17.6 Propeller Maintenance Flashcards
Where is static balancing carried out
Off aircraft
Which propellers are normally not dynamically balanced
Small propellers
A body rotating about a fixed point is what
Static balance
Balancing propeller to reduce moment of imbalance is known as
Dynamic balancing
When must dynamic balancing be carried out on
Running engine
What is the universal blade protractor used to measure
- propeller blade angle at specific blade station to ensure propeller is properly adjusted
What is the protractor frame made out of
Aluminium
Aerodynamic balancing are used on what kind of propellers
- necessary for propellers with high performance
Reference station is normally set at either 30, 36 or 42 inch measurement on the propeller blade (T or F)
T
What is blade tracking
Ability of one blade to follow the same plane of rotation
What are the 2 main methods to check a blades tracking
- flat bench method
- block or pointer method
To check tracking, place smooth board under tip of lower blade
True
Explain flat tracking method
- smooth board placed under tip of lower blade and paper taped to it
- draw line with pencil
- lines should be separated by not more than 3mm
Explain block or pointer tracking method
- means of a heavy block or pointer method
- within 1/16 inch from opposite blades track
Airworthy damage limits described within?
AMM ATA chapter 61
Explain erosion
- loss of material from blade surface by small particles like sand/water etc
Ultrasonic inspections can be carried out on what materials
Wood, composites, ferrous, non-ferrous metals
Explain Eddy current inspection
- generates and measures an electric field that detects flaws or slightly be.ow surface of component being inspected
Cracks in the pain across the blade is a sign of what
Flexural vibrations
Indentations in the metal tipping can be filled by what
Soldering
Surface damage to wooden propeller blades can be repaired using what
Wood filler or mix of sawdust and aeroglue
Metal blades require thorough inspection after cleaning when
Every 100 hours or annually
As a protection against corrosion what can be applied to the hub after cleaning
Lubricant spray
Sub-classification of damage may also be sub-divided as what
- skin perforated damage
- skin not perforated damage
Explain airworthy damage and unairworthy damage
Airworthy - can be repaired in field
Unairworthy - damage exceeds limits of airworthy damage
What material is the tap test carried out on and with what
Composite blades with a metal coin
Why is the erosion strip attached to the composite blade LE for
- to show erosion effect on blade
Corrosion on metal propeller components can be classified into 3 types
- surface corrosion
- pitting
- intergranular corrosion
Metal propellers must be checked thoroughly after how long
- 100 hours/annually
Is repair permissible on blade root
No
Repair of damage
10x depth of nick for the leading and trailing edge
30x depth for the blade face and back
Explain steel propellers
- extremely durable and resistant to damage
What are static checks
- checks carried out without the need to run engines
