t56 Flashcards
What is the purpose of the torque meter and tie struts
transmit and measure torque from power section to reduction gearbox
provide alignment and rigidity
Major components of the torque meter and tie struts
housing torque shaft reference shat torquemeter pickup assy tie struts
what is the toque meter housing and tie struts made of
steel
what does the torquemeter mid bearing (roller) do
prevents whip under high torque loadings
what does the torque shaft connect to
safety coupling on the input quill on the reduction gear box, and the compressor extension shaft
how many teeth does the torque meter have?
and this generates a signal for what gauge?
40 teeth, generate HP for the flight deck gauge
where are the sleeve bearings and what do they do
at the centre and forward end, support the reference shaft and allow the torque shaft to twist under load without affecting the R.S
why must you monitor the horse power gauge during high power (and under certain conditions)
and again in low power?
it may cause the wing and engine mount structure to become over stressed, as a result of too much power.
low power- insufficient power for safe AC operation
calibration of the torquemeter system and horsepower gauge is required on what occasions
horse power gauge change engine change pickup change after a periodic servicing prior to doing an engine performance run
what is torquemeter runout test
and when will this be performed
what device is used with a T.R test
when the gap between the teeth on the torque shaft and torquemeter pickup varies due to a failing pinion bearing or safety coupling
performed after a heavy landing or if engine vibrations are suspected/evident
oscilloscope
purpose of the reduction gearbox
reduce high engine rpm to a usable propeller rpm and to drive assy
what are the 2 stages of reduction within the gearbox
1st stage- spur type reduction. 3.125:1
2nd stage- planetary reduction. 4.333:1
what is the overall reduction
13.54:1
power section rpm 13820: 1021 prop shaft rpm
what are the main structural parts of the reduction gb
what is it made of
magnesium alloy front case main diaphragm rear case rear case inner diaphragm
what does the front case of the reduction gearbox house
thrust sensitive system operating mechanism
negative torque system operating mechanism
nose scavenge pump
planetary system ring gear
what is mounted externally to the front case of the reduction gearbox
12 o clock position: upper ESU mount
3 o clock position: TSS switch
what does the main diaphragm of the RGB housing support
rear end of the propeller shaft
forward end of the input drive pinion
main drive gear
planetary sun gear
what does the rear case of the RGB support (internally)
and externally
internally: rear end of the input pinion rear ends for the assy drive train gears shafts rear case inner diaphragm main scavenge pump
externally:
ESU (3,6,9 o clock positions)
external mounting pads for the gearbox driven assys
purpose of the rear case inner diaphragm
support the forward ends of the assy drive train gear mounts
components/ assys mounted to the rear face of the RGB rear case
generator engine driven compressor pressure oil pump and filter tacho generator starter
what are the safety devices located internally on the RGB
propeller brake
NTS
safety coupling
TSS
what is the purpose of the Prop brake
prevent prop rotation when feathered in flight -to reduce drag - to prevent secondary damage reduce engine rundown time prevent windmilling on the ground
what is the purpose of the NTS
generated whenever the propeller attempts to drive the engine. mechanical mechanism that senses negative torque and transmits a mechanical signal to the prop which coarsens the blade angle until the NT ceases
when does the NTS operation occur on the inboard/outboard engines.
why are they different
inboard: -100-500 HP
outboard: -150-500 HP
due to the EDCs being fitted to inboard engines. Negative torque effort used to drive the EDCs is not sensed by the torquemeter sensor (49HP to drive EDC)
in an extreme setting what safety devices may be used in a negative torque situation
NTS
Safety coupling between RGB and power section drive
when will negative torque occur
sudden loss of power
turbulence/ wind gusts/ rain/ thunderstorms
low power settings on decent
momentary NT will occur
1) on downshift from normal RPM to low speed and
2)on engine shutdown
purpose of the safety coupling
prevent excessive propeller drag should the propeller begin to drive the engine (prop extracting energy from the slipstream)
it will automatically decouple the reduction GB from the power section whenever the NTS is unable to control the NT, & the NT exceeds -1700HP. the device will recouple itself once the NT decrease below -1700HP
how will you know if the safety coupling has disengaged
HP gauge will be reading -1000HP. HP gauge- negative indication.
