17.6 Flashcards
Three types of propeller balancing?
Static balancing
Dynamic balancing
Aerodynamic balancing
Static balancing is usually carried out by who?
Manufacturer or at overhaul
Where should centre of gravity always lie?
On the axis of rotation
What is horizontal balancing?
Varnish or paint can be added, or solder to tip
What is vertical balancing?
Weights can be attached to the hub
For propellers of aircraft up to 5700kg what is the permissible tolerance?
2gm
What can secure the wool in place that is placed in the balancing tube?
Welch plug
Dynamic balancing must be carried out when engine is…?
Running
Moment of imbalance caused by the lateral shift of what?
Of the blades Centre of Gravity
One method of dynamic balancing?
Weights attached to to each blade
A polar diagram is drawn to show where biggest imbalance is
Heaviest weight added to where biggest imbalance is
Four steps to dynamically balance a propeller?
- Obtain in flight vibration info
- Ensure vibration is out of tolerance
- Calculate mass and location of vibration
- Install balance weights
Aerodynamic balancing only required for what propellers?
High performance propellers
What is blade tracking?
Blades need to follow each other in direction of rotation
Cracks in the paint of wooden propellers are signs of what?
Flexural vibrations
If loose tipping rivets are found beneath wood what should happen?
Propeller taken out of service immediately
When installing new wooden fixed propellers, attachment bolts must be re-tightened after how many flying hours?
25 hours
What damaged of wooden propellers cannot be repaired and propeller is unusable?
Cracks across grain
Splintered blade
Delamination
Missing material
Cracks in hub
Enlargement of the hub shaft bore
Elliptical bolt holes
After re tightening of attachment bolts on wood prop, and then checked every what?
50 hours
Why are metal propellers subject to metal fatigue?
Caused by high dynamic loads
Recommended measures for care of metal propellers?
Maintenance instructions
RPM limitations
Never taxi at high power if sand, stones can be sucked into propeller
Clean propeller regularly and rub with an oily cloth or car polish
Do not cover propeller
When pulling use propeller root and not blades
Carry out pre and after flight inspection for nicks
Every 100 hours or annually inspect propeller
What is important to remember when repairing a damaged metal blade?
No repairs are permitted on the blade root
All repairs for steel propellers must be done by who?
Approved repair facility
For composite propellers damage is either what or what?
Skin not perforated damage
Or
Skin perforated damage
Types of Skin perforated damage?
Lightning strikes
Holes
The air pressure in the engine air induction manifold is known as what?
Manifold air pressure or MAP
In super charged engines what is MAP called?
Boost pressure
What do you set the propeller to if doing a reference RPM check?
Fine pitch
When doing a reference RPM check ensure propeller is facing into wind and wind isn’t in excess of what?
25kmh
During ground running where should RPM lever be put?
Constant speed range
RPM should reduce then stabilise
To determine engine is operating correctly what should be monitored?
Exhaust gas temperature (EGT)
Fuel flow (Wf)
Must be monitored against referenced torque and RPM
There is always a relationship between what torque and what else?
RPM
Fuel flow
EGT
Turbo prop engine power is measured in what?
Shaft horse power
Two examples of skin perforated damage?
Lightning strikes
Holes
