FLIGHT MANUAL
DYNALI HELICOPTER COMPANY
Edition N°3
DYNALI H2S January 2012
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26
2.16.
LIMITATIONS ON LANDING ON SLOPES
Forwards (i.e. tail downhill) ................................................................................ 15°
Lateral right (i.e. bottom of the slope on the right) .................................... 10 to 12°
Lateral left (i.e. bottom of the slope on the left).................................................... 8°
Note : these conditions should be avoided as far as possible. Prefer landing at 45°. (see
below)
Backwards (i.e. tail uphill) .................................................................. PROHIBITED
Note : when obliged to land on sloping ground, always try to land at 45° to the axis of the
slope. You will reduce the risk of dynamic rollover.
2.17.
LIMITATIONS TO LOAD FACTOR (mast bumping)
AS WITH ALL TWO BLADE ROTOR HELICOPTERS, THE DYNALI H2S CAN NOT FLY
WITH A ZERO OR NEGATIVE LOAD FACTOR AS THIS CAN RESULT IN A
CONFIGURATION WHICH CAUSES MAST BUMPING.
The rotor flap is only (relatively) stable when its centre of gravity is lower than the axis of its
teetering hinge.
Furthermore, under a low or negative load factor, the helicopter is still pushed laterally by the
tail rotor and rolls over even faster on account of its low mass.
Mast bumping only occurs on twin rotor blade helicopters. It occurs when the load factor
moves from a level of +1G towards 0G. It is initiated as from +0,5G.
Mast bumping starts with a loss of lateral control of the helicopter from the thrust of the rear
rotor and may end with the fracture of the rotor mast.
! AVOID ALL SUDDEN TRANSITION FROM HORIZONTAL FLIGHT TO A DIVE BY
PUSHING THE CYCLIC FORWARD OR SUDDEN TRANSITION FROM CLIMB TO
HORIZONTAL FLIGHT.
! IN GENERAL AVOID ANY STRONG, SUDDEN CYCLIC MOVEMENTS IN LOW G
CONDITIONS AS THIS MAY PROVOKE PARTIAL WEIGHTLESSNESS (REDUCTION OF G
FORCES); IF A ROLL STARTS AT THAT TIME, PULL BACK GENTLY ON THE CYCLIC IN
ORDER TO REDUCE THIS LOSS OF G (which is the equivalent to re-loading the rotor)
BEFORE CORRECTING THE ROLL.
Note : during the instruction period, mast bumping will be studied in theory with the instructor
on the ground only.
