ST is not the major problem. Lose hydraulics on a 350 and you will be as busy as can be.
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Simulated Hydraulic failure
(
Except EC 130 B4 & AS 350 B3 equipped with the optional dual hydraulic system):
- In steady flight conditions, simulate the hydraulic failure by depressing HYD TEST push button on the
System Control Unit (
Honeywell or SCU console panel): HYD + Gong sounds to be able to achieve Vy,
CAUTION
: The Instructor must insist to obtain speed reduction before the HYD cutting off.
- The intensity and direction of the control feedback force will change rapidly. This will result in a loss of
control,
- Control loads increase with speed. As control loads increase, be careful not to inadvertently move twist
grip out of FLIGHT detent,
- If necessary during the training exercise, hydraulic assistance can be recovered immediately by setting
back HYD TEST pushbutton to OUT position or by switching back the hydraulic cut-off switch to ON,
- If the HYD TEST pushbutton is not reset on the SCU, no hydraulic assistance can be restored. After
hydraulic cuts off with the switch on the collective lever, do not forget to switch off the HYD pushbutton on
the console.
- Once safety speed set, reset HYD TEST pushbutton to restore hydraulic pressure in tail rotor
accumulator (AS 350 B2/B3).
On previous versions of AS350 equipped with a HONEYWELL console control, do not silence the HORN
by using the HORN switch.
The HORN will be silenced when the pilot selects the hydraulic cut-off switch to off.
If the pilot uses the HORN switch to silence the HORN before using the hydraulic cut-off switch, this
crucial step could be forgotten. This could then result in significant unbalanced lateral cyclic feedback
forces, especially at low speed, if one of the lateral accumulators depletes before the other one.
In addition, de-activating the HORN using the HORN switch, makes it unavailable to warn the pilot of low
or high rotor RPM.
Pay attention to the following:
- Hydraulic accumulators gives energy during approximately 20 seconds, so reduce to safety speed
in this time delay,
- Do not accelerate after switching OFF the hydraulic cut-off,
- Anticipate to perform a shallow approach,
- Perform a running landing,
- Hover flight or any low speed maneuver must be avoided,
- Keep in mind that All Up Weight increase risks of aircraft control loss at low speed,
- The statistics show that a non strict compliance with the procedure increases the level of risk in a
consequent way