May feel the asymmeteric power effect on the AC
what does the TSS do
provide an automatic means to shut down the engine and feather the prop in the event of engine power loss at high power setting. mechanically initiated and electrically activated
what conditions must be met for the TSS to mechanically initiate
autofeather system armed
power lever above 60 deg
lessthan 500lb of propeller thrust
when would you use TSS (normal operation)
usually used only for take off
how many thermocouples are fitted to the engine
18
why is it important that the thermocouples are indicating correctly
false indications of engine performance
significantly reduce life of turbine components
what is the H dimmension
the linear distance between the junctions embedded in the insulating material
thermocouples with a high h dimension will read …
under read the TIT
cause the engine fuel system to supply more fuel than actually desired
what is sulphidation
and what does it look like
accelerated oxidation of metals in the presence of sulphate ions.
“hot corrosion”
mild-whitish deposits.
serious- blistering, exfoliation
how can you minimize sulfidation
reducing low altitude flying over the sea
avoiding areas of high air pollution
fly with reduced TIT
what oil is used in the t56-a-14
mobil jet oil 2 (synthetic oil)
oil system operating limits
power section:
RGB:
normal oil temperature:
PS: 50-60 psi
RGB:150-250 psi
normal oil temp: 60-90 deg
what is the purpose of the power section pressure filter check valve
prevent the contents of the oil tank draining down into the engine when it is stationary
what is the pressure adjusting valve in the oil system
in the event of an oil passage or jet becoming blocked, the oil pressure will rise indicating a blockage has occurred.
what types of RGB oil pumps are there
main scavenge pump- driven from the assy gear train
nose scavenge: driven from the prop shaft
pressure pump- gear type
oil sump components
shut off valve
electrically actuated
drain rooster/ cock
temperature bulb
this is in the position of the “coldest” oil in the QEC
temperature switch
located at the outlet. illuminates when the switch reaches 100*C
oil scavenge system components
external scavenge filter fuel heater strainer oil cooler EDC oil cooler oil cooler augmentation piccolo tubes oil cooler flap
sources of bleed air
engine
auxiliary power unit
ground air supply cart
systems which use bleed air
compressor bleed valve engine air inlet housing and intake scoop anti icing engine starting oil cooler augmenting wing anti icing bomb bay heating AMP
purpose of the bleed air check valves
prevent reverse flow of bleed air, from other sources, passing into the diffuser when the engine is stationary and/or during engine starting
what valve supplies bleed air to, and modulates the control of, the engine starter
engine start control valve
engine bleed air systems which are not supplied from the QEC bleed air manifold or AC bleed air manifold are
AIH anti icing system
air inlet duct anti icing system
engine compressor bleed valves operation
these systems are connected directly to their respective engine diffuser
what is a compressor stall
the higher pressure air in the combustion section flows forward through the compressor and exists out the engine intake. the pressure in the combustion section is quickly dissipated, the compressor again begins to pump air normally through the engine and the cycle repeats
what overcomes compressor stall (component)
when would you use them
8x bleed air valves around the 5th and 10th stage compressor are dumped.
these are open from 0-94%
during starting, acceleration and slow speed running
what component is responsible for porting 14th stage bleed air onto the bleed valves (opening and closing them at 94%)
speed sensing valve
what positions are the igniter plugs location at
2 and 5
when carrying out any maintenance on the ignition system, the fuel shut off valve must be pulled. why
the fuel and ignition control cb will not isolate the syem
major components of the starting system
engine starter (airesearch air turbine type)
start control valve (mushroom tophat)
geneva loc
Engine identification of the t56
T-turboprop
56- designation of the engine
A-manufacturers name
14- model no of the designation
ESHP- 100% RPM- Reduction ratio- Prop speed- TIT- Max start-
4910 13,820 13.54:1 1020.6 1077(1083) 830-850
Oil publications
Fols
Flight manual
F700
Ss&rps
Normal rpm
Low
Takeoff
Flight idle
96.3-99.1
71.0-73.8
99-101
94.5-98.4
Basic engine is made up of
Power section
Torque meter and tie struts
Reduction gearbox
Parts that make up the power section
Compressor
Combustion
Turbine
Assy gearbox ???
Things attached to the outer surface of the AIH
12-Engine breather 3-Anti ice valve 6-Assy gb 7- no 2-4 oil outlet 8- fcu probe 9- anti ice valve 10- no 1 bearing labyrinth seal vent
6 o clock strut of the AIH has additional passages for
Assy gb driveshaft
Pressure oil to the inner casing
Scavenge oil from the inner casing to the assy gb
Venting air to/from assy gb
Where is the diffuser located
Purpose of the diffuser
Between compressor section and outer combustion case. Forward of the engine firewall
- Directs compressor discharge air into the combustion section
- Provides mounting lad for 6 fuel nozzles
- Mounting point for the rear engine mounts
- Bleed air tap off for the AC pneumatic systems
Major components of the combustion section
Outer and inner combustion casing Inner combustion casing liner 6 combustion cans Turbine coupling shaft Lighthouse cavity
What things support/ hold up the combustion cans
Liner supports Fuel nozzles 3 thermocouples 1st stage nozzle guide babes Cross over ducts(where the flame is propagated from)
What do tangential struts do
Compensate for the heat expansion to ensure inner shell stays concentric with the outer shell to prevent turbine rub
How is the assy gb driven
Compressor extension shaft down the 6 o clock strut of the AIH
What components are driven off the assy gb
Fcu External scavenge pump Fuel pump cluster Speed sense valve Speed sense control Main pressure and scavenge oil pumps
Chip detector
External vent
Power section pressure oil filter
Purpose of the propeller brake
Prevent prop rotation when feathered Reduce drag Prevent secondary damage Reduce engine rundown time Prevent windmilling
What are the 3 operating positions of the prop brake
Released:>21%
Engine started is operating.
Applied: <21%
Locked: whenever prop is turned in locked position
Planetary and spur gear reduction ratio in the rgb
Spur- 3.125:1
Reduction-4.333:1
How does the prop brake “hold”
As engine rpm increases, rgb oil pressure rises and at approx 21% the oil pressure is sufficient in the cylinder within the outer cone to hold the brake released even when the starter is disengaged
What is the priority for engine auto feather when tss is used and why
4,1,3,2
Gives priority to the outboard engines as they have an asymmetric effect on AC
Prop rotation
Turbine rotation
Compressor rotation
Combustion can identification
Clockwise
Anti
Anti
1 at top, clockwise
Basic engine-
ESU-
QEC-
Basic:
Power section
Torque meter and tie struts
Rgb
ESU: Cowlings and support structure Intake ducting Structural mounting (engine) Structural braces (airframe)
QEC:
Basic engine
ESU
Power section made up of
Compressor
Combustion
Turbine
Assy gb
Purpose of the air inlet guide vanes assy
Reduce fod
Direct air onto the first stage of the compressor at the correct angle
Where does the no 1 labyrinth seal get it’s pressurised air from
6th stage compressor air
How does air escape after it has leaked past the no 1 bearing labyrinth seal
Forward face of the compressor rotor and joins the air flow onto the compressor
Through the engine breather
Scavenged with the oil returning to the assy gb (6 o clock strut)
When will you do a torque meter runout test
Suspect engine vibrations
Heavy landing
oil is ported into the AIH 6 o clock strut and into the AIH inner casing to lubricate what
No 1 bearing
Compressor extension shaft bearing
Side gear and bearings
Torque meter mid bearing and mid sleeve bearing
Port oil down the lower lh strut of the AIH
major components in the engine starting system
engine starter
start control valve (mushroom tophat)
generva loc(fcu fuel shut off valve)
engine starting air is supplied from
another engine
apu
ground cart
why do we have oil cooler augmentation tubes
when props are positioned between ground idle and max reverse, the blades are at negative angles. no air is directed in the oil cooler intake duct.
