Engines

Question 1

When is the torque check on the high speed shaft due for the No. 1 Engine on Aircraft 09265 if maintenance was completed at 2134.5?

Answer 1

2147.5 Aircraft Hours

d.IF TORQUE ON ANY BOLT IS BELOW 130 INCH-POUNDS, RETORQUE TO 130 - 140 INCH-POUNDS. Repeat torque check after each 3 to 13 flight hours until torque stabilizes. e.If torque does not stabilize after third consecutive torque check, replace engine output shaft assembly connecting hardware and flange coupling. Perform engine output shaft balance testing (WP 0354).

Question 2

Under the modular maintenance concept the engine is divided into what modules?

Answer 2

Under the modular maintenance concept, the turboshaftengineis divided into fourmodules:

● Accessory Section Module (Accessory Gearbox)
● Cold Section Module (Compressor Section)
● Hot Section Module (Combustion Section)
● Power Turbine Module (Power Turbine)

Question 3

How are DECU/EDECU fault codes cleared after they have been corrected?

Answer 3

DECU, PNs 5086T83P03/4082T99G09 will display a 95% (±3%) fault code in the cockpit if test A and test B buttons are pressed repeatedly when the DECU is powered up by the APU generator or ground power cart and the main engines are off-line. This DECU response will not affect flight safety, nor will it affect the function of the DECU. The fault codes can be cleared by running the engine at 100% Np speed. DECU, PNs 5086T83P05/ 4082T99G12 will display a 95% (±3%) fault code in the cockpit if test A and test B buttons are pressed repeatedly when the DECU is powered up by the APU generator or ground power cart and the main engines are off-line. This DECU response will not affect flight safety, nor will it affect the function of the DECU. The fault codes can be cleared by running the engine at 100% Np speed. DECU, PNs 6068T56P06/5078T29G05 will display a 95% (±3%) fault code if the OVSP TEST switches are pressed repeatedly to clear DECU fault codes when the engine is not operating. This fault will be cleared during the next start after the starter has dropped off. This DECU response will not affect flight safety, nor will it affect the function of the DECU. DECU, PNs 6068T56P07/5078T29G06 will display a 95% (±3%) fault code if the OVSP TEST switches are pressed repeatedly to clear DECU fault codes when the engine is not operating. This fault will be cleared during the next start after the starter has dropped off. This DECU response will not affect flight safety, nor will it affect the function of the DECU. The fault codes can be suppressed by depressing either one of the engine overspeed test buttons. The fault codes can also be recalled by again depressing either one of the overspeed test buttons. Any fault code that appeared on the engine torque indicator should be recorded on form 2408-13. Refer to WP 0008 for the appropriate troubleshooting procedure. If the problem has been corrected, the fault code will be cleared. To verify the fixes following corrective action, it is required to operate the engine at flight idle. If the problem has not been corrected, the fault code will again flash on the engine torque indicator when the above conditions are met.

Question 4

What events are cause for engine sudden stoppage removal and inspection?

Answer 4

● A high deceleration rotor incident resulting in removal of the main transmission, input modules, and/or nose gearboxes.

● The event caused damage to engine mounts or attaching hardware.

● The event caused unusual noise or rubs.

Question 5

What checks must be performed an engine is re-installed? WP0698

Answer 5

40.Check engine oil level and service as required (WP 0220).
42.Perform operational cowlingheck of IVHMS (WP 0131).
43.Perform engine output shaft balance testing (WP 0354).
44.Perform the following: a.Run up engine for at least 10 minutes. Let engine cool down for one hour minimum. b.Perform a torque check of the deswirl duct loop clamp nuts. TORQUE SHOULD BE 35 - 40 INCH-POUNDS. If torque is below limit, repeat Step 39a. Torque stripes to be used only on loop clamp, 70300-30800-102.
46.Perform engine checkout procedure as part of maintenance operation check/maintenance test flight (TM 1-2840-248-23&P).
48.Perform a maintenance test flight (TM 1-1520-280-MTF).

Question 6

What are the four modules of the turbo shaft engine?

Answer 6

Cold section module, Hot section module, Power turbine module, Accessory section module.

Question 7

What are the oil sumps contained within the engine, and what bearings do they contain?

Answer 7

A sump – bearings 1, 2, 3 B sump – bearing 4 C sump – bearings 5, 6

Question 8

What does the T701D incorporate on the internal engine components to improve the heat tolerance of those components?

Answer 8

Thermal Barrier Coating (TBC)

Question 9

What component provides torque matching and how does it accomplish that?

