7.17 Aircraft Weight And Balance

Question 1

Difference between towing and taxiing

Answer 1

Towing requires a tug with a towing arm.
Taxiing is done using its own power.
Both are done on firm level ground.

Question 2

Marshalling

Answer 2

Marshalled is responsible for providing standard marshalling signals.

Marshalled must wear distinctive fluorescent.

Question 3

Marshalling

Answer 3

The person towing or taxiing an aircraft must obey all marshalling signals but has the final decision on whether to take notice of the signal or not.

Question 4

Precautions for taxiing.

Answer 4

Undercarriage is locked and ground pins are in.
Brake system is serviceable and pressurised to operate.
Correct number of personnel + a supervision.
ATC + ground control made aware of a/c movements.
Ensured nose wheel steering is connected.
Seat belts fastened

Question 5

Three reasons for towing an aircraft.

Answer 5

Pushback towing.
Maintenance towing.
Dispatch towing.

Question 6

Bridle (cable) towing.

Answer 6

Used when towing aircraft over soft ground.

Question 7

A/C jacking.

Answer 7

designed with 3-4 designated jacking points. (Primary and secondary).
Only use equipment specified in AMM.
Ensure A/C is in correct configuration before jacking.
Ensure lifting capacity of jacks is not exceeded.
Inspect condition of jacks.
Proper function of safety locks.
Condition of pins.
General serviceability.
Never use a jack that is leaking oil.

Question 8

Axle/bottle jacks

Answer 8

Used for wheel changes.

Question 9

Bipod jacks

Answer 9

Hydraulic unit, 2 fixed legs, 1 adjustable leg.
Used for arc lifts.

Question 10

Tripod jacks.

Answer 10

3 legs, used for vertical lifts.

Question 11

Quadruped jack

Answer 11

4 legs. 2 adjustable, 2 fixed

Question 12

Usual jack points

Answer 12

Main wing spar
Near nose
4th jack usually supports empannage

Question 13

Shoring.

Answer 13

A method of relieving stresses on the a/c whilst performing maintenance.
Support only, not used to jack aircraft.
To relieve the loads on the structure at secondary jacking points.

Question 14

Aircraft levelling.

Answer 14

Ensure it is level for jacking + lowering.
Use plumb-bobs or attitude indicators.

Question 15

Wheel chocking.

Answer 15

Wood or rubber.
Has a rope (lanyard).
Must be eased for feeling operations

Question 16

A/C securing
Light and heavy.

Answer 16

Help prevent damage from sudden storms.
Head the A/C into wind.

Light A/C - secured with ropes tied at tie down rings.

Heavy A/C
- tie down rings , rope, wires.
- equipped with surface control locks.

Question 17

Tie down procedure.

Answer 17

Use adequate tension but not too much.
Head into wind.
Install control locks, covers, guards.
Chock the wheels.
Periodically check the a/c.

Question 18

Parking an a/c

Answer 18

Reference must be made to AMM chapter 10.
May need to secure, drain water systems.
Scheduled maintenance is continued.

Question 19

Protection devices when storing an a/c

Answer 19

• Entry into tech log.
• Blanking inlet and exhausts on apu and engines, including sensors and probes to prevent prevent ingress of moisture and insects.
• attach a tag to the captains stick
• close all access
• smaller a/c can require flight control locking devices.

Question 20

Return to service. (Parking up to 2 days)

Answer 20

Blanks removed + safety devices.
Visual inspection
Entry in tech log cleared.
Reset systems that were deactivated for parking.

Question 21

What do you do when parking for extended periods in addition to the 2 day requirements.

Answer 21

Fuel tanks full to prevent microbiological corrosion.
Carry out water drain checks on fuel systems.
Toilet + water systems must be cleaned and drained.
Seat covers to prevent uv light damage.
Remove or disconnect the battery.
Door seals require greases to stop them drying and cracking.
Periodic visual inspections at 7 and 15 day intervals.
No evidence for bird nests or excrement.
Checking covers are still installed.
Periodically moving the aircraft to prevent brinelling of wheel bearings and flattening of the tyres.

Question 22

Storage of a/c

Answer 22

Maintenance programme must be continued.
The difference between storing and parking is that some form of extra protection is required against the elements.
Engines and APU can require draining and inhibiting.
Weekly checks. - visuals for bird nests and leaks.
Bi-weekly checks.

