Oil analyses: An IO-470 speaks

As I’ve mentioned before, the sweepstakes Debonair had a major overhaul completed in 2007, at Penn Yan Aero. Penn Yan does great work, but the then-owners didn’t fly the airplane much for the next five years. In that period of time they put approximately 28 hours per year on the airplane. Those hours most probably were local flights for currency purposes.

That’s not much time. For much of those five years it was tied down–outside–on a ramp at Hartford’s Brainard Airport. So the oil level sank to the sank to the sump in the crankcase, leaving the camshaft, pistons, valve assembly, wrist pins–the whole top end, in other words, left high, dry, and free of a proective oil coating. Well, maybe it wasn’t exactly dry up there. Condensation must have occurred as humidities and temperatures rose and fell, and the seasons came and went. Obviously, this promotes rust.

Since taking delivery of the airplane, I’ve logged about 36 hours in N75YR’s left seat, on trips to Minnesota (D’Shannon Aviation, for tip tanks, window, and gap seal installation); Kansas; New Mexico (Santa Fe Aero Services, for avionics install); Lakeland (for display at Sun N’ Fun); Newburgh, New York (KD Aviation’s paint shop); Oshkosh (for display at EAA AirVenture); and Batavia, Ohio (for Air Mod’s interior renovation).

In other words, the airplane went from torpor to serious flying. Right before Oshkosh, we had an oil change done, and an oil analysis performed by Blackstone labs at the same time. The numbers–especially for iron–were disturbingly high. Iron particles in the oil represent wear from the cylinders. Aluminum (top end components), chrome (camshaft lobes), copper (bearings and valve guides), and silicon (dirt) were also represented in elevated levels. The high lead readings are from the lead in avgas, and aren’t cause for concern. Blackstone called us to express their interest in the engine’s condition.

A meeting of the minds–Penn Yan and Blackstone–came out with a recommendation to keep flying the airplane, but to change the oil at more frequent intervals. Compressions have been good, by the way, and the engine runs smoothly, puts out rated power, and meets book performance.

This is what happens when a long-still engine comes to life. Deposits work free as moving surfaces are cleaned by fresh oil, and acids and water are eliminated by long periods of combustion.

After Oshkosh, Air Mod changed the oil. It had been seven hours since it was last changed. We were hoping to see lowered particulate levels–and we did! Here is theBlackstone report, showing the results of the two analyses:

Blackstone's oil analysis from the oil changes made on July 23 and August 12.

Blackstone’s oil analysis from the oil changes made on July 23 and August 12.

So now the plan is to keep flying (look for more cross-country flying in the coming months) and keep quick-changing the oil. We’re also installing an Airwolf spin-on oil filter (the IO-470 has a screen, not a proper oil filter) so that we can better examine the filter for particles. The filter could also help capture any older particles that have been trapped over the years. In effect, we’re flushing the engine’s oil free of contaminants. We hope.

“If I sat on a couch for five years, then got up and went to New Mexico and back, I’d be shaking loose some deposits of my own,” said Bonanza/Debonair guru Adrian Eichorn. Well put. I’ll show the next oil analysis results when the time comes. If the numbers go down, great. If they don’t, we may have to consider another overhaul–an unplanned alternative we hope to avoid.


  • Lane

    Early on is was said the airplane would keep this engine as-is, then “engine change” was mentioned IIRC. What is the plan for the engine? The IO-470-N of 260 hp. makes a great mod for this bird with a low-drama install.

    • http://www.aopa.org thorne

      True enough Lane….. but we have budget constraints that must be considered

  • MK

    Why would you give away an airplane with a questionable engine?

    • http://www.aopa.org thorne

      The issue will be dealt with.

  • Tony

    Put a new enging in the plane. Liability issues

    • http://www.aopa.org thorne

      Understood, but we will bring the engine up to specs and do what’s necessary to right any confirmable mechanical issues.

  • tony

    This is going to be a special plane. mine, mine, mine

  • BennytheBrewer

    I would like to see the new Electroair ignition on this plane and a power flow exhaust. How efficient can we make? It seems like a good investment considering our current energy environment. That would be teaching an old dog new tricks.
    I have no pretense of winning this aircraft but if I did win I would start a flying club and sell shares to help defer the cost of ownership and taxes! Would I be the first sweepstakes winner to actually keep the airplane?! We need to get as many people in the air as possible now days. Who’s interested?

