Engine pull!
Today was engine pull day. It was the first one I've ever done completely on my own, and I did okay! Didn't forget anything, didn't drop the engine (I did have another mechanic help with the hoist- that can be done by one person, but it's sooooo much easier with two). It took me about 4 hours, which is respectable, though if I had to, I could probably do it faster. Still, not bad considering I haven't done one in almost a year, and considering I'm still not that fast at maintenance in general. Always room for improvement!
Removing the engine from an AStar requires (obviously) disconnecting all the lines going to it- the electrical harnesses, fuel supply and drain lines, oil supply and return lines, the P2 air lines (P2 is shorthand for air bled off the compressor to use for something else- in the case of the one that goes to the airframe, it takes air from the second stage of the compressor (hence, P2) and ducts it into the ventilation system where it mixes with outside air for demisting and defrosting the inside of the cabin), and the heater pads that are used to preheat the gearboxes (keeps the oil from turning to sludge- the same way you preheat a car or truck engine in a cold climate). It also requires removing the starter (for access to the front support of the engine), the inlet (same reason), and disconnecting the front and back coupling shafts.
The front shaft is the first stage in the main rotor transmission system- it feeds the rotation from the engine into the main gearbox, where the rpm is reduced and the direction of rotation is changed. The power shaft in the engine is horizontal, and so is the coupling shaft- they spin the same way a stand-mounted fan would. However, the mast that supports the main rotor head is, of course, vertical- the blades spin like a ceiling fan. The main gearbox makes that change in spin direction happen.
The rear coupling shaft comes out of the engine and hooks to the long driveshaft (the actual coupling shaft is only about 2 feet long, whereas the long shaft is more like 12 feet), which in turn drives the tail rotor gearbox..
I like engine work. It's pretty amazing to me that that little engine (it only weighs about 200 lbs, and isn't much longer than a clothes basket) makes enough power to lift not only the helicopter, but the helicopter's payload capacity as well! Quite a tribute to engineering and science!
Removing the engine from an AStar requires (obviously) disconnecting all the lines going to it- the electrical harnesses, fuel supply and drain lines, oil supply and return lines, the P2 air lines (P2 is shorthand for air bled off the compressor to use for something else- in the case of the one that goes to the airframe, it takes air from the second stage of the compressor (hence, P2) and ducts it into the ventilation system where it mixes with outside air for demisting and defrosting the inside of the cabin), and the heater pads that are used to preheat the gearboxes (keeps the oil from turning to sludge- the same way you preheat a car or truck engine in a cold climate). It also requires removing the starter (for access to the front support of the engine), the inlet (same reason), and disconnecting the front and back coupling shafts.
The front shaft is the first stage in the main rotor transmission system- it feeds the rotation from the engine into the main gearbox, where the rpm is reduced and the direction of rotation is changed. The power shaft in the engine is horizontal, and so is the coupling shaft- they spin the same way a stand-mounted fan would. However, the mast that supports the main rotor head is, of course, vertical- the blades spin like a ceiling fan. The main gearbox makes that change in spin direction happen.
The rear coupling shaft comes out of the engine and hooks to the long driveshaft (the actual coupling shaft is only about 2 feet long, whereas the long shaft is more like 12 feet), which in turn drives the tail rotor gearbox..
I like engine work. It's pretty amazing to me that that little engine (it only weighs about 200 lbs, and isn't much longer than a clothes basket) makes enough power to lift not only the helicopter, but the helicopter's payload capacity as well! Quite a tribute to engineering and science!