TRANSMISSION SYS

Question 1

What is the primary function of the transmission system?

Answer 1

to take the combined power from both engines, reduce the rpm, and transfer it to the main and tail rotors

Question 2

What is the secondary function of the transmission system?

Answer 2

to provide a drive for electrical and hydraulic power generation

Question 3

The main gear box has what type of design?

Answer 3

a modular design with a 3 degree forward tilt

Question 4

What type of lubrication system does the MGB have?

Answer 4

the MGB is pressure lubricated and contains a wet sump lubrication system that provides cooled, filtered oil to all main transmission bearings and gears. Oil pressure is provided by two pumps in parallel so that if one fails, pressure will still be provided but will be lower.

Question 5

What is the capacity of the wet sump in the MGB? How many pumps does it have?

Answer 5

7.5 gallon capacity, two pumps

Question 6

When will the chip detector/temperature sensor in the wet sump trip an [MAIN XMSN OIL HOT] advisory?

Answer 6

if temperature > 105C

Question 7

How is the xmsn oil cooled?

Answer 7

via an air/oil cooler that uses a blower driven by the rotor drive shaft

Question 8

What advisories/cautions will the pressure sensor in the MGB illuminate and when?

Answer 8

[MAIN XMSN PRESS HI] caution = psi > 130
[MAIN XMSN PRESS HI] advisory = 65-130psi on VIDS
[MAIN XMSN PRESS LO] advisory = when < or equal to 30psi with Nr > 25%

Question 9

When will the [MAIN XMSN OIL HOT] caution illuminate? Where is the sensor located?

Answer 9

caution illuminates when temperature > 117C

located in the MGB at the air/oil cooler input to the MGB where the oil should be the coolest.

Question 10

What do the input modules provide? What do they contain?

Answer 10

The input modules provide the first stage of gear reduction and house the freewheeling unit.

Question 11

What is the purpose of the diaphragm coupling?

Answer 11

allows for slight angular or axial misalignment of the output shaft in the input module during normal ops.

if a whining noise occurs during rotor engagement, this could be indicative of a diaphragm coupling failure and the aircraft must be shutdown immediately.

Question 12

What is the purpose of the accessory modules?

Answer 12

to provide mounting and drive for the AC generators and hydraulic pumps

Question 13

What sensors are located on the #1 and #2 accessory modules?

Answer 13

Right accessory module — Nr sensor for the vertical instruments
Left accessory module — Nr sensor for TDI colocated with the main transmission low oil px sensor

Question 14

Where is the [MAIN XMSN PRESS LO] caution sensor located and when will it illuminate?

Answer 14

in the #1 accessory module, illuminates if pressure < 14psi

Question 15

How many chip detectors are there for the main transmission system?

Answer 15

5 chip detectors — 2 input, 2 accessory, 1 main

Question 16

How are the IGB and TBG lubricated?

Answer 16

splash lubricated with a 2.75 pint capacity each

Question 17

When are the [IGB OIL HOT] or [TGB OIL HOT] cautions illuminated?

Answer 17

when temperature > 140C

Question 18

Main transmission malfunctions can be grouped into two categories, what are they?

Answer 18

chip or lubrication malfunctions

Question 19

What is the difference between a steady, low xmsn oil pressure vs. a continually decreasing pressure?

Answer 19

a steady low pressure may indicate a single pump failure in the wet sump

a decreasing pressure may indicate a leak

Question 20

What are the possible indications of a main transmission imminent failure?

Answer 20

yaw attitude excursions with no control input, increase in power required for a fixed collective setting, failure of a main generator or hydraulic pump, increased noise, vibrations, or abnormal fumes in the cabin.

Question 21

How many sections is the tail drive shaft and how is it suspended?

Answer 21

The tail drive shaft has 6 sections, is ballistically tolerant, and is suspended at 4 points by viscous-damped bearings.

Question 22

What feature do the IGB, TGB, and main transmission chip detectors provide?

Answer 22

Burn off feature — eliminates false warnings by fuzz and minute particles. This feature is deactivated when oil > 140C because that is the oil flashpoint

Question 23

How long is the CHIP IBIT?

Answer 23

2 minutes of which the first 40 seconds WCAs and the MASTER CAUTION lights will not respond

Question 24

How long needs to be waited after shutdown before checking the transmission oil level?

Answer 24

30 minutes