Answer 9

DEC – by increasing the NP reference on the low torque engine

Question 10

What connects the compressor section to the accessory gearbox?

Answer 10

PTO bevel gear through the radial drive shaft assembly.

Question 11

What do the inlet swirl vanes do?

Answer 11

Swirls the air and throws heavy particles out to the particle separator blower.

Question 12

Locate the two borescope port locations on the left side of the engine?

Answer 12

Compressor casing, 8:00 o’clock position (compressor aft) Ignitor port, 8:00 o’clock position (combustion section)

Question 13

What is the max vibe allowed for the high speed shaft? At what vibe level must the shaft be replaced?

Answer 13

.5 IPS
2.0 IPS

Question 14

If you have 3 stuck balance screws in the H/S shaft how many more balance screws can be installed?

Answer 14

3

Question 15

After reconnecting the high speed shaft, what is the maximum time the aircraft can fly before performing a high speed shaft re-torque?

Answer 15

13 Hours (3-13hr TQ Check)

Question 16

What component provides load sharing capability?

Answer 16

DEC/EDECU

Question 17

What is the purpose of the oil system scavenge screens?

Answer 17

They collect particles before they enter the scavenge sections of the lube and scavenge pump. These screens prevent damage to the pump. The six screens are individually labeled to show which sump the particles came from.

Question 18

List the oil system sumps and the bearings located within each sump?

Answer 18

(a)A-sump - No. 1, 2, and 3 bearings.
(b)B-sump - No. 4 bearing.
(c)C-sump - No. 5 and 6 bearings:

Question 19

What checks must be performed when an engine is re-installed?

Answer 19

40.Check engine oil level and service as required (WP 0220).
42.Perform operational cowlingheck of IVHMS (WP 0131).
43.Perform engine output shaft balance testing (WP 0354).
44.Perform the following: a.Run up engine for at least 10 minutes. Let engine cool down for one hour minimum. b.Perform a torque check of the deswirl duct loop clamp nuts. TORQUE SHOULD BE 35 - 40 INCH-POUNDS. If torque is below limit, repeat Step 39a. Torque stripes to be used only on loop clamp, 70300-30800-102.
46.Perform engine checkout procedure as part of maintenance operation check/maintenance test flight (TM 1-2840-248-23&P).
48.Perform a maintenance test flight (TM 1-1520-280-MTF).

Question 20

What is the purpose of the Anti-Icing Starting Bleed Valve?

Answer 20

Vacco Anti-Icing Bleed and Start Valve Air

The anti-icing system prevents ice from forming in the flow path of the engine inlet. The valve also bleeds air from the compressor during engine starting. This reduces back pressure on the axial compressor at lower speeds and prevents compressor stall.

Question 21

What checks are required for a DECU/EDECU replacement? What order would you conduct them in?

Answer 21

WP 0116, Engine Starting Procedures
WP 0120, Determining (Aircraft) TGT Limiter Setting
WP 0121, Determining (Aircraft) TGT Limiter Setting/Contingency Power Check
WP 0123, Overspeed Check
WP 0124, Overspeed Check
WP 0125, (T701C T701D) Check TGT Bias Indications
WP 0131, Idle Speed Leakage Check
WP 0133, Np Governing Check
WP 0134, Torque Matching Check

Question 22

The power turbine section furnishes the power required to turn the main rotors.

Answer 22

True

Question 23

Which accessory gear/axis, if failed, would result in the loss of HMU functions?

Answer 23

E Axis.

Question 24

What gear/axis drives the accessory gear box during the initial engine start procedures? After engine start is completed?

Answer 24

B axis. A axis.

Question 25

What component protects the oil system during cold starts by discharging oil to the gear box?

Answer 25

Cold Oil Relief Valve.

Question 26

How many Engine stations are there?

Answer 26

6

Question 27

Station 1

Answer 27

Located at the leading edge of the swirl frame inlet.

Question 28

Station 2

Answer 28

Located at the compressor Frame Inlet and is the location for the inlet air temperature (T2) used for fuel metering system.

Question 29

Station 3

Answer 29

Located at the trailing edge of compressor's sixth stage and provided the pressure tap for compressor discharge air (P3 Air).

Question 30

Station 4

Answer 30

Located at the gas generator turbine's 1st stage nozzle leading edge.

Question 31

Station 4.5

Answer 31

Located at the gas generator's 2nd stage rotor discharge and provides the mounting point for the turbine gas temperature harness and probes.

Question 32

Station 5

Answer 32

Located at the exhaust's frames leading edge.

