Types of airframe structure?
Monocoque, semi-monocoque (skin, stringers, frames) and truss.
- Most airliners: semi-monocoque, stressed skin
- Fail-safe: loss of one part does not cause failure
- Fatigue: cracks grow under repeated loads
DGCA Technical General · 25 questions
Airframe & Structures: DGCA Technical General Questions and Answers
25 practice questions on Airframe & Structures with answers and explanations, plus the key concepts and formulas, from the TrueHeading question bank.
About this topic
Use this page to revise Airframe & Structures for the DGCA Technical General paper. Below are the key ideas first, then 12 practice questions with answers and explanations, picked from the 25 questions in the TrueHeading bank for this topic.
In short: Monocoque, semi-monocoque (skin, stringers, frames) and truss.
Open the full set in the student zone to answer every question, track your accuracy and take timed mock tests.
Key concepts: Airframe & Structures
4 ideas to know cold.
Limit load and ultimate load?
Ultimate load = 1.5 × limit load. The structure must carry limit load without permanent deformation and ultimate load without failing.
What are the main structural members of a wing?
Spars (main load), ribs (shape), stringers (stiffen skin), skin (shear, torsion box).
- Wing box carries torsion
- Fuel is often stored in the wing box
- Wing loads in flight: bending up
What are fail-safe, safe-life and damage-tolerant?
Fail-safe: redundancy so that one failure is not catastrophic. Safe-life: replace after a fixed life. Damage tolerant: inspection to find cracks before critical.
- Fatigue is caused by cyclic loads
- Pressurisation cycles are the main fuselage fatigue load
- Corrosion protection: anodising, paint
Practice questions: Airframe & Structures
Tap “Show answer” after you have tried each one.
Q1A monocoque structure carries the loads mainly in:
- the engine mounts
- the skin
- the longerons
- the frames only
Show answer
Answer: B. the skin
Monocoque ("single shell") relies on the stressed skin.
Q2In a semi-monocoque fuselage the loads are carried by:
- the skin only
- the stringers only
- the frames only
- the skin, frames, formers and stringers (longerons)
Show answer
Answer: D. the skin, frames, formers and stringers (longerons)
The skin shares the loads with the internal structure.
Q3The ribs of a wing:
- carry the bending loads
- maintain the aerofoil shape and transfer loads from the skin to the spars
- support the engine
- are only used for fuel tanks
Show answer
Answer: B. maintain the aerofoil shape and transfer loads from the skin to the spars
They are the chordwise members.
Q4The main load on a wing in flight is:
- bending downward on the ground only
- tension on the upper surface
- bending upward, with compression on the upper surface and tension on the lower
- shear only
Show answer
Answer: C. bending upward, with compression on the upper surface and tension on the lower
In flight lift bends the wing up: upper skin in compression, lower skin in tension.
Q5A fail-safe structure is one in which:
- all parts are replaceable in flight
- failure leads to immediate collapse
- no member will ever fail
- failure of a single member does not result in catastrophic failure
Show answer
Answer: D. failure of a single member does not result in catastrophic failure
Load paths are redundant.
Q6The safe-life concept means that a component:
- is retired after a specified number of flight hours or cycles
- can be used until it fails
- is inspected only on failure
- has an infinite life
Show answer
Answer: A. is retired after a specified number of flight hours or cycles
It is applied to components such as landing gear.
Q7Corrosion is best prevented by:
- protective coating, anodising and regular cleaning
- painting only the engine
- running the aircraft more often
- using more oil
Show answer
Answer: A. protective coating, anodising and regular cleaning
Surface treatment and drainage reduce the risk.
Q8Composite materials such as carbon fibre offer:
- high weight
- high strength-to-weight ratio and fatigue resistance
- low strength
- poor fatigue properties
Show answer
Answer: B. high strength-to-weight ratio and fatigue resistance
Their drawback is damage that may be hidden within the layers.
Q9Titanium is used in aircraft because of its:
- low cost
- easy machining
- high strength and heat resistance at moderate weight
- low strength
Show answer
Answer: C. high strength and heat resistance at moderate weight
It is used near engines and in high-stress parts.
Q10The oval shape of the window in a pressurised cabin avoids:
- radio interference
- weight increases
- visibility problems
- stress concentration at corners which leads to cracks
Show answer
Answer: D. stress concentration at corners which leads to cracks
Square corners concentrate stress.
Q11The landing gear oleo strut absorbs shock by:
- using rubber bands
- compressing gas and forcing oil through an orifice
- using springs only
- sliding on rails
Show answer
Answer: B. compressing gas and forcing oil through an orifice
It combines pneumatic spring and hydraulic damping.
Q12Fusible plugs in aircraft wheels:
- release tyre pressure at high temperature to prevent tyre burst
- indicate tyre wear
- increase brake pressure
- hold the tyre in place
Show answer
Answer: A. release tyre pressure at high temperature to prevent tyre burst
They melt at a given temperature.
More DGCA Technical General topics
Aerodynamics & Performance181 QFlight Controls & Stability38 QPowerplant79 QPropellers32 QAircraft Systems116 QPitot Statics35 QBarometric Altimeters61 QRadio Altimeters37 QVertical Speed Indicators (VSI)32 QAirspeed Indicators24 QAirspeeds41 QMach55 QGyroscope52 QAttitude Indicators20 QTurn and Slip50 QINS, IRS and FMS32 QEFIS24 QAutoflight23 QFlight Director21 QEICAS / ECAM24 QEngine Instruments29 QTemperature Indicators34 QFuel Systems35 QCompass54 QWarning & Recording Systems33 QTCAS39 Q
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