Pilot Operating Handbook
H3 Sport 135 HP
SECTION 7
SYSTEMS
Dynali_POH_H3 Sport 135 HP Rev. 3.3 – Issue date 15.01.2021 Page
65
The tension in the drive belts is provided by the two tensioning rods linked to the
tensioner arm. An electric actuator moves the bell crank of the tensioner arm for
tensioning the belts.
The clutch system of the H3 is commanded from the cockpit. It serves to connect or
disconnect the engine to the transmission system. When disconnected, it allows the
engine to start with the rotor stationary, ensuring the safety of those on the ground
during warm-up. Once ready for take-off, the rotor is engaged by the pilot using a
switch on the instrument panel.
The V-belts are slotted for better power transmission. Adequate tensioning is
mandatory. The adequate tension can be easily checked before the flight with a spring
dynamometer. The belts may not flap, this can cause premature wear of the freewheel.
Correct belt tensioning = 15 kg for 1 cm deflection in the middle of the belt.
The transmission shaft transmits the movement forward to the main rotor via the main
transmission gearbox and to the tail rotor via a rubber coupling joint and then to the
rear transmission.
The long shaft which drives the tail rotor is supported by seven intermediate bearings
in the tail tube.
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 135 HP. The total
weight of the assembled MTG is 15 kg.
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 :
Summary of Contents for H3 Sport 135 HP
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