Props Chapter 22 Review Questions
What is the purpose of local etching?
1. Helps show whether marks in small areas are cracks or only scratches. 2. Helps expose small cracks 3. Shows whether a crack has been removed. 4. Provides a simple means of inspecting the blade without removing or disassembling the propeller.
How may a composite propeller blade be tested for debond and delamination?
A coin-tap test, or the use of an impactoscope flaw detector
What special tool is needed for installation of a PT6A turbopropeller?
A special propeller puller?
What device is used for checking propeller blade angle?
A universal propeller protractor
What components comprise a dynamic vibration measuring system?
A vibration transducer, a photocell, magnetic pickup, or strobe electronic instrument.
Define the term major alteration as it applies to propellers?
An alteration which may cause an appreciable change in weight, strength, balance, performance, or others qualities affecting the airworthiness of the propeller.
Who is authorized to perform major repairs and alterations on propellers?
Appropriately rated repair station, manufacturer, or air carrier
Define the terms debond and delamination as they apply to composite propellers.
Debond is a separation of the metal erosion shield from the composition material in the blade. Delamination is an internal separation of the layers of composite material.
After a propeller is damaged in an accident, what inspections should be made?
Disassemble the propeller and carefully inspect the parts for damage and misalignment. Also, the crankshaft should be checked for proper alignment.
What items should be checked prior to the installation of a propeller on a crankshaft?
Inspect the shaft and hub for any surface defects and inspect bolts and bolt holes.
Can static rpm be adjusted on a fixed-pitch propeller?
No, there is no means to adjust static rpm on a fixed-pitch propeller.
Define a damaged metal propeller blade.
One that has been bent, cracked, or seriously dented.
What is meant by the term correctable vibration?
Ones that relate primarily to the propeller track and balance and to the balance of shafting, accesories, etc.
What types of hubs are generally used to mount propellers on engine crankshafts?
Splined/ tapered/ flange
Purpose of the cones used in the installation of a propeller on a splined shaft?
The cones help seat the propeller properly on the shaft, and serve as a replaceable part instead of having to replace the whole propeller.
Describe the repair of small cracks parallel to the grain in a wood propeller.
The cracks should be filled with an approved glue, dried, and then sanded to achieve a smooth surface
Explain how the fit of a tapered hub and shaft is checked.
The fit can be checked by applying Prussian blue to the hub and shaft. The hub is installed and the retaining nut tightened. Then, the hub is removed and the degree of surface contact is shown by the transfer of the Prussian blue. The contact area should be 70 percent or more.
Who is authorized to repair damaged steel propeller blades?
The manufacturer
How does the retaining nut for a propeller serve as a puller when the propeller is removed?
The retaining nut is backed off and bears against the snap ring, pulling the propeller from the shaft.
What should be done to aluminum-alloy blades that have pitted leading edges as a result of normal wear?
These blades can be reworked by removing sufficient material to eliminate the defect.
How may minor damage of the leading and trailing edges of a steel blade be repaired?
This can be smoothed by handstoning, as long as the damage is not deep
What sequence should be followed during tightening of propeller attachment bolts?
Tighten bolts across from each other! Turn the bolts until they are finger tight, then use a torque wrench to tighten them to the specified value, then safety the bolts.
What is the purpose of checking propeller track?
To ensure that all blades of a propeller are flying in the same plane of rotation.
Why is a rear-coned spacer used with some installations?
To prevent the front cone from bottoming on the forward ends of the splines.
What are three methods of measuring the phase angle of the propeller during dynamic balancing?
Use of a photocell, a magnetic pickup, or a strobe light
