Safety, Ground Operations, & Servicing

Question 1

Shop Safety

Answer 1

• Keeping the shop, hangars, and flight line clean is essential to safety and efficient maintenance
• Safety is everyone’s business. However, technicians and supervisors must watch for their own safety
• Signs are posted to indicate dangerous equipment or hazardous conditions
• Additionally, there are signs that provide the location of first aid and fire equipment.
• Safety lanes, pedestrian walkways, and fire lanes are painted around the perimeter inside the hangars.
• This is a safety measure to prevent accidents and to keep pedestrian traffic out of work areas.
• Communication is key to ensuring everyone’s safety

Question 2

Electrical Safety

Answer 2

• Working with electrical equipment poses certain physiological safety hazards
  severe burns inside & outside
• the nervous system is affected and can be damaged or destroyed
• Wearing proper safety equipment provide a psychological assurance and physically protection
• rubber gloves, safety glasses,rubber or grounded safety mats, and other safety equipment

Question 3

Physiological Safety

Answer 3

Two factors that affect safety fear and overconfidence

Question 4

Fire Safety

Answer 4

• To preventing electrical fires keep area around electrical work or electrical equipment clean, uncluttered, and free of all unnecessary flammable substances
• Ensure that all power cords, wires, and lines are free of kinks and bends that can damage the wire
  .
• Neverplace wires or cords where they may be walked on or runover by other equipment
• Monitor the condition of electrical equipment repair or replace damaged equipment before further use

Question 5

Safety Around Compressed Gases

Answer 5

• Inspect air hoses frequently for breaks and worn spots. Unsafe hoses must be replaced immediately
• Keep all connections in a “no-leak condition.”
• Maintain in-line oilers, if installed, in operating condition
• Ensure the system has water sumps installed and drained at regular intervals
• Filter air used for paint spraying to remove oil and water
• Never use compressed air to clean hands or clothing. Pressure can force debris into the flesh leading to infection
• Never spray compressed air in the area of other personal
• Straighten, coil, and properly store air hoses when not in use.
• Many accidents involving compressed gasses occur during aircraft tire mounting.
• To prevent possible personal injury, use tire dollies and other appropriate devices to mount or remove heavy aircraft tires.
• always use tire cage guards when inflating tires
• Use pressure regulators on high-pressure air bottles to eliminate the possibility of over inflation of tires

Question 6

Safety Around Hazardous Materials

Answer 6

four-color segmented diamond that represents
- flammability (red),
- reactivity (yellow)
- health (blue)
- special hazard (white)

there is a number from 0 to 4 little or no hazard to very hazardous
- RAD for radiation,
- ALK for alkali materials
- Acid for acidic materials
- CARC for carcinogenic materials W high reactivity to water
- SDS Safety data sheet
- MSDS Material safety data sheet
- OSHA U.S. Department of Labor Occupational Safety and Health Administration

Question 7

Drill press

Answer 7

drill press can be used to bore and ream holes

● Wear eye protection.
● Securely clamp all work.
● Set the proper revolutions per minute (rpm) for the material used
● Do not allow the spindle to feed beyond its limit of travel while drilling.
● Stop the machine before adjusting work or attempting to remove jammed work.
● Clean the area when finished.

Question 8

Lathes

Answer 8

Lathes are used in turning work of a cylindrical nature inside or outside of the cylinder

● Wear eye protection.
● Use sharp cutting tools.
● Allow the chuck to stop on its own. Do not attempt to stop the chuck by hand pressure.
● Examine tools and work for cracks or defects before starting the work.
● Do not set tools on the lathe. Tools may be caught by the work and thrown.
● Before measuring the work, allow it to stop in the lathe.

Question 9

Milling machine

Answer 9

Milling machines are used to shape or dress; cut gear teeth, slots, or key ways

● Wear eye protection.
● Clean the work bed prior to work.
● Secure the work to the bed to prevent movement during milling
● Select the proper tools for the job.
● Do not change the feed speed while working.
● Lower the table before moving under or away from the work
● Ensure all clamps and bolts are passable under the arbor

Question 10

Grinder

Answer 10

Grinders are used to sharpen tools, dress metal, and perform other operations involving the removal of small amounts of metal

● Wear eye protection, even if the grinder has a shield.
● Inspect the grinding wheel for defects prior to use.
● Do not force grinding wheels onto the spindle. They fit snugly but do not require force to install them. Placing side pressure on a wheel could cause it to explode.
● Check the wheel flanges and compression washer They should be one-third the diameter of the wheel.
● Do not stand in the arc of the grinding wheel while operating in case the wheel explodes.

Question 11

Welding

Answer 11

Welding must be performed only in designated areas (welding shop) Any part that is to be welded must be removed from the aircraft, if possible
.
A welding shop must be equipped with proper tables, ventilation, tool storage, and
fire prevention and extinguishing equipment

● During welding operations, open fuel tanks and work on fuel systems are not permitted.
● Painting is not permitted.
● No aircraft are to be within 35 feet of the welding operation
● No flammable material is permitted in the area around the welding operation
● Only qualified welders are permitted to do the work
● The welding area is to be roped off and placarded
● Fire extinguishing equipment of a minimum rating of 20B must be in the immediate area with 80B rated equipment as a backup
● Trained fire watches are to be present in the area around the welding operation
● The aircraft being welded must be in a towable condition, with a tug attached, and the aircraft parking brakes released. A qualified operator must be on the tug and mechanics available to assist in the towing operation should it become necessary to tow the aircraft. If the aircraft is in the hangar, the hangar doors are to be open.

