Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Module 17 > 17.6 Propeller Maintenance > Flashcards

17.6 Propeller Maintenance Flashcards

1
Q

What can cause propeller roughness?

A

May be caused by:

  • Bent blades
  • Blades out of track due to improper mounting
  • Imbalance
  • Blade angles out of tolerance
  • Spinner imbalance due to dirt, snow or ice inside the shell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When working with propellers what 3 different types of balancing are of importance?

A
  • Static balancing
  • Dynamic balancing
  • Aerodynamic balancing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are static and dynamic imbalance caused by?

A

Unequal mass distribution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the purpose of aerodynamic balancing?

A

To ensure each blade delivers an equal amount of thrust

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Which type of balancing should be sufficient especially for smaller props or aircraft?

A

In most cases static balancing will be sufficient. Only with larger propellers or with fast running propellers may dynamic balancing be necessary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is static balance?

A

A body capable of rotating about a fixed point is said to be in static balance when it’s centre of gravity lies on the axis of rotation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When is static balancing carried out?

A

Static balancing is carried out off the aircraft, either at manufacturer or overhauler in an approved propeller repair facility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

On what 2 planes is static balancing checked?

A

Horizontal and vertical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How can horizontal imbalance be rectified on fixed pitch wood propellers?

A

Can be corrected by applying small amounts of varnish or paint to the light blade. If larger amounts are required then solder can be applied to the metal tipping of the lighter blade

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How can vertical imbalance be corrected on fixed pitch wood propellers?

A

By adding weights to the hub

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are fixed pitch metal propellers statically balanced?

A

By removing some metal on the heavy side and then re finishing the propeller using a non-anodic protective coating such as Alodine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

For propellers of aircraft up to 5700kg what is the generally permissible tolerance ?

A

2gm. However the specifications of the manufacturer are binding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How are metal and composite variable pitch propellers balanced?

A

By placing lead washers on to a balancing stud within the hollow blade root/shank for horizontal balance while lead washers are placed in recesses of the hub for vertical balancing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How are minor adjustments made to metal and composite variable pitch propellers?

A

By applying lead wool in to the balancing tube located within the hollow root of the blade

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are Welch bolts used for?

A

On smaller propellers the lead wood (used for balancing) can be placed in the counter board area of the hub bolt heads.

The bolts are known as Welch bolts because of the Welch plug used to cap the bolt when lead wool is installed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How must dynamic balancing take place?

A

On a running engine

17
Q

What would most modern engines use to determine the level of propeller imbalance?

A
  • Propeller Balance Monitoring System (PBMS)
  • Information from the Magnetic Pickup Unit (MPU) and Active Noise Control Unit (ANCU)
  • Engine RPM and Altitude
18
Q

What are the 4 steps used to dynamically balance a propeller?

A

1: Obtain in flight vibration information
2: Ensure vibration is greater than permitted limits
3: Calculate the mass and location to reduce vibration to an acceptable level
4: Install balance weights and confirm vibration levels are within limits

19
Q

What type of propellers require aerodynamic balancing?

A

Propellers with high performance

20
Q

What is the Universal Blade Protractor used for?

A

To measure the propeller blade angle at a specific blade station to determine if the propeller is correctly adjusted

21
Q

What is blade tracking?

A

The ability of one blade to follow the other in the same plane of rotation. Tracking is held to reasonable limits to prevent roughness. To check tracking place a smooth board just under the tip of the lower blade

22
Q

What should be checked when inspecting surface protection?

A

That is 100% intact so that no moisture can penetrate

23
Q

After installation of new fixed pitch wood propeller the attachment bolts must be re-tightened after how many hours?

A

25 hours, with the torque prescribed

24
Q

After the initial re-tightening of the attachment bolts what are the intervals required to re-check them?

A

At least every 50 hours as humidity will cause the wood to shrink and expand

25
Q

What should wooden propellers be checked for?

A
  • Delimitation
  • Surface damage
  • protective strip damage and loose screws and rivets
  • Root/Shank damage (no repairs permitted)
  • Distortion of the propeller mounting boss
  • Blade warp
26
Q

What type of damage is not repairable and would be unusable?

A
  • Cracks across the grain
  • A splintered blade
  • Delimitation
  • Missing material
  • Cracks in the hub
  • Enlargement of the hub shaft bore
  • Elliptical bolt holes
27
Q

What is a permissible repair on the blade root?

A

No repair is permissible on the blade root at all

28
Q

When inspecting composite blades what are the two classes they can fall in to?

A

Skin perforated and skin not prefersted

29
Q

What is known as skin not perforated?

A
  • Abrasion
  • Scratches
  • Gauges
  • Nicks
  • Debonding
  • Delamination
  • Dents
30
Q

What is known as skin perforated?

A
  • Lightning strike

- Holes

31
Q

What are static checks?

A

Before carrying out a ground run certain checks need to be carried out with the engine not running. This is why they are called static checks

32
Q

What static checks are there?

A
  • Flight Fine Pitch Stop (FFPS)
  • Auto-Coarsening
  • Manual feather
  • Autofeather
  • Unfeather
33
Q

How can the feathering static checks take place?

A

By using an electric feathering pump to pressurise the oil to move the pitch change mechanism

34
Q

Following what procedures would static checks be carried out?

A
  • Engine installation
  • Propeller installation
  • Propeller governor installation
  • Propeller Control adjustments
  • When called for by the servicing schedule
35
Q

What are piston engines also known as?

A

Reciprocating engines and further classified as naturally aspirated or supercharged engines

36
Q

What is Manifold Air Pressure (MAP)?

A

The power developed by piston engines related to the air pressure in the engine air induction manifold

37
Q

How is turboprop engine power measured?

A

In shaft horsepower (SHP)

38
Q

What are the main causes of vibration?

A
  • Incorrect blade angle
  • Out of track
  • Bearing/grease leakage
  • Propeller security
  • Damaged blade bearings

Module 17 (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions