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)