Question 12

Flight Line Safety

Answer 12

• The flight line is a place of dangerous activity
• Technicians who perform maintenance on the flight line must constantly be aware of what is going on around them

Question 13

Hearing Protection

Answer 13

Hearing Protection

● external earmuffs or headphones
● internal type fits into the auditory canal

Question 14

Foreign Object Damage (FOD)

Answer 14

● Any damage to aircraft, personnel, or equipment caused by any loose object

Question 15

Safety Around Airplanes

Answer 15

● aware of propellers
● Stay in pilot view
● Turbine engine intakes and exhaust
● Don’t smoke or open flames
● Aircraft fluid can harm skin
● When operating support equipment have space between aircraft and equipment
secured
● All items stowed properly

Question 16

Safety Around Helicopters

Answer 16

When approaching a helicopter while the blades are turning, adhere to the following guidelines to ensure safety

● Observe the rotor head and blades to see if they are level. This allows maximum clearance when approaching the helicopter.

● Approach the helicopter in view of the pilot.

● Never approach a helicopter carrying anything with a vertical height that the blades could hit. This could cause blade damage and injury to the individual.

● Never approach a single-rotor helicopter from the rear. The tail rotor is invisible when operating.

● Never go from one side of the helicopter to the other by going around the tail. Always go around the nose of the helicopter.

● When securing the rotor on helicopters with elastomeric bearings, check the maintenance manual for the proper method. Using the wrong method could damage the bearing

Question 17

Fire Safety

Answer 17

The key to fire safety is knowledge of what causes a fire, how to prevent it, and how to put it out

Question 18

Requirements for Fire to Occur

Answer 18

1. Fuel
2. Friction (Heat)
3. Oxygen

Question 19

Classification of Fires

Answer 19

National Fire Protection Association (NFPA) Class A, Class B, and Class C.

1. Class A fires involve ordinary combustible materials, such as wood, cloth, paper, upholstery materials, and so forth.
2. Class B fires involve flammable petroleum products or other flammable or combustible liquids, greases, solvents, paints, and so forth.
3. Class C fires involve energized electrical wiring and equipment.

4.the Class D fire, involves flammable metal. Class D fires are not commercially considered by the NFPA involves magnesium

Question 20

Fire Extinguishers

Answer 20

• Water class A
• Carbon dioxide (CO2) class A,B & C
• Dry powder D also B,C
• Halogenated hydrocarbon B,C & A,D but less effective

Question 21

Inspection of Fire Extinguishers

Answer 21

• Proper location of appropriate extinguisher
• Safety seals unbroken
• All external dirt and rust removed
• Gauge or indicator in operable range
• Proper weight
• No nozzle obstruction
• No obvious damage

Question 22

Identifying Fire Extinguishers

Answer 22

• Fire extinguishers are marked to indicate suitability for a particular class of fire by decals or paint large enough
• must be placed on the fire extinguisher and in a conspicuous place on the fire extinguisher

Question 23

Using Fire Extinguishers

Answer 23

● When using a fire extinguisher, ensure the correct type is used for the fire
● Most extinguishers have a pin to pull that allows the handle to activate the agent
● Stand back 8 feet
● aim at the base of the fire
● Squeeze the lever and sweep side to side until the fire is extinguished

Question 24

Preparation of Aircraft

Answer 24

● Aircraft are to be tied down after each flight to prevent damage from sudden storms
● The direction that aircraft are to be parked and tied down is determined by prevailing or forecast wind direction
● Aircraft are to be headed into the wind, depending on the locations of the parking area’s fixed tie-down points
● Spacing of tie-downs need to allow for ample wingtip clearance
● After the aircraft is properly located, lock the nosewheel or the tail wheel in the fore-and-aft position.

Question 25

Securing Light Aircraft

Answer 25

• Light aircraft are typically secured with ropes tied only at provided tie-down rings.
• Never tie ropes to lift struts to prevent potential damage.
• Provide about 1 inch of slack in manila ropes for movement, as they shrink when wet.
• Too much slack can cause jerking against the ropes, while tight ropes can put stress on
  the aircraft not designed for such loads.
• Knots and Securing Methods
• The effectiveness of tie-down ropes depends on the knot used.
• Anti-slip knots like the bowline are recommended for quick tying and easy untying.
• Aircraft without Tie-Down Fittings
• Aircraft without tie-down fittings must be secured according to the manufacturer’s
  instructions.
• Ropes should be tied to outer ends of struts on high-wing monoplanes, or suitable rings provided where permitted structurally.

