17.6.2 Blade Tracking Flashcards
What is blade tracking?
Blade tracking is the ability of one blade to follow the other in the same plane of rotation.
Why is tracking held to reasonable limits?
Tracking is held to reasonable limits to prevent roughness and vibration.
When may a tracking check be called up?
A tracking check may be called up after a propeller has been installed or if there is any reason to suspect the dynamic balance.
What is a classic case for suspecting dynamic balance issues?
A propeller that has suffered an impact from an object, particularly if vibration occurs.
Where is measurement usually conducted for tracking checks?
Measurement is usually conducted at the master station.
What is the fixed reference point for measuring blade distances?
The fixed reference point can be mounted on the engine or placed on the ground.
How is the distance measured during a tracking check?
The distance between a blade and the pointer is measured, and the propeller is turned by hand to enable measurements for each blade.
What should be done if the track is not within limits?
If the track is not within limits, the propeller has to be removed and returned to the manufacturer.
What must be ensured before performing a tracking check?
It is important that the propeller blade angles are all set at the same value before doing a tracking check.
How can the track on small wooden propellers be adjusted?
The track can sometimes be adjusted by inserting shims between the flange and the boss.
What are the two main methods for checking blade tracking?
The two main methods for checking blade tracking are the Flat Bench Method and the Block or Pointer Method.
Describe the Flat Bench Tracking Method.
Place a smooth board just under the tip of the lower blade and tape paper to it. Make small pencil marks as you move the blade tip, then center the blade and draw a line across it.
What should the separation between lines indicate in the Flat Bench Tracking Method?
The lines should be separated by not more than 3 mm (1/8 inch) or by the measurements designated in the maintenance manual.
What could differences greater than specified figures indicate?
Differences greater than the figures designated may indicate bent blades, improper installation, or foreign particles between the hub and crankshaft mounting faces.
Describe the Block or Pointer Tracking Method.
Rotate one blade down, place a solid object next to the propeller tip, and rotate the propeller to see if the next blade tracks through the same point.
