AMT 641: Aircraft Ground Operations and Servicing Study Notes

North Manila WCC Aeronautical & Technological College emphasizes cleanliness and orderliness as essential for safe aircraft maintenance and accident prevention.
Work Area Management: Tools must be stored after shifts; outgoing personnel are responsible for toolboxes, maintenance stands, hoses, and electrical cords.
Safety Lanes: Identify painted Pedestrian Walkways and Fire Lanes to prevent collisions and keep traffic out of active work areas.
Warning symbols and Material Safety Diamonds (NFPA 704) identify hazards (Health, Flammability, Instability, Special) and required Personal Protective Equipment (PPE).
Safety Data Sheets (SDS), required by OSHA, provide detailed chemical composition, health hazards, and emergency procedures.

Physiological Hazards: Electricity causes damage to the nervous system, severe burns, permanent injury, or death.
Safety Factors: Fear, overconfidence, and lack of knowledge increase electrical accident risks.
Fire Prevention: Electrical current generates heat; surplus heat from short circuits or damaged insulation can ignite flammable substances.
Handling: Wires should never be placed where they can be crushed; broken strands increase current load in remaining wires.

Drill Press: Requires eye protection, clamped work, and correct $RPM$ settings.
Lathe: Sharp cutting tools are necessary; never stop the chuck by hand.
Grinder: Avoid side pressure to prevent wheel explosion; do not stand in line with the rotating wheel.
Milling Machine: Ensure clamps clear the arbor and do not change feed speed during operation.
Welding on Aircraft: Prohibited within $25\,ft$ of other aircraft or open fuel tanks; requires a trained fire watch, a tug attached for emergency towing, and a fire extinguisher with a minimum $20B$ rating.

Preparation: Position aircraft headed into the prevailing wind; lock nosewheels or tailwheels in the fore-and-aft position.
Land Planes: Use specific tie-down rings; Manila rope requires about $1\,inch$ of slack because it shrinks when wet. Use anti-slip knots like the bowline.
Heavy Aircraft: Utilize control surface locks and battens for high winds; acceptable materials include $\frac{1}{4}-inch$ wire cable or $1\frac{1}{2}-inch$ manila rope.
Seaplanes: Secured to buoys or docks; in storms, compartments may be flooded or floats filled with water to increase stability.
Ski Planes: Use a dead-man device (buried object in a snow/ice trench) when anchors are unavailable.
Helicopters: Secured to withstand winds up to $65\,mph$ ; align and tie down rotor blades using tip socks and straps.
Weight-Shift-Control: Highly susceptible to wind; require lowering the wing close to the ground in high winds.

Hearing Protection: External earmuffs or internal earplugs are required for loud tools and engine noise to prevent permanent loss.
FOD Prevention: Conduct routine "FOD Walks" to remove debris; follow strict tool control programs.
Engine Hazards: Turbine intake suction points and high-speed exhaust zones; never approach a helicopter from the rear due to tail rotor danger.
Ground Support Equipment (GSE): Maintain safe distances and ensure equipment is properly stowed to prevent rolling.

General: Fireguard must have a minimum $5\,lb$ $CO_2$ extinguisher and remain in the pilot’s line of sight.
Reciprocating Engines: - Check radial engines for hydraulic lock if inactive for over $30\,minutes$ by turning the prop $3-4$ revolutions. - Hand Cranking: Requires a Propeller Operator and Engine Operator; the callout "Contact" must precede turning the ignition $ON$ . - Max cranking limit: $1\,minute$ followed by $3-5\,minutes$ of cooling. - Oil pressure must appear within $30\,seconds$ of start.
Turbine Engines (Turboprop/Turbofan): - Monitor Inter-Turbine Temperature (ITT) or Exhaust Gas Temperature (EGT). - Hot Start: Excessively rich mixture causes $EGT$ to exceed limits; shut off fuel immediately. - Hung (False) Start: Insufficient starter power causes the engine to fail to reach self-sustaining speed. - Auxiliary Power Units (APU): Small turbine engines providing ground electrical power and starting air.

Towing: Team includes Driver, Wing Walkers, Tail Walker, and Cockpit Personnel (to operate brakes). Torsion loads on tow bars must be avoided.
Taxiing: Movement performed by rated pilots or qualified technicians; a signalman provides precise hand signals (illuminated wands at night).
Night Signal: Crossing wands in an "X" above the head indicates an emergency stop.

Oil: Checked via dipstick or sight gauge; check turbine engines immediately after shutdown, but check reciprocating engines after they are inactive.
Hydraulic Systems: Ground Power Units (HPUs) can deliver up to $3000\,psi$ ; high pressure can cause skin penetration injuries.
Electrical Power: Ground Power Units (GPUs) can be stationary, towed, or self-propelled; supplying $DC$ or $400\,Hz$ $AC$ power.
Oxygen: Two-person rule is mandatory; hazards include fire intensification and frostbite from Liquid Oxygen (LOX) at $-297\,F$ ( $-183\,C$ ). - Commercial Types: Aviators Breathing Oxygen (ABO), Industrial, and Medical.
Fuel Types: - AVGAS (Piston): $80/87$ (Red), $100/130$ (Green), $100LL$ (Blue), $115/145$ (Purple). - Jet Fuel (Turbine): Jet A/A-1 (Kerosene-based) and Jet B (Kerosene/Gasoline mix).