Question 26

Securing Heavy Aircraft

Answer 26

• Tie-Down Procedure for Heavy Aircraft
• Rope or cable tie-downs are typically used.
• Number of tie-downs depends on anticipated weather conditions.
• Most heavy aircraft have surface control locks engaged when secured.
• Different aircraft may have varied control locking methods, so refer to manufacturer’s instructions.
• Control surface battens can be installed in high winds to prevent damage. - Common tie-down points are illustrated in Figure 1-11.
• Normal Tie-Down Procedure
  1. Position aircraft into prevailing wind whenever possible.
  2. Install control locks, covers, and guards.
  3. Chock all wheels fore and aft (refer to Figure 1-12).
  4. Attach tie-down reels to aircraft tie-down loops, anchors, or stakes. Use stakes for
  temporary tie-down. If reels aren’t available, use 1/4” wire cable or 1.5” manila line

Question 27

Tie-Down Procedures for Seaplanes

Answer 27

• Seaplanes can be moored to a buoy, weather permitting, or tied to a dock
  Weather causes wave action, and waves cause the seaplane to bob and roll
• This bobbing and rolling while tied to a dock can cause damage
• When a storm fill the floats with water and tying and remove from water and put on land

Question 28

Tie-Down Procedures for Ski Planes

Answer 28

• Ski planes are tied down same as land planes
• Ski-equipped airplanes can be secured on ice or in snow by using a device called dead-man
• A dead-man is any item at hand, such as a piece of pipe, log, and so forth, that a rope is attached to and buried in a snow or ice trench
• Using caution to keep the free end of the rope dry and unfrozen, snow is packed in the trench.
• If available, pour water into the trench; when it is frozen, tie down the aircraft with the free end of the rope.
• pack soft snow around the skis, pour water on the snow, and permit the skis to freeze to the ice this is in addition of the tigh down this is for windstorms

Question 29

Tie-Down Procedures for Helicopters

Answer 29

1. Position Helicopter:
   - Face the helicopter in the direction of the highest anticipated winds or gusts
2. Spotting Distance
   - Place the helicopter slightly more than one rotor span away from other aircraft
3. Wheel and Skid Securing
   - For wheeled helicopters: Place chocks in front of and behind all wheels.
   - For skid-equipped helicopters: Retract ground handling wheels, lower to rest on skids, install lock pins or remove handling wheels, and store them securely.
4. Blade and Tie-Down Securing
   - Align blades and install tie-down assemblies as per manufacturer’s instructions.
   - Tie straps snugly, allowing slack in wet weather to prevent stress from strap shrinkage.
5. Tie-Down Ropes/Cables
   - Fasten to the forward and aft landing gear cross tubes and secure to ground stakes or tie-down rings.

Question 30

Procedures for Securing Weight-Shift-Control

Answer 30

• weight-shift-controlled aircraft— engine powered and non-powered.
• These types of aircraft are very susceptible to wind damage
• The wings can be secured in a similar manner as a conventional aircraft in light winds.
• In high winds, the mast can be disconnected from the wing and the wing placed close to the ground and secured
• This type of aircraft can also be partially disassembled or moved into a hangar for protection

Question 31

Procedures for Securing Powered Parachutes

Answer 31

1. Pack the Parachute
   - Place the parachute in a bag to prevent it from filling with air and dragging the seat and engine
2. Secure the Engine and Seat
   - If necessary, additionally secure the engine and seat to prevent movement.

Question 32

Engine Starting and Operation

Answer 32

1. Position the Aircraft
   - Head the aircraft into the prevailing wind for adequate engine cooling.
2. Ensure Safety
   - Prevent property damage or personal injury from propeller blast or jet exhaust.
3. External Electrical Power
   - Verify it can be removed safely and is sufficient for the entire starting sequence.
4. Fireguard Presence
   - Station a fireguard with a suitable fire extinguisher (at least 5-pound CO2) next to the engine, visible to the pilot, to monitor for starting problems.
5. Clear Turbine-Engine Area
   - Keep the area in front of the jet inlet clear of personnel, property, and debris.
6. General Application
   - Apply these procedures to all aircraft powerplants.
7. Follow Manufacturer’s Checklists
   - Adhere to specific start and shutdown procedures provided by the aircraft manufacturer

Question 33

Steps for starting a radial engine

Answer 33

1. Check Ignition Switch
   - Ensure the ignition switch is off if the engine has been shut down for more than 30
   minutes.
2. Turn Propeller by Hand
   - Rotate the propeller three or four complete revolutions to detect a hydraulic lock.
3. Detecting Hydraulic Lock
   - Look for abnormal effort required to rotate the propeller or abrupt stopping during
   rotation.
4. Avoid Force
   - Do not use force to turn the propeller if a hydraulic lock is detected to prevent damage
5. Clear Hydraulic Lock
   - Remove the front or rear spark plug from the lower cylinders.
   - Pull the propeller through to clear the lock.
6. Proper Direction
   - Always pull the propeller through in the normal rotation direction to avoid injecting liquid into the intake pipe and causing further lock issues.

