Questions

1°) What about the Structural Guarantee?
2°) Are there exclusions to the Structural Guarantee?
3°) A propeller blade has broken upon contact with the ground:
- Can I use the other two in order to build a new set?
- What about the hub and the screws?
4°) I experienced an impact from a stone during take-off.
      I can see a small hole on the leading edge of the propeller:
- Is this dangerous?
- Can it be repaired?
5°) If the hole is greater than 5mm or if there are more than 10 impact incidents, can I repair it?
6°) If I see that a blade is not totally rigid or solid or that it is deformed, what should I do?
7°) What advantages can I expect from a DUC propeller?
8°) How should the propeller pitch be adjusted in order to attain increased Climb rate or cruising speed?
9°) Why are the adaptor spacers of different lengths?
10°) What is a lengthener Rotax 4 stroke, and why are they of different lengths?
11°) What maintenance precautions are necessary in order to ensure my new DUC propeller is kept in perfect condition for me to continue using it for many years while maintaining its original efficiency?
12°) Can I paint DUC Carbon Fiber products?
13°) Can I mount a hub directly onto the propeller shaft or do I always need an adaptor?
14°) What is better, a 2 blade or a 3 blade?
15°) I am going to place my order, how long before delivery?
16°) Is the Turbo Spinner adapted for any aircraft and engine?
17°) How many different models are available?
18°) What is Anodized Aluminum?
19°) A Rotax 2 stroke can have 5 different gear box reduction: 2,58 - 2,62 - 3 - 3,47 - 4. How that influences the choice of the propeller?
20°) How do the engine’s specifications affect the choice of diameter?
21°) How is done the static balancing of a propeller?

Answers

1°) Guarantee

With M.O.R.E, Love4aviation.com's worldwide guarantee for DUC propellers (which include its accessories) is 6 years or 600 hours. Love4aviation.com warrants this propeller and all accessories to be free from defects in materials and workmanship for a period of six years or 600 hundred hours from the date of purchase. Love4aviation.com will, at their option, either repair or replace any defective propeller or part. This warranty does not apply to components damaged by misuse or neglect.
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2°) Guarantee Exclusions

The guarantee does not cover incorrect installation of the propeller or of its components by the client. It does not cover impact by objects, stones or gravel. It does not cover normal wear and tear of the blades due to abrasion. The life expectancy of a blade under normal conditions is 6 years or 600 flight hours. It does not cover exposure of the parts to chemicals unless recommended by the manufacturer.
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Particular Guarantee Exclusions

The guarantee does not cover any propellers or components thereof which have touched the ground or any other solid surface, or which have sustained an accident after a hard landing or a landing on unprepared ground. In this case, it is necessary to contact your account manager in order to determine if it is possible to repair the part.
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3°) A propeller blade has broken upon contact with the ground:

- Can I use the other two in order to build a new set?

- What about the hub and the screws?

Only an authorised agent can know if this is acceptable. Normally, when a propeller touches the ground, even if only one blade seems to have sustained an impact, the other(s) may also be damaged and unfit for use. In general, they will not be in good condition. The hub and the screws are more likely to be salvageable and useful. Normally, it is necessary to change the damaged blades with blades which have the same balance as the rest, or to change the complete blade set.
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4°) I experienced an impact from a stone during take-off. I can see a small hole on the leading edge of the propeller:

- Is this dangerous?

- Can it be repaired?

In general, an impact from a stone which is less than 5 mm is not dangerous because it only causes a slight wear which has no effect on safety and use of the propeller. Minor damage should be repaired when the number of impact incidents is greater than 10 in total. The procedure is simple: send the propeller to Duc propellers or order the "DUC Repair Kit" which is recommended by the manufacturer.
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5°) If the hole is greater than 5 mm or if there are more than 10 impact incidents, can I repair it?

In this case, we suggest that you send us the propeller for analysis. We will determine whether it is possible to repair it. Sometime a small impact on the trailing edge is much more harmful than one of the same nature which is closer to the blade base. The blade may be repaired provided that the repair does not affect the weight of the blade and, consequently, the momentum of the propeller. Even if it is possible to repair it, this will not guarantee that the repaired propeller will be the same as a new one. Even though this repair will extend the life of the propeller over many years it will have impaired performance compared to a new propeller.
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6°) If I see that a blade is not totally rigid or solid or that it is deformed, what should I do?

