FES Propeller Manual Version 1.21 April 2019
Page 10 of 11
7. Fix the spinner with four Inox M4x8mm countersink head screws, and two M4x6mm
screws. Two screws which are 2mm shorter are located at 60deg and at 300deg
angle (upper left and right). Tightening of all 6 screws should be gently with small
torque (do not use high torque, as thread in the aluminum plate could be damaged).
Please do not use any glue to secure them, as during rotation centrifugal force to the
screws create high enough friction, which prevent unscrewing. We prefer to cover heads
of the screws with white round stickers (diameter about 14mm), which additionally secure
the screws from unscrewing, and it also looks nicer!
7. Operating instructions
To ensure reliability and safety of the propeller, preflight check of the propeller should be
done before each flight by the pilot/owner:
- remove protection fluorescent fabric cover (optional equipment).
- make sure that propeller surfaces are clean before each flight. Propeller full of bugs
is less efficient and in worst case they can even increase level of vibrations. For
cleaning, use wet cloth as used for other parts of the glider.
- check visually the leading and trailing edge at the root. If there are visible any
cracks or other major damages, please contact manufacturer for advice before next
flight. If is not clear, please check next chapter about acceptable minor damages.
- check that each blade is opening and closing freely with only small friction. If there
is too much friction, it is necessary to clean and lubricate the attachment bolts and
bushing. To perform this is necessary to remove the propeller blades.
8. Acceptable minor damages
1. Thin cracks up to 10 mm of length in paint are allowed, but not in the root section. Only
in the outer part of the propeller blade (15 cm or more from attachment point) such cracks
in paint are acceptable. If such cracks do occur, it is anyway advisable to consult with
qualified service or manufacturer regarding airworthiness. Please send a good photo and
information about operating time.
2. Only small damages of the paint on the leading edge are acceptable, as they are
unavoidable after long time of usage.
3. Structural cracks, deformations or de-laminations of composite structure are not
acceptable for the propeller blades. If they occur, please send propeller blades to
manufacturer for the inspection.