Question 34

steps for starting an aircraft engine, including fuel and ignition procedures

Answer 34

1. Turn on the Auxiliary Fuel Pump (if equipped).
2. Set the Mixture Control
   - For fuel injection: “idle cut-off” position.
   - For float-type carburetors: “full rich” position.
   - Adjust the mixture as needed if using a pull rod control.
3. Open the Throttle
   - Set to provide 1,000 to 1,200 rpm (approximately 1/8” to 1/2” from “closed” position).
4. Set Preheat/Alternate Air Control
   - Leave in the “cold” position to prevent damage or fire in case of backfire.
5. Prime the Engine
   - Use the primer switch or priming pump (1-3 strokes, more in colder weather).
6. Energize the Starter
   - Allow the propeller to make at least two revolutions, then turn the ignition switch on.
   - For engines with an induction vibrator: turn the switch to “both” and energize starter.
   - For impulse coupling magneto engines: turn ignition switch to “left” and starter to “start.” - Do not crank the engine for more than 1 minute at a time, allow 3-5 minutes for cooling
   between attempts.
7. Adjust Mixture After Starting
   - Move mixture control to “full rich” if initially in “idle cut-off” position. - Ensure carbureted engines are in the rich mixture position.
   - Check oil pressure.
8. Monitor Engine Instruments
   - Use tachometer (rpm), manifold pressure gauge, oil pressure gauge, oil temperature
   gauge, cylinder head temperature gauge, and exhaust gas gauge to monitor the engine

Question 35

Hand Cranking Engines

Answer 35

1. Initial Preparations
   - Verify that the aircraft has no self-starter.
   - Ensure the ground is firm and free of slippery grass, mud, grease, or loose gravel.
2. Coordinate with the Operator
   - The person turning the propeller calls: “Fuel on, switch off, throttle closed, brakes on.” - The person operating the engine checks these items and repeats the phrase.
   - Ensure the switch and throttle are not touched until further instructions.
3. Prepare for Hand Propping
   - Stand close enough to the propeller to step away as it is pulled down. - Do not stand in a position that requires leaning toward the propeller.
4. Hand Propping Procedure
   - The person swinging the prop calls “contact.”
   - The operator repeats “contact” and then turns on the switch. - Never turn on the switch before calling “contact.”
5. Safety Precautions
   - Always assume the ignition is on while touching the propeller.
   - Be aware that a faulty switch can still permit current flow even if in the “off” position. - Avoid any part of the body getting in the propeller’s way.
6. Starting the Engine
   - Move the propeller blade downward by pushing with the palms of the hands. - Do not grip the blade with fingers curled over the edge to avoid “kickback.”
7. Throttle Management
   - Gradually open the throttle while the engine is cold to reduce backfiring. - Avoid over-priming the engine before it is turned over by the starter.
8. Handling Engine Flooding
   - If the engine is flooded, turn the ignition switch off and move the throttle to “full open.” - Turn the engine over by hand or by the starter to rid excess fuel.
   - Stop immediately if excessive force is needed to turn over the engine.
   - If necessary, remove the lower cylinder spark plugs.
9. Post-Start Procedures
   - Immediately check the oil pressure indicator after the engine starts.
   - If no oil pressure is indicated within 30 seconds, stop the engine and determine the issue. - If oil pressure is indicated, adjust the throttle to the manufacturer’s specified rpm for warm-up (usually between 1,000 to 1,300 rpm).
10. Engine Cooling and Monitoring
    - Operate the engine with the propeller in full low pitch and headed into the wind with the cowling installed.
    - Closely monitor engine instruments at all times. - Keep cowl flaps open during ground operations.

• Ensure no personnel, ground equipment, or other aircraft are in the propeller wash during warm-up.

Question 36

Extinguishing Engine Fires

Answer 36

1. Assign a Fireguard
   - Designate a person as a fireguard equipped with a CO2 fire extinguisher.
2. Fireguard Responsibilities
   - Ensure the fireguard understands the engine’s induction system. - Direct CO2 into the air intake if a fire occurs during starting.
3. Potential Fire Sources
   - Be aware that fires can occur in the exhaust system from ignited fuel expelled during engine rotation.
4. Handling an Engine Fire
   - If a fire develops during starting, continue cranking to start the engine and extinguish the fire
   - If the engine fails to start and the fire persists, discontinue the start attempt.
5. Fire Extinguishing
   - If necessary, the fireguard extinguishes the fire using available equipment
6. Safety Observance
   - Maintain strict adherence to safety practices while standing by during the starting
   procedure.

Question 37

Turbine engine

Answer 37

1. Starting Sequence
   - The starter turns the main compressor to provide airflow.
   - Igniters are activated to spark fuel ignition at the correct airflow speed. - As the engine accelerates, the starter disengages
2. Pre-Start Inspection
   - Remove aircraft covers and inspect exhaust areas for fuel or oil.
   - Visually inspect accessible engine parts and controls.
   - Check nacelle areas for secured inspection plates, sumps for water, and air inlets for
   foreign objects.
   - Check compressor rotation if possible
3. Starting Procedures
   - Turboprop engine starting procedures vary widely; refer to manufacturer instructions for
   specific procedures.
   - Turboprop engines can be fixed turbine or free turbine.
   - Fixed turbine engines directly turn the propeller during start, while free turbine engines keep the propeller in the feather position until the gas generator accelerates.
   - Instruments include oil pressure, temperature, inter-turbine temperature, fuel flow, gas generator speed, propeller speed, and torque.
   - Turbine engines require adequate power for the starter; smaller engines use electric motors, while larger engines use air turbine starters.
4. Air Source for Starter
   - Air turbine starters can be powered by an onboard APU, external source, engine
   cross-bleed, or low-pressure tank.
   - Smaller turboprop engines may use a starter/generator combination for starting.
   While starting an engine, always observe the following:
   ● Always observe the starter duty cycle. Otherwise, the starter can overheat and be damaged.
   ● Assure that there is enough air pressure or electrical capacity before attempting a start.
   ● Do not perform a ground start if turbine inlet temperature (residual temperature) is above that specified by the manufacturer.
   ● Provide fuel under low pressure to the engine’s fuel pump.

