# Just another night at work...



## nuuumannn (Oct 9, 2015)

Hi Guys,

While some of you Kool Kats were taking terrific pics of old warplanes at airshows and museums, the rest of us have been plodding on as usual. Tonight, three of us at work removed an engine from one of our aeroplanes and were messing about with our phone cameras after we'd finished the job. These are a few of the pics I took. Excuse the quality; the lighting in the hangar isn't great and these are taken with a phone, not a camera.

Taken from the stand after the engine's been removed. An engine change takes a couple of shifts, usually three guys on each shift. It'll take three guys three to four hours to disconnect everything, then remove the engine and do final prep for installation of the new engine. We usually do this at night and the morning shift come in a few hours later and begin reinstallation, which takes around the same time, although there is the engine run, which can take an hour, or more if something is wrong:







This is the rig we fit to the cowl in order to lower the engine; there's carpet placed over the cowl to protect it from the chains. Note that the hydraulic pump is poking up above the top of the cowl. That stays with the cowl and is refitted to the reduction gear box (RGB) after the engine's been installed. The table below has the bits we removed from the engine before dropping it from the aircraft, including AC generator, pre-cooler, engine mounts and assorted tubing and things:






The engines after removal; the removed at front and the new engine just forward of the cowl. The engines are overhauled overseas, but we have an engine shop for installing ancilliary equipment:






P WC PW 123 free turbine engine. For all you engine nerds, two centrifugal compressors driven by axial turbines, with a third power turbine driving the propeller through the RGB. Diffuser pipes between the LP and HP compressors can be seen ahead of the firewall. The black square is the Electronic Engine Control Unit (ECU), or FADEC box; basically the brain of the engine, which controls fuel flow via the Mechanical Fuel Control (MFC) directly above it. The two horizontal rods are connected from the MFC to the Propeller Control Unit, which actuates the pitch change mechanism inside the prop hub. The black box forward of the ECU is the Torque Signal Condition Unit. Just aft of the ECU is the oil sump with main oil filter visible - the silver cylinder, with the LP fuel filter just above it, attached to the fuel/oil heat exchanger. Just aft of that with yellow blanks installed is the tubing for the main bleed air tube, with bleed valve just visible. That tube, removed, goes to the pre-cooler, removed, below which is the Handling Bleed Off Valve (HBOV), or compressor dump valve, which opens at low rpm and is controlled by the ECU. The main bleed air line then goes to behind the engine to nacelle shut off valves, then off to the de-ice boots on the wings and tailplane and to the pressure seals in the doors. Aft of the firewall, you can't see the fuel injection nozzles and transfer tubes and thermocouples:






The rear of the engine with the after fan of the power turbine assembly visible. This bit butts up against the exhaust tubing:






The cowl after engine removal:






Looking up into the cowl sans engine, at the aft firewall and exhaust port. Note the exhaust pattern; it swirls from the engine, leaving tell tale marks on the exhaust tubing. Being a turbo prop, this is just hot air; it provides no thrust at all:






Finally, the hangar looks like this on a typical night. We can fit four Dash 8s in, with a fifth undergoing heavy maintenance in the far corner (not visible). When we have more than four aircraft, we shuffle them about - a bit of a faff, but better to work on them in our nice heated hangar than outside in the cold:






Thanks for looking. Nighty night

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## rochie (Oct 9, 2015)

Good stuff


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## vikingBerserker (Oct 9, 2015)

That looks fun!!!!!!!!!


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## at6 (Oct 9, 2015)

Interesting. I'm surprised that you don't have an overhaul facility in your country.


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## Airframes (Oct 9, 2015)

Good stuff Grant - I can almost smell the oil, even though that hangar looks spotless.


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## Gnomey (Oct 9, 2015)

Good stuff!


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## Crimea_River (Oct 9, 2015)

Interesting. Thanks for taking the time to do those detailed descriptions.


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## Capt. Vick (Oct 9, 2015)

Great detail! Look almost real! And the subtle weathering and engine detail...not bad.


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## nuuumannn (Oct 9, 2015)

> Look almost real! And the subtle weathering and engine detail...not bad.



You think I might qualify for one of those little planes, now?  Yeah, it was a [email protected] doing the engines, although I'm impressed with the drip tray and oil stained rags...



> I'm surprised that you don't have an overhaul facility in your country.



Despite the hassle, it works out cheaper to do it overseas. GE and RR gas turbines get overhauled at the Christchurch Engine Centre at Chc airport, but the smaller turbo props are done abroad. We used to use Lufthansa Technic, but changed to Standard Aero - cheaper.



> Thanks for taking the time to do those detailed descriptions.



No worries, it helps wind down after a long night at work. The great thing about doing things like this is that there's no stress, just jump in and do it and take time to do it properly. Some nights we can be rolling aircraft in and out and the pressure's on, especially when things go wrong. Also, doing a big job means less of the rats and mice jobs that involve taking longer to do the paper work than doing the job.



> I can almost smell the oil, even though that hangar looks spotless.



The worst one is Skydrol - we can live with oil, but the hydraulic fluid makes you itch and burns after awhile. The Dash is a small plane trying to be a big plane, so the hydraulic fluid is the hard stuff. Other aircraft of its size use Fluid 41 as hydraulic fluid, far less toxic and easier to work with.


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## at6 (Oct 9, 2015)

The last time I saw something like that outside of the cowling was when I was with the parts department for a local Piper Distributor back in 1981. We had a Turbo Cheyenne which chewed it's way through a C-172 wing tip because the owner misjudged the distance between his plane and the Cessna. Mechanic had to pull the engine and send it out for a "hot section" due to sudden stoppage. Also the prop had to be sent out for inspection and overhaul.


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## Wildcat (Oct 9, 2015)

Excellent post!!


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## fubar57 (Oct 13, 2015)

Great post Grant. I love looking in on other peoples jobs.




Geo


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## Vic Balshaw (Oct 13, 2015)

Nice set of pics Grant, good to see your work environment, looks nice and cosy.


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## nuuumannn (Oct 23, 2015)

Thanks guys.

This poster has been put up on the door to the heavy maintenance office; I thought it might appeal to your senses of humour.

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## Wildcat (Oct 23, 2015)

Nice!


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