Good evening,

I suspect some topics related to my question will be a bit divisive, but I'd like to have a good conversation on what it takes to make a TSIO-520 go the distance. The application is a TU206G on wheels, in Idaho, so there is lots of flying between 6000-10000 MSL.

Basics like flying within the parameters of the POH, preheating correctly, proper mx, flying regularly, etc., are assumptions.

What I'm looking for are tips that are not in the POH, based on operator experience, that have proven to help the engine get closer to TBO.

Also, is there a mechanical fix for the hot start issue? Just insulate the fuel lines? Or any other mechanical tips/tricks for making the engine easier to operate or more reliable?

Thanks in advance

TSIO 520R 1981 T210: 200 past TBO and CHTs 68 plus. Sold and next two buyers still on that engine. Cessna shop added heavier starter cables so it spun faster and seemed to push fuel right past any hot air bubbles in fuel line; after all the other tricks this one was by far the best for us for hot starts. Also, ran LOP all the time unless higher than 15,000 or so- bootstrapping in hot WX= easier to manage cooler CHTs plus bonus of slight fuel savings. As stated: fly often and always preheat below 40 also worked for us. Blackstone reports were always good. We (wife also IFR pilot) owned/flew our T210 for 22 years. Wonderful plane.

Watch your CHTs, don’t be ham fisted, keep some power in on decent as to not shock cool the thing.

Hot start is just technique

Not turbo but on my 520 I’ll prime with boost till I see some fuel flow, stsrt cranking with the throttle all the way out and slowly advance it, works most times

If it’s really being a pain I’ll prime, go full throttle and mixture ICO, once it catches I’ll advance mixture as I pull back power


Read up on the cold weather supplement,

http://www.reiffpreheat.com/Continental ... %20Ops.pdf

but outside of that let the CHTs get to about 200 and oil to about 100 before you put the coals to it


Engine blankets are nice

Get a battery minder with the pig tail on the battery, if you’re not running the plane have it plugged it

Fly them every day.

Our fleet of C207s in SW Alaska have normally aspirated IO-520s. They fly clear to TBO without ever having a cylinder pulled off*. That's generally 11-13 months of daily use.

For part 135 we can't run them past TBO, which is a damn shame as most are still running perfectly and don't need oil added before the 50hr.

During the winter they are either in a heated hangar at night or have the engine heater+blanket (engine is hot to the touch).

Year round they are started and idled at 1000rpm until the oil temp is in the green before doing a run up.

Easy starts every time
Cold start:
Mixture and throttle full
Boost pump until you see 14gph on the gauge, then off.
Throttle all the way out, start cranking
Throttle in slowly. I can predict which prop blade it will start on.

Hot start is identical except boost pump is just a very short "Bzzt" (maybe 0.5 sec). No Lycoming style mixture motions are ever needed. If it's hot weather and 0.5 sec doesn't do it then use about 1 sec.

Winter operations, when approaching your destination, reduce power 1"/min down to 20". Then as needed to get 15" abeam the touchdown spot. Keep 15" (and 80kts in the 207) until you're over the imaginary fence.

The 520 is a superbly reliable engine when flown often.

* I recall seeing one engine with two cylinders off and the mechanics used it to show what happens when you don't break the engine in correctly.

I ran TSIO-520s in the 402s. We cruised at 55% pwr and leaned them to 75-100deg ROP. Easily hit TBO.

Hot start. Works for TSIO as well as IO 520s. Mixture Cutoff (With the Mixture in Cut Off No fuel should be flowing through the Divider and injectors. Throttle Wide Open (This will allow Cool Fuel to circulate through all the lines, Engine driven pump and move any bubbles back to the sumps) Boost pump On until you hear all the bubbles gone and the pump is steady. Then prime and start. This is called a Flooded Start. Mixture Rich, Throttle Wide Open, Boost Pump On High until FF gauge (This is a pressure gauge at the Divider) shows positive flow and time as necessary for engine Temp, Boost Pump OFF, Throttle Closed, Crank Engine while advancing Throttle ( The Air/Fuel Mixture in the intake tubes Leans from Over Rich to ignition point)
Cessna moved the boost pump a couple of times. From the firewall to under the floor boards in the cockpit. My poor wife with the C model 206 (Firewall mounted boost pump) Got trapped at the fuel pumps on a hot summer day because the boost pump vapor locked. Procedure above wont work if the boost pump wont grab fuel and push it. Had to talk her through (over the phone) pouring water on the boost pump. That finally worked.