under these conditions, oil temp can exceed allowable temp (100%)
what are the 2 anti icing systems that utilize the 14th stage bleed air
AIA antiicing
air inlet duct anti icing
what areas and components of the AIH are heated
leading edge of the 8 radial struts in the AIH
each vane of the compressor inlet guide vane assy
fcu temp sensing probe shroud
upper half of the torquemeter shroud
what will happen when you use the anti icing system
TIT rise of approx 20*C
200-300HP drop
2 separate mechanical control system for each engine
power lever
e handle
when the E handle is pulled… what happens (mechanically)
mechanically operated systems: fuel shut off at FCU fuel shut off at wing beam generator blast duct cooling air shut off prop feathers
when the E handle is pulled… what happens (electronically)
fuel shut off at fcu oil shut off at oil tank sump outlet dumps edc pressure overboard and closes edc firewall shut off valve bleed air shut off at engine firewall prop feathers
what is the coordinator
coordinates power level and e handle operation to the fcu and prop
provide a power lever position/TIT reference signal above 66* coordinator position
where are the fire zones and the temperature
zone 1:QEC, 600*
zone 2: forward of the firewall, 400*
3: wheel well, 400
fire extinguishing bottles contain ___ and are pressurised to ____
10.5lbs halon (BCF)
nitrogen, 600 psi
high rate discharge. discharges within 0.4s
how many fire bottles are allocated to an engine, and how do you fire them
2 bottles per wing.
each engine is allocated a bottle, however a second bottle for the adjacent engine, can be transfered
can you transfer fire bottles between engines
yes, on the same wing only
flight deck fire indications
steady red light illumination surrounding e handle
audible horn in flight deck
audible horn in tac station(only if ac if on ground)
areas of electrical power supply components
generators
main load centre
forward load centre
generators are only available if
generator switch is on
engine is at normal rpm
apu is over 95%
how do you convert _Ac to _dc
tru
115VAC to 28VDC
are you a tru ac/dc fan
how do you convert dc power to ac
inverter
Reduction gearbox oil pressure is the result of
Oil viscosity
Volume flow
Restriction to flow
Oil tank
Usable:
Unusable
Air foaming space
- 65 us gallons
- 4 US gallons
- 7 us gallons
Sources of venting/breathing air into the engine breather unit
1) 12 o clock strut of AIH
Reduction gb through torque meter
Assy gearbox through 6 o clock strut
2) External flexible tubes
1 bearing labyrinth seal
Assy gb
Oil tank pressurising valve
Why will the flight deck show a increase of TIT if the augmentation is satisfactory
(Oil cooling system)
Fuel system is in temp limiting, there is less compressor air for the same scheduled fuel
What are the bleed air passages/areas for the AIH
8Leading edges of AIH
Inlet guide vanes
Torque meter shroud via external hose
fcu temp probe shroud
2 anti icing engine systems
AIH
Inlet duct
Throttle positions Max reverse Ground idle Ground start Flight idle Crossover Take off
In degrees 0 9 15 34 66 90
Throttle ranges Ground range Flight range Temp limiting Temp control
In degrees 0-34 34-90 0-66 66-90
Mechanically operated systems when e handle is pulled
Fuel shut off at fcu
Fuel shut off at wing beam
Generator blast duct cooling air shut off
Prop feather valve
Electrically operated systems when e handle is pulled
Fuel shut off at fcu Oil shut off at tank sump outlet Demos edc pressure overboard Bleed air shut off at eng firewall Prop feather
Mechanical inputs and outputs to the coordinator
And electrical output
Input
Power lever
E Handle
Output
Prop control
Fcu fuel scheduling
Fcu shut off
Electrical outputs
66degree microswitch
1000 ohm potentiometer
