17.6.3 Blade Damage Assessment Flashcards
What can cause damage to propeller blades during flight?
Objects such as stones, dirt, and birds can strike against the propeller blades and hub, causing bends, cuts, scars, nicks, scratches, or other defects.
What happens if a defect in a propeller is not repaired?
Local stresses may develop, potentially causing a crack to form, which can lead to the failure of the propeller or hub.
What are the two categories of propeller blade damage?
Damage can be classified as airworthy or unairworthy.
What is ‘airworthy damage’?
Airworthy damage can be repaired in the field and does not affect flight safety characteristics.
What is ‘unairworthy damage’?
Unairworthy damage exceeds the limits of airworthy damage and requires more extensive repairs.
What is a crack in the context of propeller damage?
An irregular shaped separation within a material, usually visible as a narrow opening at a surface.
What does ‘debond’ refer to in propeller damage?
A separation of the metal erosion shield from the composite material in the blade.
What is delamination?
An internal separation of the layers of composite material.
What is a depression in propeller damage?
A surface area where the material has been compressed, but not removed, by contact with a sharp object.
What does ‘distortion’ mean in relation to propellers?
An alteration of the original shape or size of a component.
What is exposure in terms of propeller damage?
A condition in which material is left open to the action of the elements.
What is a gouge?
A small surface area from which material has been removed by contact with a sharp object.
What is impact damage?
Damage that occurs when the propeller blade or hub assembly strikes or is struck by an object.
What is a scratch in propeller terminology?
The removal of paint and a small amount of material not exceeding 0.5 mm.
What is a nick?
A small indent or notch, not deeper than 0.5 mm.
What is a split in a composite blade?
A delamination of a composite blade extending to the blade surface, typically found near the trailing edge or tip.
What is a dent?
A hollow or mark left by impact, blow, or pressure.
What is erosion in the context of propeller damage?
A gradual wearing away or deterioration due to the action of air contaminations like sand and dust.
What is corrosion?
A gradual wearing away due to a chemical action.
What is fatigue in propeller blades?
Fatigue failures typically occur near the blade tip but can happen in other areas when damage is ignored.
What should be inspected during a propeller inspection?
Inspect each whole blade, not just the leading edge, for erosion, scratches, nicks, and cracks.
Where can airworthy damage limits be found?
In AMM ATA chapter 61 of the related aircraft.
What is the primary method of propeller inspection?
Visual inspection, which includes using touch and other senses along with visual cues.
What is a tap test?
A method to inspect composite blades for delaminations and debonds by tapping with a metal coin.
What is penetrant inspection?
A method using fluorescent penetrant to detect small surface cracks on propeller blades.
What is ultrasonic inspection?
A method using sound waves to detect flaws on or below the surface of the component being tested.
What is eddy current inspection?
A method that generates and measures an electric field to detect flaws at or slightly below the surface.
What is magnetic particle inspection?
A method useful for finding cracks and imperfections at or near the surface of ferrous parts.
What is erosion in propeller blades?
The loss of material from the blade surface due to the action of small particles, typically near the leading edge.
What are the three types of corrosion in metal propellers?
Surface corrosion, pitting, and intergranular corrosion.
What is surface corrosion?
The loss of surface metal due to chemical action, usually visible with oxidation products.
What is pitting in propeller damage?
Visible corrosion cavities extending inward from the metal surface, which can lead to cracks.
What is intergranular corrosion?
Corrosion occurring in grain boundaries, often due to moisture retention.
What is impact damage in propellers?
Damage from a foreign object that can range from no visible damage to severe ground impact damage.
What special problems do wood or composite propellers face?
They can suffer from internal damage due to small strikes, leading to delamination or microcracks.
What should be checked in wooden propellers?
Look for glue line debonding, warping, and loss of protective coating.
What can clogged drain holes in propellers cause?
They can lead to moisture retention, causing further damage.
