified person must always be inside the cockpit during towing to operate the brakes in case the towbar fails or disconnects.

Aircraft Riveting Standards and Installation

Aircraft riveting requires selecting the correct rivet size, with a diameter 2.5 to 3 times the thickest sheet (minimum 1/8 inch for structures) and an extra length of 1.5 diameters. Proper preparation is essential, keeping a minimum pitch of 3 diameters between rivets and an edge distance of 2 diameters, using deburred holes slightly larger than the rivet. Installation uses specific tools like bucking bars and Clecos to ensure a tight fit, and if a hole gets damaged, it must be reamed to install a larger rivet.