17.2.2 Composites Flashcards
What are composite propellers?
Composite propellers are lighter in weight and stronger than metal propellers.
What is a challenge with composite propellers?
Damage can be difficult to detect apart from very minor scratches.
Who can repair composite blades?
Composite blades cannot be repaired by anyone other than an approved repair organisation. Field repairs are not permitted.
What materials are used to protect composite propellers?
Nickel or stainless steel erosion shields are bonded to the leading edges.
How do some composite blades prevent blade tip erosion?
Some designs incorporate a stainless steel wire mesh in the laminations.
What is used for de-icing in most composite blades?
Most composite blades use an external boot for de-icing.
What is the construction method for composite propellers with a metal spar?
The spar runs through the centre of the blade, with low-density foam or honeycomb as filling material.
What materials are used for the spar in composite propellers?
The spar can be made from titanium, aluminium alloy, or stainless steel.
What is the purpose of the heating element in composite blades?
The heating element is on the inner part of the surface of the leading edge for de-icing.
How are composite blades constructed without a metal spar?
They comprise two carbon fibre components that form the spar, with a hollow centre filled with polyurethane foam.
What is the advantage of the carbon fibre spars in composite blades?
They provide added strength to the root of the blade.
What materials are metal propellers typically made from?
Metal propellers are constructed from either aluminium alloy or steel.
What is the preferred alloy for metal propellers?
Duralumin is preferred as it is hard, strong, and easily forged.
What is a disadvantage of solid steel blades?
Even minor damage is considered a major repair only to be carried out by the manufacturer.
What are the benefits of aluminium propellers?
Aluminium alloy is more durable than wood and requires less maintenance.