Question 38

To start an engine on the ground, perform the following operations

Answer 38

1. Turn the aircraft boost pumps on
2. Make sure that the power lever is in the “start” position
3. Place the start switch in the “start” position. This starts the engine turning
4. Place the ignition switch on. (On some engines, the ignition is activated by moving the fuel lever.)
5. The fuel is now turned on. This is accomplished bymoving the condition lever to the “on” position.
6. Monitor the engine lights of the exhaust temperature. If it exceeds the limits, shut the engine down.
7. Check the oil pressure and temperature.
8. After the engine reaches a self-sustaining speed, the starter is disengaged.
9. The engine continues to accelerate up to idle.
10. Maintain the power lever at the “start” position until the specified minimum oil temperature is reached.
11. Disconnect the ground power supply, if used
    If any of the following conditions occur during the starting turn off the fuel and ignition switch, discontinue the start immediately, make an investigation, and record the findings.
    ● Turbine inlet temperature exceeds the specified maximum. Record the observed peak temperature.
    ● Acceleration time from start of propeller rotation to stabilized rpm exceeds the specified time.
    ● There is no oil pressure indication at 5,000 rpm for either the reduction gear or the power unit.
    ● Torching (visible burning in the exhaust nozzle).
    ● The engine fails to ignite by 4,500 rpm or maximum motoring rpm.
    ● Abnormal vibration is noted or compressor surge occurs (indicated by backfiring).
    ● Fire warning bell rings. (This may be due to either an engine fire or overheat.)

Question 39

Turbofan Engines

Answer 39

• Preflight Run-Up
• Unlike reciprocating engine aircraft, turbine-powered aircraft typically don’t require a preflight run-up unless investigating a suspected malfunction.
• Pre-Starting Preparations
• Remove all protective covers and air inlet duct covers before starting.
• Ideally, position the aircraft into the wind for better cooling, faster starting, and smoother engine performance, especially if engine trimming is necessary.
• Clearing the Run-Up Area
• Ensure the area around the aircraft is clear of personnel and loose equipment.
• Take caution to clear the run-up area of any debris, as turbine engine air inlets can be hazardous
• Fuel and Engine Inspection
• Check aircraft fuel sumps for water or ice.
• Inspect the engine air inlet for foreign objects and general condition.
• Visually inspect fan blades, compressor blades, and compressor inlet guide vanes for damage.
• If possible, check fan blades for free rotation by hand.
• Ensure all engine controls are operational and check engine instruments and warning lights for proper operation.

Question 40

Starting a Turbofan Engine

Answer 40

• Starting Procedure Overview
• Starting procedures for turbofan engines vary widely.
• Detailed starting procedures should be followed according to the manufacturer’s
  instructions.
• Starting Equipment
• Turbofan engines can be started using either air turbine or electrical starters.
• Air-turbine starters use compressed air from an external source.
• Fuel is turned on by moving the start lever to the “idle/start” position or opening a fuel shutoff valve.
• Starting Sequence
• With an air turbine starter, the engine should “light off” within a predetermined time after
  fuel is turned on.
• Most turbofan engine controls include power levers, reversing levers, and start levers or
  fuel switches.
• Instruments measure various parameters such as engine speed, exhaust gas
  temperature, fuel flow, oil pressure, temperature, and engine pressure ratio, which measures thrust delivery.

1. If the engine is so equipped, place the power lever in the “idle” position
2. Turn the fuel boost pump(s) switch on
3. A fuel inlet pressure indicator reading ensures fuel is being delivered to engine fuel pump inlet
4. Turn engine starter switch on. Note that the engine rotates to a preset limit. Check for oil pressure
5. Turn the ignition switch on. (This is usually accomplished by moving the start lever toward the “on” position A micro switch connected to the leveler turns on the ignition.)
6. Move the start lever to “idle” or “start” position, this starts fuel flow into the engine 7. Engine start (light off) is indicated by a rise in exhaust gas temperature
7. If a two-spool engine, check rotation of fan or N1
8. Check for proper oil pressure
9. Turn engine starter switch off at proper speeds
10. After engine stabilizes at idle, ensure that none of the engine limits are exceeded 12. Newer aircraft drop off the starter automatically

Question 41

Auxiliary Power Units (APUs)

Answer 41

• APU Overview
• Auxiliary Power Units (APUs) are smaller turbine engines.
• They provide compressed air for starting engines, cabin heating and cooling, and
  electrical power while on the ground.
• Operation
• Starting the APU is typically simple: turn a switch to the start position, and the enginestarts automatically.
• Monitor exhaust gas temperature during start.
• APUs idle at 100 percent rpm with no load.
• Once operating rpm is reached, the APU can be used for cabin cooling or heating and for
  generating electrical power.
• APUs are commonly used to start the main engines.

