Certification: Stress and Loading Flashcards
What other exams does the Mass and Balance exam complement?
Flight planning
Operational Procedures
Performance
Where are the performance and design requirements for aeroplanes set out in?
Cs 25
Cs 23
What is the CS 25 and to which airplanes does it apply?
Certification Specification 25:
- All multi-engine jets
- All multi-engine turboprop
- NOT in the commuter catergory
- > 9 passenger seats
- MTOW > 5700 kg
What is the CS 23 and to which airplanes does it apply?
Certification Specification 23:
- All aircraft = or < 9
- Take-off mass < 5700 Kg
- Commuter category propeller driven twins:
- MTOW = or < than 8618 kg and
- 19 passenger seats or less
What are other similar documents in other states?
FAR 25 and FAR 23 in the US
With what other operating rules is the CS25/23 combined? What does it define?
Operating Rules specified in EU-OPs, define the standard of safety for aeroplanes engaged in public transport operations
What are Mass and Balance calculations a essential precursor of? what does it establish?
- Performance calcultations
- Limiting masses that ensure that the space required does not exceed the space available.
What forces create stresses in the aircraft structure?
What is the definition of stress?
What kind of stresses can we find?
How do they act?
What do they do?
- Lift, weight, thrust and drag
- Stress = Force/cross-sectional area to which it is applied
- Twisting or torsion, tension, compression or shear
- Individually or together
- Bend, creates tension on the outside and compression on the inside
What’s the name of the stress at which the structure fails?
Ultimate stress = fail point for a single application of a static load
What can cause cumulative damage and what does it end up in?
- Loading and unloading structure many times below the ultimate stress.
- Structure failing catastrophically well below ultimate stress
What’s metal fatigue and does fatigue affect to other structures? How are civil airliners designed to prevent fatigue?
- cumulative stress in metal structures.
- yes, but they react in a different way
- Creating a safe design where crack-arrest features and parallel load paths allow the aircraft to fail in some degree until a periodic inspection reveals the failures and components canbe replaced
What does MZFM stand for and how is it defined?
Maximum Zero Fuel Mass: maximum permissible aircraft weight disregarding fuel
What are the main loads on a wing?
What do they incorporate?
Beding loads
Tension and Compression (both in flight and on the ground
Where is the maximum bending?
At the wing root
What reduces the bending moment of lift?
Fuel & Engine moment
How are primary bending and shear loads controlled?
By observing “g” and loading limits, in particular MZFM
What does the manufacturer’s limit ignore and what does he/she ensure?
Effect of fuel load in the wings
Ensures that the value of maximum bending of the wing at the wing root is not exceeded at the designed maximum load facto of 2.25g of the aircraft at the MZFM
What is aerodynamic flutter?
An undamped oscillation caused by aerodynamic imbalance
How are foces on spars affected?
By the amount of fuel in the wing