    • CB

      I know for a fact that the 2001 AOPA sweepstakes Bonanza is still owned by the person that won it.

      • BennytheBrewer

        Thats good to hear! I think its the way we would all want it.

  • Bill Pearson

    change that engine.

    • http://www.aopa.org thorne

      Oil analyses are just one tool in measuring engine health. Going off and spending gobs of money on a new engine, or an overhaul, is not warranted based on a couple of samples ….


  • http://learntoflylv.com Scott Brooksby

    I think not doing the engine is a great idea. A lot of mechanics have pilots convinced that if anything out of the ordinary occurs they should immediately ground the plane and spend a fortune. This is rarely necessary. I had the same type of thing with my first engine and it flew forever on the engine that had sat for years.

    This is AOPA’s opportunity to help pilots understand that flying regularly is best, what to do if you can not, and the importance of monitoring a potential problem for while. If we are trying to stay economical, understanding when we can wait and when we can not is essential.

    On the off chance that I won the aircraft, if I had to do a new engine sooner than later, I would gladly do it without complaint. The concept of a refurbished airplane is that things are restored to their best condition based on the then most current information. In a refurbished airplane there are always things that have to work out. It is still not a brand new airplane.

    • http://www.aopa.org thorne

      Good point Scott, and I agree. We’ll be tracking this engine closely

  • Kurt Witbeck

    Well said Scott, earlier comments remind me of goverment spending, people act like it is not their money being spent!

  • Steven Koeppel

    Half the metals in probably half the time is not an improvement. Blackstone implies as much in their remarks.

  • Fred j geiger

    Since the engine has very low hours it would be wise to run it for a while and see if the metal making stops. My bet is that it would and a normal TBO would be reached

    • http://www.aopa.org thorne

      That’s our strategy for the short term Fred


  • Don Rowell

    Steven Koeppel says it right. Change the oil next at three and a half hours and you will see even more “improvement.”

    • http://www.aopa.org thorne

      That’s what we’re hoping Don

      • Steven Koeppel

        Thanks Don, Tom Horne had no idea you were being sarcastic.

  • http://www.nar-associates.com David F Rogers


    I recommend calculating PPM/hr when comparing the results for
    oil changes with different hours on the oil.


  • Rick King

    I have a 1973 Rockwell Commander 112A that has been flown only 33 (thirty-three) total hours in the last 40 years. It has been kept in a heated hangar but I have always figured that it would require a complete engine overhaul before being put back into service. Wouldn’t rust particles score every moving part ?

    • http://www.aopa.org thorne

      I suppose this would vary with the airplane, the climate, etc. In theory, the components left “high and dry” (camshaft, cam followers, valves, etc) would be most affected by being left exposed to the air. The only way to determine this would be to do a borescope exam of the camshaft and the valve train–which means pulling cylinders. It may come to this as an escalated diagnostic strategy. One thing you can do is turn the engine manually, if only to prevent corrosion points from starting due to dissimilar metals corrosion. Pre-oilers could also help keep the top end lubricated, at least in theory.


    • Dennis Fender

      Mr. King, if you’re anywhere near central Texas I volunteer to help keep the oil circulated in the Commander. I’ll even buy the gas to do it! (And lunch)

  • Charles Clark

    I purchased a 1968 Cessna with less than 2000 hours total air-time. It did have new Mellinium Heads installed at 1836 hours. During the previous 18 months it had accumulated less that 10 hours. I had the oil evaluated at the time of purchase. Iron was in the Red range at 77.8 ppm and all other parameter were normal, so I expected to install a new engine. I put 50 hours on the engine, and the oil analysis dropped to 43.2 ppm Iron. I decided to stick with it to see further results. I have had three additional 50 hours oil analysis since then and the iron has averaged 13 ppm. It appears that the lack of use and/or the realatively few hours on the new heads contributed to the high Iron ppm. I’m a firm believer in routine engine oil analysis for an early indication of something is going “South”.

