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ATPL Mass And Balance > Datum, Moments, And Determining CG > Flashcards

Datum, Moments, And Determining CG Flashcards

1
Q

In straight and level flight what is the sum of all the forces

A

0

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2
Q

What is a moment

A

The tendency of a force to rotate round an object round a axis

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3
Q

What is the moment formula

A

Moment = mass x balance arm

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4
Q

What is a balance arm

A

The distance from the datum point to the CG of mass

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5
Q

What is the formula to find CG position

A

CG = total moment / total mass

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6
Q

How can you ensure you remain within the CG limits throughout the whole flight

A

Calculate CG for take off / zero fuel / landing mass

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7
Q

Where must CG fall

A

Within the Mean Aerodynamic Chord (MAC)

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8
Q

How do you find the %MAC

A

% MAC =

(CG arm - LeMAC)/ mean aerodynamic chord x100

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9
Q

In what ways can the CG be changed to ensure it falls within the limits

A

Moving existing load to different parts of the aircraft

Removing or adding load

Adding ballast

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10
Q

What is the formula to determine how much mass you need to move to change the CG

A

m/M= d/D

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11
Q

How must ballast be entered on a load sheet

A

As ‘unusable’ fuel

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12
Q

Who’s responsibility is it for weighing a aircraft

A

Operators responsibility

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13
Q

Why must a aircraft be weight before it enters service

A

To establish its mass and centre of gravity

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14
Q

What is the period of re-weighing for individual aircraft

A

4 years

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15
Q

What must happen when a modification on mass and cg is made

A

Accounted and documented

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16
Q

What must be done if the effects of a modification on mass and centre of gravity are not known

A

Aircraft must be re-weighed

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17
Q

What is the definition of a fleet aircraft

A

A group of aircraft of the same model and configuration

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18
Q

What the weighing schedule for a aircraft fleet between 1-3 aircraft

A

4 years

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19
Q

What is the weighing schedule for aircraft in a fleet of 4-9 aircraft

A

2/3 of the aircraft must be weighed every 4 years

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20
Q

How many points of contact does a aircraft need to have when being weighed

A

Min 3

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21
Q

What must the location of the weighing of a aircraft be like

A

In a hanger with the air conditioning off

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22
Q

What must the exterior of the aircraft be like for weighing

A

Washed and dry

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23
Q

What must the load of the aircraft be like for weighing

A

Tanks drained with only unusable fuel remaining

Inventory checked to make sure no extra items

Hydraulics and engine oil full

24
Q

When must the aircraft be reweighed due to the effect of modifications

A

When the dry operating mass changes by more than 0.5% of the max landing mass

25
Q

What is the purpose of standard mass values

A

To speed up the boarding process

26
Q

What is the standard mass for flight crew

A

85kg

27
Q

What is the standard mass value for cabin crew

A

75 kg

28
Q

What is the categorisation of a child

A

2> 12 years of age

29
Q

When can a holiday charter flight no longer be classed as holiday charter

A

When more than 5% of the seating capacity is non revenue load

30
Q

How often does weighing equipment need to be calibrated

A

Every 2 years

31
Q

What are the effects of mass distribution

A

Stress on the aircraft

32
Q

What is stress

A

The force divided by cross sectional area

33
Q

What are the different types of stress

A

Torsion (twisting)

Tension ( pulling apart)

Compression (pushing together)

Shear (one layer sliding over another)

34
Q

What types of stress occur if an object is bending

A

Tension
Compression
Shear

35
Q

What are the 3 different options for crew weights

A

Actual masses of the crew

Standard masses of the crew (85/75kg)

Other standard masses acceptable to easa

36
Q

If an aircraft had less than 10 seats how is the passenger weight to be calculated

A

Verbally asking the passenger

37
Q

Standard mass for a child

A

35 kg

38
Q

How must the weight of checked baggage be calculated for a aircraft with <18 seats

A

Must be weighed

39
Q

How must the weight of checked baggage be worked out for a aircraft with >20 seats

A

Standard masses may be used

40
Q

What is design load

A

The load (or stress) measured in G that the aircraft is designed to not go over

41
Q

What is the ultimate load

A

The load (or stress) measured in G that the aircraft structure will fail at

42
Q

How is the ultimate load calculated

A

When the aircraft can hold a load (or stress) of over 1.5 (50% extra) the design load limit for more than 3 seconds

43
Q

What is the load limit “proof- test”

A

When the flying controls/ gear etc should function normally for 3 mins at 1.125 times the design load limit (12.5%) over

44
Q

When is a material said to have “failed” from fatigue

A

When a small crack reaches a critical size that it instantaneously becomes a large fracture across a component

45
Q

What does fatigue require before failure

A

Fatigue requires a number of cycles before failure

It is a medium to long term source of airframe damage

46
Q

How much does fatigue increase by per % if weight increase

A

1% weight increase = 5% fatigue consumption increase

47
Q

Effects of s forward cg

A

Excessive longitudinal stability

Unresponsive to control inputs

Reduces aircraft performance

48
Q

Effects of excessive aft cg

A

Controls feel very light

Easy to overstress aircraft

In light aircraft spin is more difficult / impossible to recover from

49
Q

If you want to commit aviation with a MSTOM of 63,060 in the MRJT how much taxi fuel can you have

A

No more than 260kg

50
Q

What tank do you use first and why

A

Centre, relieves stress at wing roots

Fuel in roots can be gravity fed

51
Q

What fuel tank is used for take off and why

A

Wing tanks

Usually fuel you know works (ie had with you before)

Where as centre tank is usually straight from the bowser

52
Q

For the MRJT what is the passenger mass

A

84kg regardless of age

53
Q

For the MRJT what is the passenger baggage Weight

A

13kg

54
Q

For the MRJT what is the crew weights

A

Both flight and cabin = 90kg (however they are already accounted for in variable load)

55
Q

How can you gross error check a load sheet

A

1) ensure allowed take off mass selected is the lowest mass
2) make sure max mass is not exceeded
3) the difference between limiting mass and actual take off mass should be the “underload before LMC”

56
Q

What are the 4 facts about LMC

A

Command has to be notified of any LMC

Can happen after engine start

LMC limits set out in operations manual

Underload adjusted by value in LMC

57
Q

What is factored stall speed

A

Vs x 1.3

May give you either factored stalling speed or unfactored stalling speed

= RTFQVCX2

ATPL Mass And Balance (3 decks)

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