Question 42

Hot Start

Answer 42

• A hot start happens when the engine starts, but the exhaust gas temperature surpasses specified limits.
• Typically caused by an overly rich air-fuel mixture in the combustion chamber. - This can result from either excessive fuel or insufficient airflow.
• Action Required
• Immediately shut off the fuel supply to the engine to prevent further issues.

Question 43

False or Hung Start

Answer 43

• False or hung starts occur when the engine starts normally, but the RPM remains at a low value instead of increasing to the normal starting RPM.
• Often caused by insufficient power to the starter or the starter cutting off prematurely before the engine starts self-accelerating.
• Action Required In this situation, the engine should be shut down.

Question 44

Engine Fails to Start

Answer 44

The engine failing to start within the prescribed time limit can result from various factors:
- Lack of fuel to the engine.
- Insufficient or no electrical power to the exciter in the ignition system. - Incorrect fuel mixture.
- Action Required If the engine fails to start within the prescribed time, it should be shut down.
- In all cases of unsatisfactory starts, the fuel and ignition must be turned off.
- Continue rotating the compressor for approximately 15 seconds to remove accumulated fuel from the engine.
- If unable to rotate the engine, allow a 30-second fuel draining period before attempting another start.

Question 45

Towing of Aircraft

Answer 45

• Large aircraft are towed using tow tractors, while smaller aircraft may be moved by hand pushing.
• Towing must be done cautiously to prevent damage and injury.
• Specific towing instructions are provided by the aircraft manufacturer and must be followed. - Before towing, a qualified person must be in the flight deck to operate brakes in case of a tow bar failure.
• Tow bars must be inspected for damage before use.
• Towing speed must be reasonable, and the person in the flight deck must coordinate braking with the towing vehicle.
• Attachment of tow bars varies depending on the aircraft’s landing gear configuration. - Towing procedures involve assigning wing walkers, ensuring brakes are charged, and following safe towing speeds.
• Aircraft are parked in designated areas with proper chocking and control locks.
• Prior to movement across runways or taxiways, clearance must be obtained from the airport control tower.
• Aircraft parked in hangars must be statically grounded immediately.

Question 46

Taxiing Aircraft

Answer 46

• Only rated pilots and qualified airframe and powerplant (A&P) technicians are authorized to start, run up, and taxi aircraft.
• Taxiing operations must comply with applicable local regulations.
• Control towers use standard taxi light signals to control and expedite aircraft taxiing.
• Detailed instructions on taxi signals and related taxi instructions are provided in the following section.

Question 47

Taxi Signals

Answer 47

Taxi Signals and Signalman Responsibilities
- Ground accidents often result from improper taxiing techniques.

• A taxi signalman can assist pilots, especially when the pilot’s vision is obstructed on the ground.
• The signalman’s standard position is slightly ahead of and in line with the aircraft’s left wingtip, ensuring visibility to the pilot.
• Standard aircraft taxiing signals are published in FAA publications like the Aeronautical Information Manual (AIM) and may vary depending on operational conditions.
• Signal execution should be clear and precise to avoid confusion, with over-exaggerated signals to ensure visibility.
• If there’s any doubt about a signal or if the pilot doesn’t seem to follow, the signalman should use the “stop” sign and restart the signals.
• The signalman should indicate the approximate parking area to the pilot and regularly glance behind to avoid hazards.
• Night taxi signals are given with illuminated wands attached to flashlights, with the “emergence stop” signal forming a lighted “X” above and in front of the head

Question 48

Servicing Aircraft Air/Nitrogen Oil & Fluids

Answer 48

• Checking or servicing aircraft fluids is crucial, and specific procedures should be followed as outlined in the aircraft maintenance manual.
• Aircraft engine oil levels are typically checked using a dipstick or sight gauge, with markings indicating the correct level.
• Reciprocating engines should be checked after inactivity, while turbine engines should be checked just after shutdown.
• Dry sump oil systems may hide oil in the gearcase, which doesn’t show on the dipstick until the engine is started.
• Overfilling the oil tank should be avoided, as oil foams when circulated through the engine.
• Hydraulic reservoirs require the correct fluid, which can often be determined by color or container markings. Contamination should be prevented during servicing.
• Pressurized reservoirs may require bleeding before servicing, and caution is necessary when changing hydraulic filters to avoid leaks.
• When servicing tires or struts with high-pressure nitrogen, technicians should clean areas before connecting filling hoses and avoid overinflating.

