Oil

The oil system provides storage, distribution, cooling, and indication of oil for the lubrication of the engine. It consists of the following systems:

• Oil storage

• Oil distribution

• Oil indicating

Oil storage

The oil storage system stores oil in a sufficient quantity for lubricating the engine and cooling the engine oil. It consists of the oil tank assembly.

Oil tank

The oil tank assembly is located on the forward firewall outside of the engine compartment. It is made from welded and formed aluminum sheets with integral mounting flanges. It has a filler neck with a threaded cap, a threaded sight glass and an integral scupper with a drain hose to avoid oil spills inside the oil tank assembly compartment. It has threaded fittings for connecting to the oil distribution system.

Operation

The oil tank assembly contains the engine oil. The operator checks the oil level through the sight glass. The operator fills the oil tank assembly with oil through the filler neck, the integral scupper prevents spillage inside the compartment. The oil is gravity fed to the engine Reduction Gearbox (RGB) through the outlet fitting. The oil returns in the oil tank assembly through the inlet fitting. The pressure inside the oil tank assembly is equalized through the vent fitting.

Oil distribution

The oil distribution system distributes the oil to the engine and to the oil cooler. It also cools the oil.

It consists of the following components:

• Oil cooler

• Inlet line

• Pressure line

• Return line

Oil cooler

The oil cooler is located in the aft fuselage below the tailboom attaching points. It is a combined engine and transmission oil liquid to air heat exchanger. A blower driven by the tail rotor driveshaft forces air through the oil cooler. Refer to, Fan shaft assembly for the description of the blower and the tail rotor driveshaft.

The oil cooler is a black powder coated assembly made from welded and brazed aluminum plates and bars. It also includes the union fittings at each port of the oil cooler and the ducts from the blower.

Inlet line

The inlet line is located between the oil tank assembly and the engine oil inlet. Refer to Oil tank for details on the oil tank assembly.

The inlet line consists of the elbow fitting that connect to the oil tank fittings below the oil tank, a flexible hose assembly, and the inlet fitting of the engine Reduction Gearbox (RGB). It feeds the oil from the oil tank assembly to the engine RGB.

Pressure line

The pressure line is located between the engine RGB and the oil cooler and passes through the horizontal firewall. It consists of the outlet fitting of the engine, a flexible hose assembly, a fitting on the horizontal firewall, and another flexible hose assembly at the inlet of the oil cooler. It routes the hot oil under pressure from the engine to the oil cooler.

Return line

The return line is located between the oil cooler and the oil tank assembly on the right side of the truss assembly. It consists of a metallic tube assembly at the outlet of the oil cooler that is fastened to the side of the truss assembly, an union fitting, and another metallic tube assembly at the inlet of the oil tank assembly. It routes the cooled oil to the tank assembly.

Operation

The oil from the oil tank assembly is gravity fed to the inlet fitting of the engine RGB through the inlet line. The pumps inside the engine RGB circulate the oil in the engine to lubricate its internal components, the engine also has the filter and the oil indicating components. Refer to the engine manufacturer’s maintenance manual for details about the engine and its mounted components.The hot oil exits the engine RGB by the outlet fitting and is fed under pressure to the inlet of the oil cooler through the pressure line. The oil is cooled inside the oil cooler and exits from its outlet. The cooled oil is routed back into the oil tank assembly through the return line.

Oil indicating

The oil indicating system provides an indication of the status of the oil system. It consists of the engine mounted chip detectors.

The engine chip detectors are located in front of the engine on the engine Reduction Gearbox (RGB).

Operation

The +12 VDC TRANSDUCER POWER OUT output of the GEA is shared between the two chip detectors.

The +12 VDC TRANSDUCER POWER OUT from the GEA is applied to pin 2 of the chip detector ENG 1, through the internal resistance of the chip detector out of pin 1 and through the resistor to the SIGNAL GROUND input of the GEA. The voltage developed across the resistor is sensed at the ANALOG IN 5 HI and ANALOG IN 5 LO inputs of the GEA, during normal operation this voltage is about 5 VDC. When the chip detector detects a metal particle, pins 1 and 2 are effectively shorted and the full 12 volts DC is sensed by the ANALOG IN 5 inputs. This generates the CAS caution message ENG CHIP and advisory message ENG CHIP 1. A voltage of less than 4.89 VDC across the ANALOG IN 5 inputs of the GEA indicates a fault of the chip detector or wiring. This generates the CAS caution message ENG CD INOP and advisory message ENG CD 1 INOP.

The +12 VDC TRANSDUCER POWER OUT from the GEA is applied to pin 2 of the chip detector ENG 2, through the internal resistance of the chip detector out of pin 1 and through the resistor to the SIGNAL GROUND input of the GEA. The voltage developed across the resistor is sensed at the ANALOG IN 4 HI and ANALOG IN 4 LO inputs of the GEA, during normal operation this voltage is about 5 VDC. When the chip detector detects a metal particle, pins 1 and 2 are effectively shorted and the full 12 volts DC is sensed by the ANALOG IN 4 inputs. This generates the CAS caution message ENG CHIP and advisory message ENG CHIP 2. A voltage of less than 4.89 VDC across the ANALOG IN 4 inputs of the GEA indicates a fault of the chip detector or wiring. This generates the CAS caution message ENG CD INOP and advisory message ENG CD 2 INOP.Refer to the engine manufacturer’s maintenance manual for details on the engine mounted components.