Something unusual must have happened. Carbon fibre maintains its rigidity and its resistance for many years unless it is exposed to abnormal use or has been subjected to an impact or some other damaging occurrence. In all cases, it is important to immediately stop flying and to remove the complete propeller so that it can be inspected by Love4aviation's team. A blade in this state is not airworthy.
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7°) What advantages can I expect from a DUC propeller?

The performance improvement from a new DUC propeller depends on the type of aircraft, engine and propeller pitch adjustment. All the flight tests have demonstrated that the aircraft performance are improved compared to its performance with propellers made of wood, aluminium and fibreglass but the results are not homogeneous. Further testing would be necessary to determine performance improvement for specific cases. In general, the improvement is noticeable and very obvious.
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8°) How should the propeller pitch be adjusted in order to attain increased climb rate or cruising speed?

Normally, for all propellers with variable pitch, whether they are adjustable on the ground or in the air, when climb rate is increased, cruising speed is reduced and vice versa. A compromise must be made to satisfy the preferred flight characteristics. By modifying the pitch by a slight angle, the desired performance can be attained and the maximum output power can be realised.
To adjust the pitch angle of the blades, please use the recommended adjustment tool and follow the instructions recommended by the manufacturer who supplied you with your new propeller. This procedure is very precise and should be accomplished with precision and accuracy. If in doubt, it is preferable to ask us or to call a Love4aviation's account managers. They provide year-round technical support.
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9°) Why are the adapter spacers of different lengths?

The price list shows that certain parts are called "adapter spacers". There are different lengths for different engines (previous generation Rotax, new generation Rotax, Jabiru). These extensions are used to connect the motor shaft or the gearbox output to the propeller hub. These parts are important because the fixation holes depend on the type and model of the engine. In some cases, they are not even needed. It is essential to know the exact specifications of the engine and the aircraft in order to know if it is required to buy an adaptor spacer or whether the propeller assembly can be mounted directly on the engine shaft. The length of the extension guarantees that the mounting plate of the propeller spinner does not come into contact with the engine or gearbox cowling.
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10°) What is a spacer Rotax 4 stroke, and why are they of different lengths?

Similar to the spacer, they are used to separate the spinner's mounting plate from the engine and gearbox cowling. They are used when the nose of the plane is very long and the motor cowling is extended well beyond the front of the engine. In such a case, it is necessary to add a supplementary lenthener to the initial spacer.
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11°) What maintenance precautions are necessary in order to ensure my new DUC propeller is kept in perfect condition for me to continue using it for many years while maintaining its original efficiency?

DUC propellers are high technology products and, as a consequence, require attention which is comparable to the performances that is expected from them. It is important that, as for all aviation equipment, regular visual inspections be made of each of the propeller components in order to ensure tightness of the screws and to check that no part is loose or delaminated. It is also essential to check for signs of impact and other damage.
In general, it is the leading edge which is most likely to incur degradation over the course of time through abrasion and/or by minor impact incidents. You can pass your hand over the leading edge to determine if it is damaged. It is recommended that you clean the propeller daily, after each flight, with a cloth which is dampened with the recommended cleaning fluid Ref. 01-80-003 in order to make sure that the blades are always clean. In this way, your propeller will remain ready for use and will continue to provide you with the best performance for your future flights.
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12°) Can I paint DUC Carbon Fiber products?

Yes you can but it is not advised as experience shows that due to air abrasion paint doesn't stand the time. However if you wish to apply some paint you need to use Polypropylene paint.
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13°) Can I fit a hub directly onto the propeller shaft or do I always need an adaptor?

For a Jabiru engine, you always need an adaptor.
For a Rotax engine, you can bolt the hub directly onto the propeller shaft, you must make sure that screws don't withstand shear forces. In no case should threading protrude inside the hub. The head screws shall be of the right length so that the screws are screwed home. Incorrect installation may result in the loss of propeller during flight.
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14°) What is better, a 2 blade or a 3 blade?

