October 4, 2012 at 4:10 pm #83897
Dear TTCF Members,
This is my first post on TTCF. I am currently looking to move from a C310 that I have owned and flown for 12 years and some 1400 hours, to a C340.
In reading some of the material posted on this site my question is this. Will the TSIO-520-NB go to TBO assuming the are treated and flown professionaly or are they prone to needing OH prior to making TBO? What I read indicated the 520-N were TBO eaters but not with the NB designation. Coming from the world of IO-470-VO engines that will run and live forever if cared for correctly, I realize I am stepping into a whole new environment. The specific airplane I am looking at had both engines overhauled by a quality shop in 2006 and currently have 270 hours on them. Looking at the logs from the last annual the compression seems low. My mechanic is going to do a compression check to verify the readings from the airplanes last annual. Doing the math on the hours since overhaul, the airplane has flown just under 50 hours per year. I know that to be the case with most of the flights being in the 3 hour duration.
Van Nuys, CaliforniaOctober 4, 2012 at 7:34 pm #96824
I am not a guru on engines, just have a plane with them on the wings. I bought factory reman engines for my 340 when I bought it and ran them both 1610 hours w/o having a cylinder off either of them. I run them ROP as I don’t understand nor have I been trained on the LOP operation. And I averaged 200 hours a year during that run.
That said, when I was at the TTCF Engine Seminar last Spring, Tony said; they “will not make TBO w/o cylinder work”.
So it is possible (my experience), but I guess not to be expected.
Good luck on your search for a new plane.
JimOctober 4, 2012 at 11:48 pm #96825
Thank you that is a big help. I fly very concervatively even without turbo charged engines and it shows. 2000 hours on my 470’s with no cylinder work and no oil burn to speak of. I realize these engines are an entire new level however, I still believe one pilot and good engine management is the key. My question however is answered in that one can expect top work prior to TBO. Still very interested in the 340 though. Have always loved the lines and the feel of the airplane. Most trips for me are 200 to 500 nm and about 130 hours per year. Once you go up high in fast airconditioned comfort, it is hard to go back. Now that I have, I am hooked.
Thank you again!
DaveOctober 5, 2012 at 1:21 am #96826
Hi Dave and Jim,
Jim, I’m sending you a dollar, would you buy me a lotto ticket. You may be the only person on earth that has owned a TSIO-520N or NB engine without needing cylinders. I have found that the weak link in these engines are the cylinders and for the really unlucky, the cases. The bottom of these engines will easily pass TBO and they are even fine through 2000 hours. The cylinders, though, are really crap. They either need valves, guides or they get cracks. You should plan on a top at 800-900 hours. When you start seeing a good bit of oil on the landing gear and doors, you will know that at least one cylinder or the rings on its piston are getting weak. (they all have some oil on the main gear) Also, at every oil change your mechanic should carefully inspect the cylinders for cracks around the spark plugs and if plugs are removed they are carefully replaced. Without trying to scare you, if you own a turbo charged twin Cessna you need to be prepared to put a cylinder on at any given time. That being said, I have owned 3 different turbo charged twin Cessnas and have loved everyone of them, even with their lousy cylinders. In fact, I will never own a normally aspirated airplane again.
SandyOctober 5, 2012 at 1:31 am #96827
You will definitely not find the TSIO-520s to have the reliability of your IO-470s.
That said, a lot of it does have to do with power settings. Many people are of the “I bought this airplane to go fast” mentality. Nothing wrong with that, but the engines do tend to not last as long when you do it that way. You would likely get good service out of the engines if you operate at conservative power settings.
