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
What is the purpose of standard mass values
To speed up the boarding process
26
What is the standard mass for flight crew
85kg
27
What is the standard mass value for cabin crew
75 kg
28
What is the categorisation of a child
2> 12 years of age
29
When can a holiday charter flight no longer be classed as holiday charter
When more than 5% of the seating capacity is non revenue load
30
How often does weighing equipment need to be calibrated
Every 2 years
31
What are the effects of mass distribution
Stress on the aircraft
32
What is stress
The force divided by cross sectional area
33
What are the different types of stress
Torsion (twisting) Tension ( pulling apart) Compression (pushing together) Shear (one layer sliding over another)
34
What types of stress occur if an object is bending
Tension Compression Shear
35
What are the 3 different options for crew weights
Actual masses of the crew Standard masses of the crew (85/75kg) Other standard masses acceptable to easa
36
If an aircraft had less than 10 seats how is the passenger weight to be calculated
Verbally asking the passenger
37
Standard mass for a child
35 kg
38
How must the weight of checked baggage be calculated for a aircraft with <18 seats
Must be weighed
39
How must the weight of checked baggage be worked out for a aircraft with >20 seats
Standard masses may be used
40
What is design load
The load (or stress) measured in G that the aircraft is designed to not go over
41
What is the ultimate load
The load (or stress) measured in G that the aircraft structure will fail at
42
How is the ultimate load calculated
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
What is the load limit “proof- test”
When the flying controls/ gear etc should function normally for 3 mins at 1.125 times the design load limit (12.5%) over
44
When is a material said to have “failed” from fatigue
When a small crack reaches a critical size that it instantaneously becomes a large fracture across a component
45
What does fatigue require before failure
Fatigue requires a number of cycles before failure It is a medium to long term source of airframe damage
46
How much does fatigue increase by per % if weight increase
1% weight increase = 5% fatigue consumption increase
47
Effects of s forward cg
Excessive longitudinal stability Unresponsive to control inputs Reduces aircraft performance
48
Effects of excessive aft cg
Controls feel very light Easy to overstress aircraft In light aircraft spin is more difficult / impossible to recover from
49
If you want to commit aviation with a MSTOM of 63,060 in the MRJT how much taxi fuel can you have
No more than 260kg
50
What tank do you use first and why
Centre, relieves stress at wing roots Fuel in roots can be gravity fed
51
What fuel tank is used for take off and why
Wing tanks Usually fuel you know works (ie had with you before) Where as centre tank is usually straight from the bowser
52
For the MRJT what is the passenger mass
84kg regardless of age
53
For the MRJT what is the passenger baggage Weight
13kg
54
For the MRJT what is the crew weights
Both flight and cabin = 90kg (however they are already accounted for in variable load)
55
How can you gross error check a load sheet
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
What are the 4 facts about LMC
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
What is factored stall speed
Vs x 1.3 May give you either factored stalling speed or unfactored stalling speed = RTFQVCX2