Posted: 5/3/2011 12:31:41 PM EDT
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Alright, so I realize that one can be nice to your plane's engine and it should be nice to your wallet in return. I'm looking for general pointers in that regard.
I've already heard: -Keep the oil level above the minimum (but don't top it off fully unless you like blowing out excess) -Don't cold shock an engine when descending from altitude -Warm up an engine before starting on cold days -Keep the run up short and preferrably nose into the wind -Adjust throttle gently, not suddenly -Don't start the engine just to taxi to the pumps, use a tug whenever possible Any other pointers? I wonder if cruising at reduced throttle settings will help extend engine life or not. Is it really any easier on the engine to run at 50% versus 75%? |
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The best advice is to run it at the right mixture.
Most general aviation and even professional recip pilots run WAY TOO RICH. There are some wonderful articles by John Deakin on his Pelican's Perch column on Avweb. They are a must read. The engine should be run at the right temps, not too hot, not too cold. An aircraft engine is just an air cooled engine, nothing special... Just expensive. Basic engine practices apply. -Let the engine warm up a bit before revving it up. Piston speed and surface speed of the bearing surfaces to the bearings on a cold engine with cold oil will hurt things. -Run at the right mixture. A clean burning engine will run smoother, more efficiently, with more power and less deposits in the engine. -In my experience with light twins and singles, cold shocking engines is not that serious of an issue. Especially if the engine isn't at peak CHT and EGT's anyway. If you are near the say 400F max temp for an O-360, I would be concerned anyway, but would try to cool it more gently than normal. If I am in the 300-330 range I am usually in, just dump the power and go down. -Engines have a happy region for burning oil. Most air cooled recips burn about a quart per 10 hours or so. This is good, and normal. You don't need to overfill, but you will find a point where the oil consumption is pretty steady. For example, the cardinal I fly a lot likes bewteen 5 - 6.5 qts. If you put more in, it will use oil down to 6.5 qts much faster than the 1 qt/ 10 hours. I try to stay at the high end of 6.5qts. -Get an Engine monitor. Otherwise you are literally flying blind when it comes to mixture settings. -Read, and re read John Deakins articles. They are awesome. Hope this helps! -CSM ETA: Directory of Pelican's Perch Articles John Deakin's Engine Related Articles Read the "Where Should I Run My Engine?" articles. The others are fun as well. |
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What airplane and engine is this in?
The 50% power and 75% power argument depends on the engine itself. From what I have seen, if the manual says run at 75% power except on take off, I would do so... But for me in Colorado, I am almost always near that manifold pressure for a sea level rated engine due to my pressure and density altitude. |
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Oil is the cheapest thing you'll ever put in an engine, so use quality oil and change on schedule. Also manufacturer recommended additives tend to work in my experience - we had one of the infamous O-320-H2AD engines that went 3000 hours on lycomings recommended oil additive and still had great oil and cylinder pressures before we said enough was enough and overhauled it. And that engine spent most of its life in a part 141 flight school.
initial break in procedure for a new engine or one just out of overhaul is important, and varies a bit with the cylinder treatment used. In many cases babying the engine excesively in terms of using overly low power settings excessively during the initial break in period can cause the piston rings to fail to seat properly. Most of the stress in a reciprocating engine occurs during changes in power settings, so avoid them when possible. During my commercial training, one instructor in paticular focused on flying approaches with an absolute minimum of pwer adjustment - focusing on proper planning and configuration to make one power reduction from cruise, then the final cut on landing. The application is admittedly limiited in the real world but it does improve the ride for the passengers and the general concept tends to increase engine life by both reducing power changes and keeping the engine warm on descent by encouraging longer well planned descents under slightly reduced power settings. (For those times when a less than wonderful ATC will let you do something other than dive bomb the outer marker). An oil analysis becomes a very useful tool to develop and identify trends that then allow you to spot something going wrong in the early stages before the engine starts making serious metal. A pre-oiler can be a real asset in terms of reducing the wear that occurs during start up, especially for things like taxing to the fuel pumps, parking spot, hanger, etc. A pre-oiler also does not have to be overly complicated - just a fairly small accumulator bottle plumbed into the system and a push rod or solenoid operated valve to capture pressure at high power settings to store until the next start up when the valve is opened to pressurize the system and send oil to the bearings. Some aircraft struggle to stay cool when the air temps get above 90 degrees F, so in hot weather planning early morning departures can help reduce wear and tear and thermal stress on the engine. Similarly, turbo charged aircraft can also be heat sensitive and adding an intercooler/aftercooler really helps not only keep the engine cool, but also get greater power and fuel efficiency out of the engine. |
| In my opinion excessively reduced cruise power settings are not kind to the engine. They increase the time on the engine over any given distance and air raft engines are rated for a max continuous power where they would theoretically run to TBO ( given proper mixture, proper cooling and periodic oil changes. |
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Regular oil changes, proper leaning, keep it clean and avoid jockeying the throttle. Running at lower power settings won't really get you anywhere because these engines are designed to be run at high power settings for long periods of time.
Touch and goes are probably the hardest thing an engine has to deal with. |
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Does your ENGINE START checklist tell you to OPEN THROTTLE SLIGHTLY? How much is your "Slightly"? We had a flight school. Uninitiated students and instructors would open the throttle different amounts because their "Slightly" was different. Most would cause the engine to idle at around 1200 to 1500 rpm until they got to the part of the checklist that told them warm-up or idle. Pilots are trained to look for oil pressure indication within 10 seconds and pressure in the green by 30. Oil pressure is not an indication of oil flow. Cold engine oil has to warm up in the bearings before it can flow out and allow new oil in. The oil leaving the crank and rod journal bearings is what lubricates the cylinder walls and cam lobes. Getting back the the SLIGHTLY OPEN subject, I taught all the instructors and told them to teach their students to leave the throttle closed while starting and opening it only enough to disengage the starter and keep it running for the first 30 seconds. THROTTLE CLOSED is the same for everyone (except the hardheads). The goal was to reduce piston scuffing and cam loading until oil flow from the bearings is established.
The BEST way to get your engine to and probably beyond TBO is to FLY the airplane often, at least 100 hours per year. 200 is better. Get the oil changed on schedule, watch the temps, no cold shocking, and get 100 hr servicing/ inspection on the engine (plugs, mags, baffling, cowling off) |