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Eustace Bowhay has a vast amount of experience operating piston engines - he flew professionally for decades, and amassed tens of thousands of flying hours. He has learned a lot over the years, and occasionally offers his Pearls of Wisdom on the RV-List. I was recently reminded of this RV-List posting that he made back in 1999. The following recommendations for piston engine operation are posted with his permission. You can find more gems from Eustace Bowhay at the Van's Air Force - Western Canada Wing


From: "Eustace Bowhay"
Subject: Engines-Care and feeding of Lycomings
Date: Jan 19, 1999

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 air force paying the bills to me paying them I really got interested in how my engines were being handled. It didn't take long to see the difference in costs between the 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 don't cut corner's under the cowlings. After a few years 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 O540,O360. and O320 engines over the past thirty years or so and found this 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 a engine failure.
  2. Keep engine operating cost as cheap as possible by having every engine run their full time between overhauls.
  3. Avoiding propeller damage during ground running and try to cause the leased amount of disturbance to others from noise and prop wash etc.
  4. Max performance was never a consideration unless conditions warranted it.

In my opinion engine handling starts when you first decide to start it. 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 red line. May have to drop below 1000 initially if engine is started close to freezing temps with heavy oil to keep oil pressure within limits.
  3. Move to run up area and assuming one is on pavement warm up into wind at 1400 to say 100-120 degrees on the oil.
  4. Then go to 1700 and check mags and or electronic ignition. In the case of a constant speed prop exercise a couple of times using a 300-400 rpm drop. I don't 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 on landing and then just check for a dead one prior to take off.
  5. Take of at full throttle and in the case of the RV's climb out at say 110-120 indicated. As soon as comfortable throttle back to 25-24 in manifold pressure and in the case of a constant speed prop would reduce rpm to 2500-2400. I have always made it a rule to keep full throttle operation to one minute max unless circumstances dictate otherwise.
  6. Continue climb out at these settings until reaching desired altitude starting to lean at 3500-4000 ft keeping well on the rich side of peak. On reaching cruising altitude level of and cruise at 2400 and 21-22 ins manifold pressure for say 5 min to stabilize temps. Then lean to peak on the hottest cylinder less 50 degrees on the rich side.
  7. Plan descents to maintain 400-500 ft per min at say 18-20 inches manifold gradually reducing to say 14 on arriving at circuit hight This is done to cool the engine gradually or as we say prevent shock cooling On leveling out in vicinity of airport power can be reduced to what ever to maintain desired speed. Speed is now low enough that this power setting will keep engine temp OK. Another reason for restricting descents to 500 ft per min is for passenger comfort. I have found that people who don't 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 say 7,000 ft one has 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 engine after landing.

All of the above rpm pertains to a constant speed prop which will be turning 2700 in full fine for takeoff. 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 O360 for example) the rpm at start of takeoff 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 continuously which with the Sensenich prop would mean reducing the manifold pressure to around 20 in. The Lycoming manual says not to operate at over 75% continuously this equates to around 2400 and 24 inches. The recommended TBO is 2000 and this can be achieved if the a/c is flown on a regular basis (at least every two weeks) and cruised at 65 %.

This has worked for me. I have never had to change a cylinder on a Lyc, all have run their full time and never had one quit except for fuel starvation.

Using these settings ran 9 light twins with 0540's and I0540's for several years each one flying 1000-1100 hrs. a year without a single cylinder change and everyone reaching it's recommended TBO.

Restricting rpm on the ground to 1000 or so will keep prop damage to a min.

Really what all this boils down to is 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 Lyc's are famous for their reliability but every time one strays from the above it takes a bit away from safety and increases the costs. If I don't get kicked of the list for this post will try one on picking and caring for your engine in the next few days. Fly Safe

Eustace Bowhay -Blind Bay B.C

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