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Care and Feeding of Lycomings

Eustace Bowhay, Blind Bay, BC
Weíre very fortunate to have Eustace in the Western Canada Wing, and on the RV List.  His is the sort of knowledge and understanding that only comes through years of experience.  This article is a slightly revised version of one of his many excellent posts to the RV List, in which he answers questions from other builders.óWebmaster


After getting out of the air force, in 1945, I became a part owner in a small charter and flying school operation, and continued to be involved in commercial aviation until retirement.  With the switch from the airforce paying the bills to me paying them I really got interested in how my engines were being handled.  It didnít take long to see the difference in costs between an engine that was carefully handled and one that was handled by an inexperienced pilot or hot rodder.

My priorities have always been safety first and costs second, and over the years it became very plain that the best and cheapest way to accomplish this was to start out with a new engine or a premium overhaul and donít cut cornerís under the cowlings.  After a few years I finally settled on the following procedures and found them to do the best job.

These are the power settings and handling procedures I have used on the Lycoming O-540, O-360, and O-320 engines over the past thirty years or so.  I have found them to give the best combination of long life, speed versus fuel consumption, and, most importantly, no engine failures.  All of my life my engine handling priorities have been:
 

1. Do the best you can to prevent an engine failure.

2. Keep engine operating cost as low as possible by having every engine run its full time between overhauls.

3. Avoid propeller damage during ground running, and try to cause the leased amount of disturbance to others from noise and prop wash.

4. Make maximum performance a consideration only when conditions warrant it.
 

In my opinion, ďengine handlingĒ begins when you first decide to start the engine.  So these are the rules I have followed.
1. Never attempt a start below freezing without pre-heating.  Learn how much prime is required under various conditions to start in, say, three or four blades.  Never prime with the throttle.

2. Keep engine RPM to 1000-1200 for a few minutes, monitoring oil pressure.  Keep under the red line.  You may have to drop below 1000 RPM initially, if the engine is started close to freezing with heavy oil, to keep oil pressure within limits.

3. Move to the run up area and, assuming one is on pavement, warm up into wind at 1400 RPM, to 100-120 degrees oil temperature.

4. Check the mags (or electronic ignition) at 1700 RPM. In the case of a constant-speed prop, exercise the prop a couple of times with a 300-400 RPM drop.  I donít go above 1700 for a mag check, unless something shows up, for the good  of the prop.  Going into grass or gravel strips, if I have any concerns about prop damage, I will check the mags in the circuit before landing and then just check for a dead one prior to take off.

5. Take off at full throttle and, in the case of the RV, climb out at say 110-120 indicated.  As soon as comfortable, throttle back to 24-25 inches of manifold pressure and, in the case of a constant speed prop, reduce to 2400-2500 RPM.  I have always made it a rule to keep full throttle operation to one minute, maximum, unless circumstances dictate otherwise.

6. Continue climb-out at these settings until reaching desired altitude, starting to lean at 3500-4000 feet, and keeping well on the rich side of peak.  On reaching cruising altitude, level off and cruise at 2400 and 21-22 inches manifold pressure for say 5 minutes, to stabilize temperatures.  Then lean to peak on the hottest cylinder, less 50 degrees on the rich side.

7. Plan your decent to maintain 400-500 FPM at say 18-20 inches manifold pressure, gradually reducing to say 14 inches on arriving at circuit height.  This cools the engine gradually (prevents shock cooling).  On levelling out in the vicinity of the airport, you can reduce power as appropriate to maintain the speed you desire.  The speed is now low enough now that this power setting will keep the engine temperature okay.  Another reason for restricting descents to 500 FPM is for passenger comfort.  I have found that people who donít fly very often have sensitive ears, especially if one has been at a high altitude for an extended period.  This means that if you have to let down 7000 feet you have to start the let down in a RV roughly 45-50 miles back.  Using this method assures the proper control of engine temperatures and also allows for immediate shut down of the engine after landing.

All of the above RPMs pertain to a constant-speed prop, which will be turning 2700 RPM in full-fine for take-off.  I have no experience with a fixed-pitch on an RV but, in talking to others, procedures should be the same.  The difference would be (in the case of the new Sensenich prop for the O-360, for example) that the RPM at the start of take-off would be somewhere around 2200-2300, increasing with airspeed until reaching around 2700 in level flight at critical altitude.  I believe, for the good of the engine, it should never be operated over 2500 RPM continuously which, with the Sensenich prop, would mean reducing the manifold pressure to around 20 inches.

The Lycoming manual says not to operate at over 75% continuously.  This equates to around 2400 RPM and 24 inches.  The recommended TBO is 2000 hours, and this can be achieved if the aircraft is flown on a regular basis (at least every two weeks) and cruised at 65% power.  This has worked for me.  I have never had to change a cylinder on a Lyc, all have run their full time, and Iíve never had one quit except for fuel starvation.

Using these settings I ran nine light twins with O-540s and IO-540s for several years, each one flying 1000-1100 hours a year, without a single cylinder change and with every engine reaching itís recommended TBO.

 Restricting RPM on the ground to 1000 or so will keep prop damage to a minimum.

Really, what all this boils down to is to use 75% for climb and as close to 65% for cruise as you can get.  The rest is just common sense.
One need not feel restricted by these procedures.  If you need it, use it.  The small Lycs are famous for their reliability, but every time one strays from the above it takes a bit away from safety and increases the costs.

Here are a couple of items I have picked up over the years as to the maintaining and handling of Lycomings.  While we are talking about Lycomings in particular, these observations would apply to most naturally-aspirated, opposed engines that I have had experience with.

Replacing the Crankshaft Oil Seal

I donít recommend stretching the new seal over the prop flange, due to the stress on the seal.  The preferred method is to use the split seal (P/N LW11997).  This seal has no spring and should be installed using 3M sealant #847 (Rubber & Gasket Adhesive).  Thoroughly clean the seat and prep with MEK or acetone, so that the new seal will seat properly, and apply the adhesiveóa cotton swab works well for this.  Be sure to coat the area of the crankshaft contacts the seal with engine oil, so that the new seal is not damaged on start up before it gets lube from the engine.  This seal, installed in a careful manner, should not  be more prone to leakage than the one-piece.

Crankshaft Plugs

Regarding service bulletin 1435, I believe that the new engines, as purchased from Vanís, are set up as they are so they can be run either fixed-pitch or constant-speed.  You must make certain that your engine is set up properly for the application you have chosen.  There have recently been several posts referring to forced landings caused by blown crankshaft plugs.  When the front plug blows out, all oil is lost in a matter of minutes and oil covers the canopy, making a forced landing necessary yet extremely difficult.  Bartís engines are set up per your instructions (fixed-pitch or constant-speed) so this problem will not occur.
The line from the accessory case to the front is for a constant-speed application.  The flow of oil through this line is controlled by the governor.  Iíll have more on this in another post (to the RV ListóEd).

Running Without a Prop

Never run an engine without a propeller.


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