FES Propeller Manual, Version 1.21
September 2020
Page 6 of 10
4. Construction
4.1 Certification standards
Propeller type FES-DIS-P1-102 described here is designed and tested according to
CS 22 Subpart J.
This manual is intended to comply with CS
‐
22.1903, providing the essential
information for installing, servicing, and maintaining the propeller.
4.2 Construction Material
Propeller blades are made of CRFP (carbon fiber reinforced plastic). They are
produced in accurate metal molds, which were manufactured using modern CNC
technology. This made it possible, to have very accurate profile geometry. At attachment
point of propeller blade is integrated hardened steel bushing with very accurate tolerance,
so that play is minimal.
Propeller hub is CNC milled part, from Aluminum alloy 7075,
black anodized.
4.3 Surface finish
High quality acrylic white paint (PPG D700) is used to protect the composite body
against moisture and erosion. Each blade pair is sanded and polished so that mass
difference is only about 0,1g (0,3g is maximum weigh difference tolerance). Paint is
resistant against fuel, oil and other chemical products. This type of paint has also an
excellent flexibility. Only tips of the propeller blades can be painted in other colors as a
safety mark. Otherwise only allowed color is white as this is structural part.
5. Removal of propeller blades
1. Carefully remove white round stickers which are glued over 6 screws, which hold the
spinner. Unscrew all 6 M4 countersink screws, with 2,5mm sized hex key, to remove the
spinner. Note that 2 screws are 2mm shorter!
2. Before start of propeller blades removal it is strongly recommended to close motor
openings with a tape, as show on photo above in order to reduce possibility that any of
the small parts could enter into the motor, if it falls through the fingers by coincidence. If
this would happen, it is usually necessary to remove and open motor, which is quite
demanding job, so it is better to tape openings.
Flatten and remove split pin, which secure M8 crown nut on each end of propeller blade
attachment bolt. Carefully unscrew crown nuts, and remove M8 spacers
3. Push attachment bolt out of the hub. If is not possible to push them out with hands,
you can use small plastic or wooden hammer and carefully push them out completely.
Propeller blades are then free to take out.
6. Installation of propeller blades
1. Before installation of new propeller blades, check that marking on the label, which is
located on lower inner surface, confirms the correct type. For Discus 2c FES, propeller
type is FES-DIS-P1-102. Left blade is marked as A and right blade is marked as B.
