Pilot Operating Handbook
H3 EasyFlyer Sport
SECTION 7
SYSTEMS
Dynali_POH_H3 EasyFlyer Sport Rev. 2.5
– Issue date 30.10.2020 Page
55
7.4
MAIN TRANSMISSION GEARBOX (MTG)
The main transmission gearbox
transfers the rotating movement from the main
transmission shaft to the main rotor mast
. The MTG of the H3 is
dimensioned to
support 250 HP
whereas in reality it only has to bear a maximum of 115 HP. The total
weight of the assembled MTG is 15kg.
The MTG contains conic gearing with spiral teeth providing a single stage of reduction.
The gearings are fabricated from aviation quality steel which is thermally treated and
lubricated in a mineral oil bath
. The large upper bearing in the main transmission
gearbox may leak a little. This is not a problem as all precautions have been taken :
sponge clean and watch the oil level. No intervention is required as long as the lip of
the bearing flange fills up clearly.
The MTG is equipped with a T° sensor and with a chip detector, wired to a
warning light in the cockpit, which indicates the pilot of every metallic particle
detected.
The conical spiral gearing of the main transmission gearbox is a part that wears out
rapidly. The gearbox should be emptied every 50h to filter the oil or renew it and also,
the magnetic plug should be surveyed.
Every 250h, the main transmission gearbox should be opened in order to inspect the
conical gear and the bearings.
7.5
MAIN ROTOR
The rotor mast is
made of Cr-Mo steel
and designed to bear a load of +22G.
The blades are made of
extruded high resistance aluminum
. As a safety precaution,
their service life is provisionally limited to 500h before complete inspection.
They can
be used in all weather condition
. A mark is traced on the upper side of the blade to
check for possible permanent elongation of the blades. They are held by stainless steel
sheets and aluminum blade roots.
In option, carbon blades can be installed. They have no theoretical lifetime limit
but
their use must be limited to day VFR fair weather conditions only. They can
be damaged if flown under rainy, dusty or hail condition.
Four stop bearings with oblique contact allow for the blade root to oscillate to set the
pitch.
They are over-dimensioned and can support excess speed up to 600RPM.
These bearings oscillate very little and the bearing balls, over the long term can make
traces in their seating, causing shimmy in the cyclic pitch control. They should be
replaced as soon as the shimmy can be strongly felt.
The ball joints of the blade rods have a little play ; they should be greased with
traditional grease.