    • http://www.aopa.org thorne

      I like what you’re saying Charles

  • http://WatkinsAviation Steve Watkins

    Follow the Continental guidelines, but watch for the oil pressure to slowly be less and less each flight, which indicates wear in the bearing areas. If you cannot make green arc it’s time for maintenance. Might check for valve lift every 100 or so hours to check for cam wear. Replacing an engine for metal in the oil with no other problems is a waist of money unless you are just into supporting the economy.

  • Mike Kuhn

    High Chrome was mentioned as a camshaft problem. Check to see if the cam is chrome. I don’t think so. Rings or cylinders can be Chrome. Cam and lifters are steel which can be hardened.

    • http://www.aopa.org thorne

      I believe the cam lobes are chromed. The cylinders are neither chromed or nitrided–just steel!


  • Dan Winkelman

    I am with those on here who say keep running it, keep changing the oil, and keep a weather eye on wear indicators. I’m wondering if it was properly run in after the last overhaul. New and freshly rebuilt engines will show higher-than-normal metals until they finish breaking in. It can be really disconcerting to get those first few analysis results back, but it’s normal.

    Engines do not like to sit, they like to run. Some good suggestions have been made in this comment list on things to watch for: frequent compression checks, further oil analysis, filter dissection/analysis, oil pressure, cam wear, etc.

    Run it, but watch it and be careful. Nobody wants you to have a forced landing due to engine failure.

    Fly safe!

    • http://www.aopa.org thorne

      Agree with everything you said!


  • Steven Koeppel

    Don Rowell and David Rodgers are correct. Somebody is kidding themselves if they think this engine is in good shape. If anything, wear metals are increasing. I wish I knew the time on previous oil change on 07/23/2013. I wouldn’t fly that aircraft IFR, at night, or beyond gliding distance from the nearest airport. Get with it AOPA, safety not cost should be your priority !

    • http://www.aopa.org thorne

      About 29 hours was put on the airplane before the July oil change. Long trips: SAF-LAL; LAL-FDK; FDK-SWF;SWF-FDK

      • Steven Koeppel

        Multiply the 8/12/13 values by 4 to adjust the 7 hour oil change to compare with the 29 hour change. Now tell me if you think things are getting better. If anything, the wear analysis indicates a worsening situation. High silicon usually means unfiltered air or leaks in intake. Fix that and Iron will usually drop. Increasing copper and chrome indicate scuffing parts that will only worsen.

  • http://AOPA Roger Shepherd

    I now an old pilot, use to be a bold pilot-not anymore. Your liability would be a big factor in this case. Far as the engine goes fly it but watch it closlely. Maybe for the next 100 hours change the filter every 12 to 15 hours & check it.

    • http://www.aopa.org thorne

      We understand all of this. Frequent oil changes will be the rule. An Airwolf oil filter has been installed so now we’ll have a better way to analyze the oil’s condition, as well as look for particulates in the filter element.


  • Trevor Mahabeer

    Just curious. How much does the 80 hours of corrosion/cleaning cost? Also, the refurbishing of the interior.

  • http://blog.aopa.org/sweepstakes_logbook/?p=680 Dieter

    Hi Tom,
    I also agree monitor closely. This will probably prove to be a good engine in the end once the cob webs are shaken. Probably 80 percent of the engines flying are in this shape in this economy. The oil analysis report indicates IO470 L engine which I thought has 260 HP. If not what would have to be done to bring the engine up to 260 HP if possible.

  • Scott Morton

    I think your conclusions from the quick oil changes may be wrong. The accumulation of metals is a time based function – the longer the engine runs between oil changes, the more metal you would expect – and it would be nearly straight line unless something is going bad fast. So the reduction in ppms after only 7 hours of flight time would of course be lower by a factor of 7 if the previous change was 49 hours of operation.

    We monitored our oil for years, always changing at 50 and at the annual at 25 to 30 and the annual ppms were always lower as we typically put 75 to 80 hours per year on. We were quite confused by this till we started dividing the ppm by hours on the oil . . . then all the numbers lined up, made sense, and were normally consistent!