One of my friends recently got the engines in his P-Baron overhauled at 2200 or 2400 SMOH (I forget which exactly). He bought the plane with 1000 SMOH and it just had a top overhaul done. Not a single cylinder touched between 1000 hours and overhaul. He flew the plane LOP at about 65% power. I believe the P-Baron engines are pretty similar to the 340 engines.October 5, 2012 at 5:46 am #96828rwelshParticipant
Cylinders have always been the bugaboo on these engines. All three cylinder manufactures have had recalls and SBs about bad cylinder construction. You can have the cylinders pass a compression test when it is down to around 50/80 according to TCM’s Service Bulletin. The turbo blows a lot of air into the cylinders so some leakage doesn’t show when flying except above FL230 you may run out of boost in a weak engine. But you can run the RPM up to 2500 or higher to get more mass airflow through the turbo to maintain power in the upper flight levels. If you run LOP, then you will most always need a higher RPM above FL230 unless the plane has RAM 7 turbos on it as these maintain boost at higher altitudes. If the OAT is colder then standard, you can maintain boost up higher, but usually the OAT is hotter then standard which hurts performance up high.
The other problem with these engines is the lifters and cam. This occurs mostly in coastal areas on planes that are not flown regularly as the oil flows off the cam lobe and lifter face with non use and then corrosion takes hold. It is possible to remove the push rods from a cylinder and then remove the lifter and observe the cam lobe and lifter face. I imagine some sellers would not approve of this procedure as it involves some baffle removal and other things.
Not to start an argument, but owners using LOP seem to get more hours out of the cylinders/engines then those running ROP; this assumes you know how to set up for LOP running and you have a good engine monitor that you know how to use and interpret. I have 1150 hours since I field overhauled the engines and I still only use 1 quart of oil between oil changes, and I have run LOP since 20 hours after the overhauls. I run LOP at all altitudes even down low below 1,000 feet. I just looked at the last 10 flights on my Insight G3 engine monitors and see I am using 74 percent power using a little over 15.2 GPH with CHTs never more then 390dF and getting over 200 KTAS. LOP is not for the inattentive type of pilot as you have to be engaged with the engines.
Good luck in you 340 hunt. I previously had a 310 also, but will never go back even with the extra expense of a pressuized turbo plane.October 6, 2012 at 12:58 am #96834quote RWELSH:
This has been my observation as well, and has some good science behind why. But more important than ROP or LOP is running your engine “right”, which means at a mixture strength that allows sufficiently low temperatures and minimizes peak cylinder pressures. This can be achieved ROP or LOP.October 6, 2012 at 3:05 am #96837
I think more than one supplier has had issues with the 520 and 550 cylinders. Problems include valve lifters, pushrods, valve guides, etc. If your engine does not have one of these slow to manifest defects then your odds are much better of seeing TBO.
Aside from that, keeping ahead of corrosion and keeping cylinder temps below 380 either ROP or LOP are good ways to prolong life. Another thing to consider is the accessories are working hard in a pressurized turbo twin and you may not get to TBO on some components like wastegates, tailpipes, elbows, etc. I would also suggest that you will not get full TBO life out of your vacuum hoses as they route right by the exhaust and since they contain nothing (or air) they conduct heat very poorly. Mine were hard as a rock and crumbled when moved (caught at this annual). I ended up replacing them and also replacing the fuel inlet/return with the brown teflon hoses.
Other components working hard are the mags and harness.October 8, 2012 at 4:00 pm #96851
Thank you to all who replied. I am truly grateful as the information helps to make an informed decision. I am only sorry I did not sign up with TTCF 12 years ago when I bought my 310. To be sure, that will not happen again!October 9, 2012 at 12:38 am #96856
Sorry, I’ve been off line a lot, but here’s my take on 520’s… Mine are TSIO-520 NBcEB, per RAM 1 STC. I don’t have any idea how these engines were operated for their first 600 hours. They were torn down and inspected after a taxi gear collapse on a 310R, IIRC. Previous owner (my AP/IA, Part 135 operator), bought and installed them on what is now my airplane. His pilots flew them ROP, best power mixture, as I have been for the last 9 years. The engines are near 1400 hour TBO. None of the 12 Superior Millenium cylinders have ever been off the engines. Compressions run high 60’s low 70’s and oil consumption is a quart of AeroShell 15/50 in about 12 hours. Oil analysis remains normal.
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