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ZI aerodrome Sisteron
04200 VAUMEILH - France
Phone : +33 4 92 34 00 00
Phone reception opened from Monday to Friday
From 9 to 12 a.m and 2 to 4 p.m.
The best way to reach us is by email :

Annual closure : from 1st to 16th August 2020

E-PROPS : Extended Hubs / Integrated Spacers

In leisure aviation, there are not large series as in the automotive industry. Aircraft manufacturers are used to change somes details on their aircraft, and particularly engines covers. Sometimes the engines come outside the covers, and sometimes are inside. It depends on the versions, and it is impossible for propellers manufacturers to know all versions of all aircraft.

Usually propellers manufacturers propose aluminium spacers if the engine is inside the engine covers, in order to space the propellers from the engine fairings.
The E-PROPS solution is lighter, stronger, more secure and cheaper.

E-PROPS has developed an innovative system to replace the usual spacers in aluminium (heavy, expensive and difficult to assemble) : EXTENDED HUBS / INTEGRATED SPACERS.

1- Extended hub V20 range
2- Extended hub V12 range
3- Does your aircraft need an extended hub ?
4- Length of extended hubs : measures

1- Extended hubs V20 range

E-PROPS V20 hub
Hub DURANDAL-3 V20 : 3 parts full carbon

click on the video to discover the V20 extended hubs

E-PROPS hubs
38 different lengths : from -20 to +170 mm in 5 mm steps

2- Extended hubs V12 range

Extended hubs V12 range are made of 1 piece integrated with the hub.
Here is a presentation of these hubs:

presentation video


- Weight reduction
weight of the V12 spacer (carbon extended hub) = 3.5 gram * Se in mm (including screws)
it means 3.5 gr/mm
To be compare with 20 gr/mm of a usual aluminium spacer (with screws)
Example for the spacer of a Savannah ultralight :
- weight of an E-PROPS extended carbon hub, length 115 mm (including screws) = 0,4 kg
- weight of an usual aluminium spacer, length 115 mm (including screws) = 2,4 kg
it means a reduction of 2 kg !

- Less weight on the gear box
A too big weight hanged to the gear box is reducing its lifetime.
The heavy propellers generate a significant risk of breakage of the gear box.
Reducing the weight of the spacer allows to limit this risk.

- Lower cost
The extended hubs are at the same price as the standard hubs.
No need to buy a spacer in addition. Considerable savings !

- Less vibrations
With an extended hub, the propeller centering is direct. No need of spacers and screws stacks, which can generate vibrations.
A very simple system strongly reduces vibrations risks.

- A reliable and durable system
The E-PROPS hubs, standard or extended, are extremely strong.
Material : 100% carbon + epoxy resin high T°
Injection with RTM process (Resin Transfer Molding)
Compact hub for minimum drag and to optimize engine's cooling.
No life limitation. Recommended major periodic inspection : 2.000 hrs

- Simple assembly and reduction of the parts number

E-PROPS hubs

A : 6 Screws + 1 central nut (for the central screw of the hub)
B : 7 Nord-Lock washers
C : Flange in anodized aluminium
D : Upper Half Hub
E : Lower extended Half Hub
F : Option : 5mm counterplate to adjust the length of the hub (a 5 mm step)
G : Reducer flange (part of the engine)
H : 6 Rotax drive lugs (threaded)

3-blade propeller with extended hub : 3 blades, 2 half hubs, 1 aluminium flange, 7 Nord-Lock washers, 6 screws, 1 nut
=> It means 20 parts
3-blade propeller with aluminium spacer : 3 blades, 2 half hubs, 1 aluminium flange, 7 washers, 6 screws, 1 nut , 1 aluminium spacer, 6 drive lugs for spacer, 6 washers, 6 nuts, 6 screws and 6 washers for spacer.
=> It means 51 parts
The "Extended Hub" solution allows to reduce of 61% the number of parts necessary for the propeller's assembly.

E-PROPS hubs
hub with integrated spacer 115 mm (for Savannah, for example)
and on the right with a 250 mm spinner

Lengths available : from 0 to 115 mm, on 5 mm increments

E-PROPS hubs
some examples of E-Props extended hubs

3- Does your aircraft need an extended hub ?

Sometimes it is necessary to have a spacer between the propeller and the reducer flange, whan the engine is far inside the engine cover.

It exists 3 configurations :

A) the gear box side plate is outside the engine cover
=> you don't need any spacer. Please indicate He = 0 in your order.

B) the gear box side plate is just at the edge of the engine cover
=> you don't need any spacer. A 5 mm spacer is usually enough to space the propeller from the engine cover.
A picture of your present propeller assembly, taken above the engine and from the side, could help the E-PROPS team to see if a 5 mm spacer is necessary.

C) the gear box side plate is outside the engine cover
=> you need a spacer. An extended hub as proposed by E-PROPS is a very good solution : light, strong and cheap.
To know which extended hub, please see § 4.

Please note :
If your aircraft need an extended hub and if you want a spinner, you must have a spinner assembled by front of the propeller. If your spinner is assembled between the propeller and the gear box side plate, il would not be possible to use it, because the extended hub is a one-piece carbon part, and it is prohibited to cut it (see § 5).

In this case, you have 3 solutions :
- you order a complete set : E-Props propeller + extended hub + standard spinner.
- you take a mini-spinner (diameter 130 mm), which is available for each E-Props propellers, tractor or pusher. Simple, very light and cheap solution.
- you order an E-Props with a standard hub, and you keep the aluminium spacer you already had before, and your spinner. You just have to check : first, if your spacer has a drilling patern 6M8d101,6 ("big" Rotax drilling patern), and then if your spinner is a 3-blade model. You probably woud had to adjust your own spinner, so E-PROPS does not recommended this solution.

4- Length of extended hub and spinners : measures

To order an extended hub, you just need to take a measure. It is very simple.
Procedure :
- remove your current propeller and all its accessories, particularly the aluminium spacer if any
- put the engine cover back
- take two metal rulers : one to be put between the 2 external sides of the engine cover, the other to measure
- out the ruler 1 against the engine cover, in front of the gear box plate, where will be the propeller
- put the ruler 2 perpendicularly to the ruler 1, side which measured staying visible
- note the measure M as on the picture below
- then add between 5 mm and 10 mm to this measure M to define the thickness of the extended hub which necessary to your aircraft. 5 mm or 10 mm : it depends if you prefer to have the propeller close or far from the engine fairings. Be careful to keep enough place to dissamble the covers. See below.

E-PROPS hubs

In case of mistake on the M measure (length of the spacer) :
- we can change the extended part of the hub
- please indicate the length you want
- on range V20, we send the good spacer
- on range V12, we change the extended hub, and we balance the propeller again with the new extended hub (please send the whole propeller back to us)

NEVER cut an E-PROPS extended hub.
The extended hubs are designed and manufactured for a defined length.
Cut them is similar to destroy the mechanical strength of the hub. This would be very dangereous.
It is absolutely FORBIDDEN to fly with an E-PROPS extended hub which would have been cutted.

E-PROPS hubs
extended hub on a ROTAX's reducer with a spinner

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