Question 49

Electric Ground Power Units

Answer 49

• Ground support electrical APUs come in various sizes and types, classified as towed, stationary, or self-propelled equipment
• Some units are designed for hangar use during maintenance, while others are used on the flight line, either stationary or towed between aircraft
• Stationary units can be powered from the facility’s electrical service, while movable units typically have an onboard engine driving a generator or use batteries
• Smaller units are high-capacity batteries for starting light aircraft, mounted on wheels or skids with long electrical lines and plug-in adapters
• Larger towed units feature generators, providing constant-current, variable voltage DC power for starting turbine aircraft engines and constant-voltage DC for reciprocating engines
• Self-propelled units offer a wider range of output voltages and frequencies but are usually more expensive
• Proper positioning of ground power units is essential to prevent collisions with aircraft or nearby objects in case of brake failure.
• When using these units, observe all electrical safety precautions, and never move a power unit when service cables are attached to an aircraft or when the generator system is engaged.

Question 50

Hydraulic Ground Power Units

Answer 50

• Portable hydraulic test stands are available in various sizes and price ranges, with some offering a limited range of operation and others capable of performing all
  system tests like fixed-shop test stands.
• Hydraulic power units, also known as hydraulic mules, supply hydraulic pressure to operate aircraft systems during maintenance tasks.
• They can be used for draining, filtering, and refilling aircraft hydraulic systems with clean fluid, as well as for checking system operation and detecting leaks.
• Typically electrically-powered, these units deliver variable fluid volume, ranging from zero to approximately 24 gallons per minute, at pressures up to 3,000 psi.
• Operating at such high pressures requires extreme caution, as even a small leak can be dangerous, akin to a sharp knife.
• Regular inspection of lines for damage and ensuring they are free of kinks and twists is essential for safety.
• When not in use, hydraulic power unit lines should be stored neatly, preferably wound on a reel, and kept clean, dry, and free of contaminants.

Question 51

Ground Support Air Units

Answer 51

• Air carts are employed to supply low-pressure air, up to 50 psi high volume flow, for various ground operations.
• These operations include starting the aircraft engines and providing air for heating and cooling using the onboard aircraft systems.
• Typically, air carts consist of an APU (Auxiliary Power Unit) designed to meet the air supply needs of the aircraft on the ground.

Question 52

Ground Air Heating and Air Conditioning

Answer 52

• Airport gates typically offer facilities to supply heated or cooled air to aircraft.
• Permanent installations are utilized to cool or heat the air, connecting to the aircraft’s ventilation system through a large hose.
• Additionally, portable heating and air conditioning units are available, which can be positioned near the aircraft and connected via ducts to maintain comfortable cabin temperatures.

Question 53

Oxygen Servicing Equipment

Answer 53

• Before servicing any aircraft with oxygen, it’s crucial to consult the specific aircraft maintenance manual to determine the appropriate types of servicing equipment required.
• Two personnel are typically needed for oxygen servicing: one stationed at the control valves of the servicing equipment and another positioned to observe the pressure in the aircraft system. Effective communication between them is essential, especially in emergencies.
• Oxygen servicing should not be conducted during fueling, defueling, or other maintenance tasks that could pose an ignition risk. It should be done outside hangars.
• Aircraft oxygen is available in two forms: gaseous and liquid. Gaseous oxygen is stored in large steel cylinders, while liquid oxygen (LOX) is stored and converted into a usable gas in a liquid oxygen converter.
• Oxygen comes in three general types: aviator’s breathing, industrial, and medical. Only oxygen labeled as “Aviator’s Breathing Oxygen” meeting Federal Specification BB-0-925A, Grade A, or equivalent standards should be used in aircraft breathing oxygen systems. Industrial oxygen may contain impurities harmful to occupants, while medical oxygen, though pure, can freeze at high altitudes.

Question 54

Oxygen Hazards

Answer 54

• Gaseous oxygen is chemically stable and nonflammable. However, it accelerates the combustion of materials, causing them to ignite more rapidly and burn intensely in an oxygen-rich environment
• Oxygen can react with oil, grease, or bituminous materials to form highly-explosive mixtures that are sensitive to compression or impact
• Physical damage to or failure of oxygen containers, valves, or plumbing can lead to explosive ruptures, posing extreme danger to life and property
• Maintaining the highest standard of cleanliness is crucial when handling oxygen, and only qualified and authorized personnel should service aircraft gaseous oxygen systems
• Liquid oxygen, due to its low temperature (boiling at −297 °F), can cause severe “burns” (frostbite) upon skin contact, exacerbating the fire hazard.

Question 55

Types of Fuel and Identification

Answer 55

• Aviation Gasoline (AVGAS)
• Used in reciprocating engine aircraft.
• Three main grades: 80/87, 100/130, and 100LL (low lead), with a fourth grade, 115/145, used in large reciprocating-engine aircraft.
• The two numbers in the grade indicate lean mixture and rich mixture octane rating
• Identified by color coding matching the color band on piping and fueling equipment
• Turbine Fuel/Jet Fuel
• Powers turbojet and turboshaft engines.
• Three main types: JET A, JET A-1 (both made from kerosene), and JET B (blend of
  kerosene and AVGAS).
• Jet fuel is identified by the color black on piping and fueling equipment, but its actual color can be clear or straw-colored.
• Mixing Fuel
• Mixing AVGAS and turbine fuel can be detrimental and should be avoided.
• Adding jet fuel to AVGAS can decrease engine power and cause damage (detonation). - Adding AVGAS to jet fuel can lead to lead deposits in the turbine engine and reduce
  service life.

