Drivetrain and Rotors Flashcards by Jonathan Duke

What are the locations of the transmission chip detectors?

Upper main gearbox, lower main gearbox, freewheel unit, tail rotor gearbox.

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How many chip detectors are there in the transmission system?

Four (Two in the main gearbox, one in the freewheel and one in the tail gearbox)

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Which two components does the KAflex drive shaft connect?

Freewheel unit and main gearbox.

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What are the four main advantages of the KAflex drive shaft?

Does not require lubrication.
Fails safe - continues to provide drive after failure.
Provides pilot feedback of failure (vibration).
Accommodates transmission movement (flex and length change)

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What type of mount is used to secure the main gearbox to the fuselage?

LIVE (Liquid Inertia Vibration Eliminator) mounts.

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What does the LIVE mount do?

Isolates the fuselage from 2/r main gearbox vibration.

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How does a LIVE mount work? (2 elements)

Vertical motion of the main gearbox causes pressurised fluid to flow between two chambers.
Stop mounts prevent excessive main gearbox movement relative to the airframe.

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What is the rotor head type?

Semi-rigid, underslung hub with a feathering axis.

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What part connects the blade grips to the yoke?

The Tension-Torsion strap.

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What is the purpose of the Tension-Torsion strap?

To transmit centrifugal loads from the blades to the hub, and to counteract aerodynamic forces.

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How is the Tension-Torsion strap constructed?

Stainless steel wire wrapped around two steel ends.

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What does the flapping restraint do?

Prevents excessive blade flapping at low rotor RPM.

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How does the flapping restraint work?

Counterweights move outwards under centrifugal force at high RPM and withdraw the flapping restraint stops.
At low RPM, springs move the counterweights back inwards.

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Which two components are connected to either end of the tail rotor driveshaft?

The freewheel unit and the tail rotor gearbox.

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How many tail rotor driveshaft segments are there?

Eight.

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From what material is the tail rotor driveshaft made of within, and forward of, the oil cooler assembly?

Steel.

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From what material is the tail rotor driveshaft constructed aft of the oil cooler assembly?

Aluminium alloy.

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What type of couplings connect the tail rotor driveshaft segments?

Thomas Coupling disc packs.

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How many Thomas Coupling disc packs are there in the tail rotor driveshaft?

Nine.

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What is the purpose of the flat spot on a Thomas Coupling disc pack?

To indicate metal grain direction and ensure correct composition of the pack.

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What is the purpose of a Thomas Coupling disc pack?

To allow for slight angular misalignment of the driveshaft segments.

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What is the construction of a Thomas Coupling disc pack?

A stack of stainless steel discs to which driveshaft segments are attached by points 90 degrees apart.

What is the purpose of the tail rotor gearbox?

To reduce speed and change direction of the drive by 90 degrees.

Where are the four chip detectors located in the transmission system?

Two in the main rotor gearbox.
One in the freewheel unit.
One in the tail rotor gearbox.

What does a yellow T/R CHIP caption indicate?

Metal chips detected in the tail rotor gearbox.

What does a yellow XMSN CHIP caption indicate?

Metal chips detected in the main gearbox lubricating oil by either of the two main gearbox chip detectors or the freewheel unit chip detector.

** What is the urgency of the need to land associated with any yellow CHIP caption?

Land as soon as POSSIBLE.

What is the urgency of the need to land associated with any yellow CD INOP caption?

Land as soon as practical.

What is indicated by a yellow DRIVE CD INOP caption?

One of the four transmission chip detectors has failed the CHIP TEST sequence.

What is the urgency of the need to land associated with a yellow DRIVE CD INOP caption?

Land as soon as practical.

What is the purpose of the delta-hinge on the tail rotor?

To reduce excessive flapping.

How does the delta-hinge on the tail rotor function?

- Flapping caused by lift dissymmetry between the advancing and retreating blades is translated by the angle of the hinge into an angle of attack difference between the blades. - This difference of angle of attack causes a lift differential which opposes the original dissymmetry, reducing its magnitude.

What are the weights for on the inboard trailing edge and the tips of the tail rotor blades?

Tail rotor balancing.

How many types of oil are permitted in the transmission and can they be mixed?

Two. They MAY NOT be mixed.

What is the urgency of the need to land associated with the Red XMSN TEMP caption?

Land as soon as practical.

What type of component is the functioning part of the Freewheel unit?

A Sprag-type clutch.

During walk-round, what would indicate that the main gearbox oil filter bypass had been activated?

The red pop-out indicator on the oil filter manifold - aft upper left of the main gearbox - will be extended.

What drives the oil cooler blower?

The tail rotor drive shaft.

What three functions do the hanger bearings provide for the tail rotor driveshaft?

- Support the driveshaft. - Allow the driveshaft to rotate. - Allow slight fore/aft movement of the driveshaft.

Where is the main gearbox oil sight-glass located?

Lower right side of the main gearbox (visible through a cut-out in the transmission fairing).

The transmission oil pump is driven by the same shaft that drives which other service?

The hydraulic pump.

How is the main rotor gearbox oil sight glass inspected?

Through a cutout on the right hand side transmission fairing

What indicates a transmission chip while the WOG is active?

The associated CHIP advisory will illuminate

Where is the main rotor gearbox oil filler?

Top right hand side of the main rotor gearbox

How many chip detectors could activate the Yellow XMSN CHIP caption?

Three - two in the MRGB, one in the freewheel unit.

Where is the main transmission oil filter housing?

Aft upper left side of the transmission

What is the result of the main transmission oil filter bypass opening?

Unfiltered oil reaching the main rotor gearbox

What does the thermostatic valve do within the transmission oil system?

Bypasses the oil cooler depending on oil temperature

What would happen if the oil cooler were to become blocked?

High differential pressure across the thermostatic valve would cause it to open, allowing hot oil to the gearbox

What is the urgency of the need to land associated with the red XMSN TEMP caption?

Land as soon as practical.

**What are the Immediate Actions for a Red XMSN OIL PRESS caption?

- Reduce power - Verify oil pressure - Land ASAP

How is the Tension-Torsion strap constructed?

Stainless steel wire wrapped around two steel ends.

What are the weights in the blade bolt shanks for?

Static and dynamic balance of the hub and blade assembly

Why are the yolk journals pre-coned?

To relieve stresses on the hub assembly