I've got about 1800 hours behind TSIO520Ms in TU206G models and maintained them for 7 years in a busy missions program. Hot start is a technique as I don't remember it being an issue once you got the knack of it. I was trained by guys that had flown them a lot before I got there. Hit the boost pump for 2-3 seconds with mixture rich IIRC before trying the starter. It's been 18 years since I flew them so my memory is a little rusty on that but I don't remember it being a big issue once you learned it.

Both of our TU206G models (a 1977 and a 1979) had intercoolers and remote oil coolers (oil cooler moved into the tunnel above the nosewheel). Both mods are STC and I don't recall where we got them. The remote oil coolers helped us run the engine oil a lot cooler. Before those coolers, just using the stock ones, from climbout from about 500' MSL up to 18,000 MSL, the oil temps would run close to redline. After the remote mod, the oil temp went up about 2/3 the gauge and stayed. We always idled for a minimum of 3 minutes before shutting down to not coke up the turbo by boiling off the oil in the turbo bearings. IFR flights into our base had a minimum of 18k' to start the approach. I was in the Andes and we did a lot of flights from there to the Amazon basin jungles with most of our flights cruising in the 14k-16k' range. We serviced a couple of clinics at 14,500' msl field elevation.

For maintenance we usually did a pre-emptive top overhaul which usually happened around 1,200 hours because right around then we'd get a cylinder with low compression by valve leakage. I don't recall now but I believe it was the intake valves got a bit mashed at the seats. When we would get one cylinder down, we'd pull all 6, grind and lap all the valves and seats then run to TBO and a bit beyond with no trouble. We never had excessive oil burn even after TBO. IIRC TBO is 1,600 hours and the authorities we worked with would allow us to go 10% over TBO (1,760 hrs) then a mandatory overhaul.

HTH
Jaydub

Thanks guys, if I can ask one follow-up question: what is "bootstrapping?"

"Bootstrapping" is when the turbo control system can't hold constant upper deck (turbo output) pressure. It appears as non-constant manifold pressure vs altitude, as if the engine were normally aspirated. The pilot has to push throttle to keep MP up in climb and pull it in descent.

After setting climb power, you should see constant MP up to 12000-15000 feet, depending on OAT, fuel flow, controller setpoint, and other stuff. Above that the system will always bootstrap because it can't pump up the thinner air enough to hold the upper deck setpoint, which I think for your engine is about 35".

The name refers to "pulling itself up by its bootstraps". When the controller doesn't hold constant upper deck, the system is positive feedback, so the more power the engine makes, the more mass it runs through the turbo, so the higher the turbo output, more MP, and more power, etc. So at high altitudes, without touching the throttle, you may see MP wander by a few inches as the system bootstraps up and down.

DaveF knows his stuff.

Put 2,200 hours on a IO-520 in my Bonanza. WONDERFUL engine! I flew it LOP. I went back and forth with Gami injectors to get it right, which was well worth the effort and I would suggest you do the same. The engine was well beyond TBO when I bought a new IO-550 and then put another 2k hours on that engine, flying it exactly the same as the 520.

Bottom line, and consistent with the comments above, fly the airplane A LOT! I used mine as a daily commuter and never had any issues with cylinders/valves, etc. I went through several starters and replaced several mags (basically replaced the accessories as they wore out), but never had any issues with the core engine.

Listen to the advice in the above posts because it is spot on!

Jim

Great info thanks. A dash of fuel pump and some sweet talk always works for hot start. Any comments regarding optimal RPM for longevity % power charts aside? Sorry not turbo specific...or is it? IO-520D. The thing seems to run very smooth from 2300-2500 but is considerably faster on the latter with my short 3 blade. Fuel burn is not the major concern just want the engine "happy" and go FAST. Also, would not running faster skew the data on TBO as most people are using mechanical tach time? I have a probably misguided notion that a heart has only so many beats in its life.

Lots of great advice, guys. Thanks a ton!