Question 23

Two main categories of aviation fuels

Answer 23

Turbine fuels.
Aviation gasoline.

Question 24

Aviation gasoline AVGAS.

Answer 24

Formulated to burn smoothly without detonation or knocking.
Graded by octane:
- 80 red
- 100 green
100 LL (low lead) blue

Question 25

Turbine fuels.

Answer 25

Jet a f.p. = -40 degrees
Jet a-1 f.p. = -47 degrees
Jet b F.p. = - 50 degrees

All have a light stray colour

Question 26

Two main methods of refuelling

Answer 26

Gravity or over-wing.
Pressure refuelling.

Question 27

Pressure refuelling.

Answer 27

Common method for large a/c.
Faster refuelling.
Reduces chance of static electricity igniting fuel.
Uses refuelling receptacles in the leading edge of the wing.
Refuelling pressure can be as high as 50 psi.
Defuel pressure is normally around 11psi.

Question 28

Grounding and bonding.

Answer 28

To ensure static discharge sparks do not occur.
Bonding is last thing to be removed.

Question 29

Safety precautions when refuelling.

Answer 29

No smocking signs must be displayed at a distance of 15m from fuelling equipment.
Fire appliances must be readily available.
Ground equipment must be moved away from the aircraft.
Fuel supply must be regularly checked for water contamination.

Question 30

Icing conditions.

Answer 30

Freezing conditions and moisture in the atmosphere.
Freezing rain or drizzle.

Question 31

Effect of ice on a/c

Answer 31

Decreases in lift
Increase in drag.
Decreases in propeller efficiency.
Propeller vibration
Loss of control
Malfunction of instruments.
Ice debris damage

Question 32

De-icing

Answer 32

Procedure to remove ice, snow, frost, slush.
De-icing fluids are normally applied heated

Question 33

Anti-icing.

Answer 33

Provides protection against the formation of ice.
Only valid for a period of time, called holdover time.

One step- combination of de-ice and anti-ice in one liquid.
Two step, de-ice followed immediately by anti-ice.

Question 34

De-ice/anti-ice fluids

Answer 34

Type 1,2,4 can be diluted with water.

Type 1 (orange) normally used for aircraft de-icing, limited anti-ice effect.

Type 2 used for anti-icing.
Type 3, compromise between type 1 + 2
Type 4 advanced version of type 2, longest holdover time.

Question 35

Anti-ice vs de-ice

Answer 35

Anti-ice sprayed cold.
De-ice sprayed heated.

Question 36

DC supplies

Answer 36

A set of batteries mounted onto a trolley or an engine driven DC generator.
Check to see if the a/c is serviceable before applying power.
The plug consists of 3 pins, handed so it can not be fitted the wrong way round.
A positive and negative pin as well as a smaller earth pin which also acts as a relay control pin.

Question 37

AC power supplies

Answer 37

115 VAC 1400 Hz / 3 phase
Diesel engine powered GPU
Battery powered GPU
- uses an inverter
- some can be charged simultaneously
Has 6 pins, handed so it
- 3 large pins for supply of 3 phase
- 4th large pin for ground/earth
- 2 small pins are DC control pins
Some a/c have 2 sockets, primary used first, secondary used if more power needed.

Question 38

Hydraulic ground supplies.

Answer 38

For use in a hanger, normally electrically driven.
Test rig must produce same pressure and flow rate as the a/c.
Connected using quick disconnect couplings.
The rig can require bleeding of air.
Ensure the rig is correct type.
Ensure fluid in rig is the same as In a/c.
Ensure switch positions correspond.
During testing:
- post safety engineers + signs
- follow AMM

Question 39

Pneumatic ground air units.

Answer 39

Air carts provide low pressure (up to 50psi) air that an be used to start the engines and heat and cool the a/c.
When disconnecting ensure that pressure is released first.

Question 40

Sand and dust.

Answer 40

Blanks and covers
Extra filters for air conditioning systems.
Maintenance carried out under cover.
ATA 100 chapter 5

Question 41

Hot weather

Answer 41

Over heating, slower cooling of brakes, longer take-off and landing distances.
May require an optional ground cooling unit
Tires wear faster.

Question 42

Raining conditions

Answer 42

Covers + blanks
Drain points are clear.