Question 56

Contamination Control

Answer 56

Contamination in aviation fuel, including water, solids, and microbial growths, poses a serious risk to engine function and safety. The primary method of control is prevention, although some contamination may still occur within the fuel system.

• Water Contamination
• Two forms: dissolved (vapor) and free water.
• Free water poses a risk of ice formation, leading to filter clogging and other issues.
• Water can appear as water slugs (drained after fueling) or entrained water (suspended droplets).
• Solid Contaminants
• Insoluble in fuel and include rust, dirt, sand, gasket material, lint, and shop towel
  fragments.
• Even tiny particles can damage or block fuel controls and mechanisms.
• Microbiological Growth
• Particularly problematic in jet fuel.
• Various microorganisms thrive in free water in jet fuel, introduced during refueling.
• Favorable conditions for growth include warm temperatures and the presence of iron oxide and mineral salts in water.

Effects of Microorganisms
- Formation of slime or sludge, fouling filters, separators, or fuel controls.
- Emulsification of fuel.
- Production of corrosive compounds that can damage fuel tank structure, including offensive odors

Question 57

Fueling Hazards

Answer 57

The volatility of aviation fuels presents a significant fire hazard, posing risks to both aviators and aircraft. Aviation fuel’s ability to change into a gas at low temperatures makes its vapor or gaseous state highly flammable.

• Volatility
• Aviation fuel does not burn in its liquid state; it’s the vapor or gas state that is combustible and powers the aircraft.
• Static Electricity
• Fuel flowing through a line generates static electricity.
• During flight, aircraft movement generates static electricity in the airframe, which, if not dissipated before refueling, can discharge through the fuel line.
• Static electricity discharge can ignite fuel vapors, leading to a fire hazard.
  Safety Measures
• Limit exposure to fuel vapors, as inhalation can be harmful.
• Promptly remove any fuel spilled on clothing or skin to prevent potential hazards.

Question 58

Fueling Procedures

Answer 58

Proper fueling procedures are crucial for aircraft safety and operation. Whether using over-the-wing or single-point fueling systems, following specific guidelines ensures the process is conducted safely and efficiently.

Over-the-Wing Fueling (Smaller Aircraft)

• Fueling ports on the top of the wing are utilized.
• Smaller aircraft are typically fueled using this method
  1. Turn off all aircraft electrical systems and electronic devices.
  2. Ensure pockets are empty to prevent items from falling into fuel tanks.
  3. Avoid carrying flame-producing devices during fueling.
  4. Use the correct type and grade of fuel, avoiding mixing AVGAS and JET fuel.
  5. Drain all sumps.
  6. Wear eye protection and other protective gear.
  7. Avoid fueling in the presence of blowing dirt or contaminants.
  8. Do not fuel during lightning within 5 miles or within 500 feet of operating ground radar.

Single Point Fueling (Larger Aircraft)

• Receptacles in the bottom leading edge of the wing are used to fill all tanks simultaneously. - Reduces refueling time, limits contamination, and minimizes static electricity risks.
• Prior to fueling, conduct the same checks and precautions as over-the-wing fueling.
  Mobile Fueling Equipment
• Position the fuel truck cautiously, ensuring no backing is required for a quick departure.
• Ground both the aircraft and the fuel truck, bonding them together with connecting wires.
• Protect the wing and aircraft from potential damage caused by spilled fuel or mishandling of equipment.
• Check fuel cap security before leaving the aircraft.
  Fueling from Pits or Cabinets
• Follow procedures similar to those with mobile equipment.
• Pits or cabinets often have permanent grounding, but aircraft and equipment grounding remains essential.

By adhering to these procedures, fueling operations can be conducted safely, minimizing risks to personnel and aircraft alike.

Question 59

Defueling

Answer 59

Defueling procedures vary depending on the type of aircraft. Always consult the maintenance/service manual for specific instructions and precautions. Defueling can be done either by gravity defueling or by using pumps to remove fuel from the tanks. Here are general precautions to follow:

1. Consult the Manual
   Before starting the defueling process, refer to the aircraft’s maintenance/service manual for
   detailed procedures and safety precautions.
2. Gravity Defueling
   If using gravity defueling, ensure you have a method to collect the fuel as it drains from the aircraft’s tanks. Follow the manual’s instructions carefully to avoid spills or contamination.
3. Pumping Method
   When using pumps to defuel, take care not to damage the tanks. It’s crucial to prevent the removed fuel from mixing with good fuel to avoid contamination issues.
4. Precautions
   - Ground both the aircraft and the defueling equipment to prevent static electricity
   discharge.
   - Turn off all electrical and electronic equipment onboard the aircraft to minimize ignition
   risks.
   - Have the appropriate type of fire extinguisher readily available for immediate use in case
   of emergencies.
   - Wear eye protection to safeguard against fuel splashes or spills during the de-fueling
   process.
   By adhering to these precautions and following the specific procedures outlined in the manual, defueling operations can be conducted safely and effectively, minimizing risks to personnel and equipment.