A propeller blade works like an aircraft wing: its profil is made of its corde and its incidence. To define the number of blades and the diameter of a propeller, the mandatory parameters are:

• The engine power
• The propeller rotation speed, that depends on the engine if direct transmission or reduction gear box ratio
• The aircraft glide ratio (aerodynamic efficiency)

All these parameters give a blade pitch that must be compatible with the aircraft performances (fast or slow plane)
Example:

1. For a given engine power, the highest the propeller rotation speed the highest the propeller thrust. As a result, it is possible to reduce either the number of blades or the propeller diameter. Conversely, the slowest the propeller rotation speed the lowest the propeller thrust. As a result it is necessary to increase the number of blades.
2. For a given propeller rotation speed, if the engine power is low then either the number of blades or the diameter has to be reduced. Conversely, if the engine power is high, the number of blades has to be increased.

To make it even more complex, these parameters are not the only one to be considered: the aircraft glide, its weight etc. are also to be considered. Consequently, the definition for the number of blades required for a propeller being complex, it is not possible to assert that a 2 blade propeller will give better results than a 3 or 4 blade propeller (or even 5 blade for the ANIBAL propeller).

• The blade n°1 progresses following the green spiral
• The blade N°2 progresses following the blue spiral
• The blade N°3 progresses following the red spiral

You can see on this drawing that each spiral is independant and that in no case they can meet each other. Consequently, any one blade can't be disturbed by the air flow of the other blades.
The propeller must be tailored to the exact specifications of each aircraft. This is why DUC is offering so many different models in standard and is designing specific models upon request for aircraft manufacturers seeking the best possible performance for their aircraft.
This explains why from one brand to another, for the same engine, we can have a different number of blades. The number of blades is defined by the lift of the blade and its length (the chord has a big influence). For a Swirl blade, we combine 2 parameters: narrow chord and constant speed effect. As a result, in some cases for the same installation we may advise one more blade than another brand. We have done extensive tests on a J400 Jabiru 6 cylindres, and we could test the 2 diameters (1520mm/60’’ and 1620mm/64’’). The best comprise was achieved with the 1520mm/60’’ propeller (the more we reduce the diameter the more we give advantage to the cruise speed, we reduce slightly the performances in takeoff and climb) and the other way round if we increase the diameter. Therefore in standard atmosphere we advise the 1520mm/60’’. However, air heat can penalize a great deal small diameters. If the plane is going to fly in a warm climate, it is advisable to go for 1620mm/64’’
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15°) I am going to place my order, how long before delivery?

DUC is offering in standard a lot of different models to provide the best performances to a wide range of aircraft around the world:

• 3 designs: Windspoon, Swirl and Flair
• 3 structures: Normal, Reinforced and Super Reinforced
• 2 leading edges: Carbone or Inconel
• 2 motions: Clockwise or aniclockwise (for most of the models)
• Many diameters for the Swirl: from 1400mm to 1745mm
• 2 Logo colours: Gold and Silver

That's approximately 90 models available.
Love4aviation is holding permanently a stock of 30 different models for international market. If at time of order your model is in our stock, you will receive it within 5 working days. If your model has to be manufactured upon order, you will receive it within 6 weeks. An order is a firm order only when payment has been received.
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16°) Is the Turbo Spinner adapted for any aircraft and engine?

The Turbo Spinner improves engine cooling during ground manouvres and climbing. Consequently the engine temperature range is reduced, avoiding thermal shock. As a result it improves the engine's lifetime and reduces engine's failures on ANY type of engine. The Turbo Spinner efficiency is going to be more obvious with direct drive propellers i.e: Jabiru engines.
The only restriction is on the engine cowling: The air intakes must be positioned close to the propeller shaft, see picture below. A Fly Synthesis Stork for example is well suited for a Turbo Spinner, especially if fitted with a Jabiru engine (in which case the Turbo Spinner should come in standard). Most of the Tecnam and Fly Synthesis are well suited for a Turbo Spinner.


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17°) How many different models are available?