Question 33

Engine Overview

Answer 33

• The gas turbine engine is a system of components that use air as a working fluid. • It extracts energy from the working fluid to drive the aircraft's rotor system and sustain engine operation. • The T700 engine utilizes an air/fuel mixture that is ignited to produce a continuous burn which creates exhaust gases. The exhaust drives a “fan section” which in turn drives the rotor system. • This system works on an intake, compression, combustion/expansion, and exhaust principle (Suck, Squeeze, Bang, and Blow). • The T701D performs the intake, compression, combustion/expansion, and exhaust function through the use of four basic sections. • Cold Section (Intake and compression) • Hot Section (Combustion/Expansion) • Power Turbine Section (Exhaust) • Accessory Gear Box Section (Subsystems) • Each component functions together generating the work required to sustain the engine while providing work in the form of shaft horsepower to the main rotor system.

Question 34

Intake (suck) Overview

Answer 34

• The front or inlet duct is almost entirely open to permit outside air to enter the front of the engine. • The compressor initially turned by the starter draws outside air into engine. • After engine start, the combustion processes turns the compressor continuously drawing in air.

Question 35

Compression (squeeze) Overview

Answer 35

• Its primary function is to supply enough air to satisfy the requirements of the combustion burners. The compressor must increase the pressure of the mass of air received from the air inlet duct and then discharge it to the burners in the required quantity and pressure. Pressure is increased by increasing air velocity through spinning rotors and then slowing air down through stationary stator vanes (Bernoulli’s Theorem). • A secondary function of the compressor is to supply bleed air for various purposes in the engine and aircraft. The bleed air is taken nom any of the various pressure stages of the compressor. The exact location of the bleed port depends on the pressure or temperature required for a particular job.

Question 36

Combustion (bang) Overview

Answer 36

• The combustion section contains the combustion chambers, igniter plugs, and fuel nozzle or fuel injectors. • It is designed to burn a fuel-air mixture and to deliver combusted gases to the turbine at a temperature not exceeding the allowable limit at the turbine inlet. • However, the fuel-air mixture has a ratio of l5 parts air to l part fuel by weight. • Approximately 25 percent of this air (known as primary air) is used to attain the desired fuel-air ratio (combustion). • The remaining 75 percent of air (known as secondary air) is used to form an air blanket around the burning gases and to dilute the temperature, which may reach as high as 3500ºF, by approximately one-half. This ensures that the turbine section will not be destroyed by excessive heat.

Question 37

Exhaust (blow) Overview

Answer 37

• The stator vanes, called nozzles, decrease the volume, increasing the velocity across the rotors extracting the necessary energy and converting it into shaft horsepower (Law of Conservation of Energy). • Up to 75% of the energy extracted is required to sustain the engine. • The remaining energy is extracted by the power turbine and drives the main rotor system. • This energy provides the propelling force to the airframe. • The engine is designed such that the gas generating turbine speed (Ng) varies due to load demand changes or varying aerodynamic conditions and maintains a constant Power Turbine (NP) speed directly proportional to the airframe Rotor Speed (NR).

Question 38

A sump

Answer 38

The No. 1 and No. 2 bearings support the output shaft. The No. 3 bearing is located on the forward end of the compressor and, support the gas generator rotor.

Question 39

B sump

Answer 39

No. 4 bearing, located between the compressor and turbine, support the gas generator rotor.

Question 40

C sump

Answer 40

The No. 5 and No. 6 bearings provide support for the power turbine rotor.

Question 41

DEC unit provides

Answer 41

Np governing, TGT limiting, Np overspeed protection, and load-sharing between the engines.

Question 42

TGT Limiting

Answer 42

• Dual engine limiting value: 879 ± 9°C. • Contingency power limiting value: 903 ± 10°C. • Automatic contingency power is provided by the DEC by resetting the TGT limiting to a higher value. • When the other engine is inoperative (engine failure or torque split). • When torque on other engine is below 50%. • Provides more power for single engine operation (approximately 5%). • The DEC commands the HMU to limit fuel flow to the engine when TGT reaches the limiting value. • TGT limiting does not prevent over-temp during compressor stalls, engine starts, or when the engine power control lever is in LOCKOUT. • When maximum power is demanded, transient increases above the limiting values can be expected to occur.

Question 43

Three additional factors that will place the EDECU into contingency power and set the TGT limiter to 903 +/- 10.

Answer 43

• NP drops below 96%. • Greater than 3% droop between reference power turbine speed (NP) and actual NP reference set point. • Greater than 5% per second NP droop rate exist and NP less than or equal to NP reference set point.