Q: Hello, Paul. I live in South Africa, Johannesburg. I love reading your articles on engines. You have wise words. Thank you.
I have an RV-6 built by myself and my brother-in-law. We fitted a Lycoming O-320-B2C that got overhauled after 560 hours by Alton Engineering.
I believe you will be able to help me with the following:
- The engine now has 47 hours since new. The temperature seems to stay between 200° and 225° Fahrenheit. Is this correct?
- I am still using straight 100 run-in engine oil.
- I replaced the oil at 5 hours, then 12, then 20, then 31, and just now at 46 hours again. I just want to be sure with this new engine the oil and oil filter is and stays good during the break-in cycle.
- The engine starts first time every time, idle is good around 600-700 rpm.
- I have fitted a metal fixed pitch prop supplied by Van’s Aircraft.
- I have also fitted the next bigger oil cooler supplied by Van’s after five hours due to the temperature staying around 200° Fahrenheit in cruise, but it will climb to 220° to 225° doing circuits.
- When do I change to the next type of oil and what is best for this engine?
- Are the temperatures I am seeing normal? If not, what can be done to bring the temperature down?
- This engine has a conical mount. Is there a way to balance this engine better? I seem to pick up a vibration around 2000 rpm. Everyone I have spoken to blames the engine mount, which I know is true.
- There is an AP who has an electronic instrument that gets mounted on top of the engine. You then run the engine and this instrument tells you where to add some weights on the ring gear (149) to reduce the vibration. Do you know this instrument and will it be safe to use on this engine?
Collin von Ahlefeldt
A: Collin, congratulations to you and your brother-in-law on the outstanding job building this beautiful Van’s RV6.
With regard to your concerns, I can tell you that it appears all is well from the information you supplied.
Having been to South Africa, and knowing the temperatures you experience there, I agree you made the correct choice by breaking your engine in on straight weight 100 mineral base aircraft engine oil.
I also would like to compliment you on your oil change frequency during the break-in period.There is no doubt installing the larger oil cooler will serve you well, even though the 220°-225° you were seeing while doing circuits is still within the limits. As you probably know, the maximum allowable continuous oil temperature is 245° on all Lycoming engines. The temperatures you mentioned are well within limits, so dismiss any concerns you have regarding this subject.
In answer to your question regarding when to change from the straight weight mineral base oil, this may be done anytime within the first 25 to 50 operating hours or whenever the oil consumption stabilizes. I’d say you are probably ready to make the switch now if you haven’t already done so.
Because you don’t have severe swings in temperatures there, if the aircraft were mine, I’d stay with a straight weight AD oil versus moving to a multi-viscosity type oil.
I’d also recommend you locate a copy of Lycoming Service Instruction 1014, which addresses lubricating oil recommendations. Another publication Lycoming recently released is Service Bulletin 480F, which has been revised and contains much more detailed information. This is important information that should be of interest to any Lycoming engine owner/operator. Its focus is on oil servicing for all Lycoming engines.
Finally, let’s briefly take a look at the vibration issue. There is no doubt an engine with a conical type engine mount will not be as smooth as an engine that has a dynafocal type mount, but it is what it is.
My first suggestion would be to remove your prop and rotate it 180°. A quick test flight may reveal a smoother operation. I’ve seen this task eliminate a slight vibration, so it’s a simple thing to do and hopefully the results will be positive.
Should this not cure the vibration, then I’d suggest you consider having a vibration survey conducted by an experienced facility. Vibration surveys have been common in the helicopter industry for many years, but have now become popular on fixed-wing aircraft. This technology is very safe and eliminates many issues, such as baffle cracks, etc.
Collin, you’ve got a beautiful aircraft and appear to being doing everything correctly, so keep up the good work. Most of all, have fun flying your aircraft.