By chosing a Duc propeller, you have the guarantee to get the exact model of propeller that will give optimum results for the precise specifications of your combinaison of aircraft+engine.
Duc is using a modularity concept that allows you to receive a propeller tailored to your needs and to your budget.
DUC is offering in standard a lot of different models to provide the best performances to a wide range of aircraft around the world:

• 3 designs: Windspoon, Swirl and Flair
• 3 structures: Normal, Reinforced and Super Reinforced
• 2 leading edges: Carbone or Inconel
• 2 motions: Clockwise or aniclockwise (for most of the models)
• Many diameters for the Swirl: from 1400mm to 1745mm
• 2 Logo colours: Gold and Silver

That's approximately 90 models available.
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18°) What is Anodized Aluminum?

Many metals are structurally weakened by the oxidation process, but not aluminum. Aluminum can actually be made stronger and more durable through a process called 'anodizing'. Anodizing involves placing a sheet of aluminum into a chemical acid bath, quite often acetone in laboratory experiments. The sheet of aluminum becomes the positive anode of a chemical battery and the acid bath becomes the negative. An electric current passes through the acid, causing the surface of the aluminum to oxidize (essentially rust). The oxidized aluminum forms a strong coating as it replaces the original aluminum on the surface. The result is an extremely hard substance called anodized aluminum.
Anodized aluminum can be nearly as hard as diamond under the right anodizing process. Many modern buildings use anodized aluminum in places where the metal framework is exposed to the elements. Anodized aluminum is also a popular material for making high-end cookware such as frying pans and pots. Heat is distributed evenly across anodized aluminum, and the process of anodizing provides a naturally protective finish. It is possible to use another electroplating process to make anodized aluminum look like copper or brass or other metals. Special dyes can also be used to color the anodized aluminum for decorative uses.
Because of its strength and durability, anodized aluminum is also used in a number of other applications. Many of the satellites circling the Earth are protected from space debris by layers of anodized aluminum. The automobile industry relies heavily on anodized aluminum for trims and protective housings for exposed parts. Furniture designers often use anodized aluminum as the framework for outdoor pieces as well as the base metal for lamps and other decorative items. Modern home appliances and computer systems may utilize anodized aluminum as protective housing.
Anodized aluminum may not be appropriate for all applications because of its non-conductive nature. Unlike other metals such as iron, the oxidation process doesn't seem to weaken aluminum. The layer of 'aluminum rust' is still part of the original aluminum and will not transfer to food or easily flake off under stress. This makes it especially popular for food-service applications and industrial applications where durability is crucial.
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19°) A Rotax 2 stroke Rotax can have 5 different gear box reduction: 2,58 - 2,62 - 3 - 3,47 - 4. How that influences the choice of the propeller?

Many parameters influence the choice of a propeller, but one of the most important is the rotation speed, thus the reduction. This plays a prominent role, more important than engine's power. The table below provides the general rule.
• Contact us to discuss your needs

Reduction	Propeller	Diameter
2,58	2 blade Swirl	1660mm - 66"
2,62	2 blade Swirl	1660mm - 66"
3	3 blade Swirl	1740mm - 69"
3,47	3 blade Windspoon	1730mm - 68"
4	3 blade Windspoon	1730mm - 68"

 

• Gearbox type B can have 3 different ratio: 2-2.24-2.58
• Gearbox type C can have 4 different ratio: 2.62-3-3.47-4
• Gearbox type E can have 4 different ratio: 2.62-3-3.47-4

The reduction ratio is engraved on the housing that closes the gear box.

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• Rotax 80hp, Reduction 2.27 gives 2500 RPM for the propeller
• Rotax 100hp, reduction 2.43 gives 2300 RPM for the propeller
• Jabiru 80hp has no gear box, the propeller's speed is therefore 3200 RPM

• 1740mm -  69" for Rotax 100hp
• 1660mm - 66"  for Rotax 80hp
• 1520mm -  60" for Jabiru 85hp (or 2 blade 1620mm - 64") The 3 blade offers better ground clearance, better aerodynamic balancing and less noise. The 2 blade is less expensive and lighter. Differences are marginal though. Performances are the same (climb and cruise). Some people prefer the look of a 3 blade and others the look of the 2 blade.