S-92 - 13 - HYDRAULICS

What systems are driven by the #1 Hydraulic System?

#1 SAS #1 T/R Servo #1 M/R Servos

What systems are driven by the #2 Hydraulic System?

#1 SAS #1 T/R Servo #1 M/R Servos Boost

If the #2 hydraulic system has a leak prior to the tail rotor shutoff valve, will there be any degradation of flight control?

#1 and #2 are routed through a heat exchanger. Half of each system passes through each fan without mixing so that 1 fan may cool both systems in the event of a fan failure. The #3 system is not cooled by the fan and does not require cooling.

What systems are driven by the #3 Hydraulic / Utility System?

#3 Hydraulic / Utility Landing Gear APU Accumulator Cargo Ramp

Should the # 1 or # 2 hydraulic pumps fail, what is the back-up system?

#3 Hydraulic / Utility System

What systems are affected by WOW?

LDI IBIT, TCAS, WX Radar FSTBY, under-frequency protection, landing gear control valve, hydraulic ground checkout pump, AFCS, CVR/FDR, Maintenance pages on MFD's and RTU's, APU fault/fail logic, transponder, ECS, Engine Out and Low Rotor aural alerts.

What causes a HARD LANDING caution to illuminate?

Landing in excess of 480-720 FPM (approximately 3G's) sensed by one of the accelerometers mounted at the top of each landing gear shock strut.

How may a pilot or crew member manually lower the ramp in the event of a #3 hydraulic system failure?

Manually release on the ramp control valve.

What is normal hydraulic system pressure?

3500-4200 PSI (4000)

What speed limitation is associated with the emergency extension?

90 KIAS

Five independent hydraulic systems.

1. #1 Hydraulic System 2. #2 Hydraulic System 3. #3 Hydraulic / Utility 4. Wheel Brakes 5. Rotor Brake

What conditions cause the landing gear warning, "TOO LOW, GEAR"?

Below 150 feet and 60 KIAS.

How is the nose wheel of the tricycle landing gear controlled on the ground?

Differential braking and tail rotor thrust.

What electrical buses power the landing gear controls?

Essential Battery (Relevant for Triple Converter Failure)

If the #2 hydraulic system has a leak past the tail rotor shutoff valve, what caution segments and system pressure will be observed in the cockpit?

HYD 2 RSVR LOW TR SRVO PRES Normal system pressure, no degradation of control.

If the #2 hydraulic system has a leak prior to the tail rotor shutoff valve, what caution segments and system pressure be observed in the cockpit?

HYD 2 RSVR LOW TR SVO PRES MR SVO PRSS HYD 2 PUMP FAIL SAS 2 PRES BOOST PRES Boost is no longer available so control forces will be heavier, but the helicopter fully controllable.

What temperature limits apply to the hydraulic system?

HYD TEMP ALERT at 110 C HYD TEMP LIMIT at 135 C

Where is the hydraulic reservoir for the brake system located?

In the cockpit on the #1 side console forward side.

Is there a self-centering device in the nose gear assembly that will center the nose gear from any position upon lift off into the hover.

NO - 180 degrees out the nose gear will not center.

What is the emergency method to lower the landing gear?

Nitrogen blow down system.

If one hydraulic system loses pressure, can the other be shut off?

No, an electrical interlock will prevent the disabling of a 'good' system in this scenario.

If the #3 hydraulic pump fails in flight, what functionality of the system is lost? Is any functionality restored upon landing?

Normal gear extension APU Accumulator recharge ramp operation are not possible. Upon landing, the ground pump will provide hydraulic power for the APU Accumulator and Ramp operation.

During normal start and shutdown of the helicopter, at what Ng / Nr speeds do the Back-up isolation valves close and open?

On start, isolation valves close at 15% Ng and re-opens at 50% Nr. On shutdown, they close at 50% Nr and re-opens at 15% Ng after 2 minutes.

What effect does moving the gear handle have on hydraulic system pressure?

Pressure will increase from depressurized mode of 2000 +/- 1000 to high mode of 4000 psi.

Describe the preflight procedure for checking brake pad wear.

Set the parking brake and observe that the wear indicator pins (2 per main wheel) are extended beyond the brake assembly.

What is the function of the brake system slave valve?

The brake system slave valve directs pressure from the master cylinders to the brake pads and prevent pressure from entering the opposite master cylinder. The slave valve also resolves pressure from both pilot and copilot brake pedals and allows the pilot applying the most pressure to control the brakes.

There are "__" main rotor servo actuators mounted on the main gear box.

There are "3" main rotor servo actuators mounted on the main gear box.

Why do the Back-up isolation valves open / close (15% Ng / 50% Nr) during normal start and shutdown of the helicopter?

This prevents transfer of hydraulic fluid from the #3 system to the #1 or #2.

What conditions must exist to perform the LDI test?

WOW Rotor brake on AC power

If the #2 hydraulic system has a leak past the tail rotor shutoff valve, when will LDI be activated?

When the HYD 2 RESVR LOW caution is set.

Does the hydraulic system have a filter bypass capability in the even of a clogged filter?

Yes, but only on the return side to prevent hydrostatic lock.