John deakin manifold pressure switch

I think the other thing we have to assume here is that the pilot actually does indeed own the engine. I own several aircraft and as an engineer would be aghast if I discovered some pilot had been experimenting after reading something on the internet. Pilots have very little technical knowledge, period. The CPL syllabus is little more than a little useless theory and basic principles of a piston engine.

It is pretty obvious from other threads, plus my own experiences, that the rating training takes it little further. More often than not it is a POH quiz. I have stated here before that a LAME would never look in that handbook for anything engineering related to the aircraft. The owner, Chief Pilot and Chief Engineer normally agree on an engine operating policy for the company.

If a pilot has a good idea on how to operate the engines a little different then I am sure the management would love to have the opportunity to discuss it. We have recently seen a pilot accept a 29" Take-off on an aircraft without any consideration to the induction flow on an engine with an inop turbocharger. The Chief Pilot, and others, rightfully assume the aircraft is being operated iaw the procedures and guidelines.

Just a thought. IBG If you are taking the time to read John Deakin's web articles then you understand that to operate an engine as he suggests you also need to have balanced fuel injectors and an all-cylinder monitor. To operate without these is courting disaster. Very, very few operators have bothered to spend the money to equip their aircraft with the necessary equipment and, therefore, to operate LOP is to invite a very short career in aviation.

In fact, most operators want their aircraft operated in accordance with a standard, many of which are crazy like operating 75deg ROP but it is their train set you are playing with and they set the rules. By all means discuss what you have read with the CP and the CE but be prepared to hear a lot of old wives tales about engine management, they are rife out there.

In my experience I have only worked for one operator and met another who have equipped their aircraft appropriately and operate LOP. I have also read of another couple or so operators on this forum who operate LOP. They are rare in the commercial world but a growing number of private operators are picking up the trend. Find More Posts by PLovett.

Tee Emm. By all means discuss what you have read with the CP and the CE but be prepared to hear a lot of old wives tales about engine management. You might be uncomfortable with the thought of actually doing some of these things to your engine - and that's fine - but I ask that you visualize them as a mind exercise and think about them, please.

This entire column will deal only with normally-aspirated engines - those without superchargers or turbochargers. I'll be dealing with the fire-breathers in another column. Leaving aside the issue of whether this is really a good procedure, let's assume you take off and dutifully pull the throttle back from about 29 inches, to exactly 25 inches.

Then you pull the prop control back from 2, to 2, Do you understand clearly why that slight rise occurs? Question: Suppose you leave the throttle wide open after takeoff, and just reduce the RPM from 2, to 2, usually a better choice in the big-bore flat sixes. What would you expect to see the MP do, and why? Question: Suppose you do a full-power runup in position before releasing the brakes another bad procedure, but never mind.

You note the MP and release the brakes. What will the MP do during that takeoff roll and the early climb, and why? Question: Do you know in general where the "sensor" is for the MP instrument, and how it works? Which would you think is more stressful to the engine's intake manifold plumbing: a power setting of 12" MP in a power off descent, for example , or 30" at takeoff power?

How is that pressure transmitted to the instrument you're reading? Question: Your airplane is sitting at rest, engine not running, at a sea-level airport. What should the MP show? Suppose you're parked at an airport at 5, feet above sea level; what MP indication would you expect? What else can affect that reading? Suppose you know what it is supposed to show, but it's two inches low in a airplane you've never flown before?

What effect would that have on your flight? Would you depart with it showing that error? Could you correct for it? Question: Suppose you start the engine and idle at 1, RPM to warm the engine. What will the MP show at sea level, or at that 5,foot elevation? Suppose you just happen to know the answers to these two questions in your own airplane, and one fine day you notice the MP is three inches higher than normal at 1, RPM while warming up?

What would you think? Suppose the MP was lower than normal; can you think of a possible cause for that? Question: Suppose you're cruising at 10, feet, full throttle , 2, RPM, and you cycle the prop between 2, redline , and the lowest it will go, perhaps 1, RPM. Question: Finally, suppose you're sitting in the runup area, ready to go, and you notice an audible whistle coming from the engine.

What would you suspect, and what would you do about it? First, let's get rid of this idea of "pressure," because what the MP instrument of any normally-aspirated engine really shows is lack of pressure. In short, with the engine running, the MP gauge is always reading suction - it's just marked with numbers that don't make that obvious.

I have deliberately made this a very primitive schematic, something I call a "concept schematic" in my ground school classes. I've left out everything that is not essential to this discussion, and have drawn a very simple one-cylinder generic induction system. In real engines, of course, there are multiple cylinders, curving ducts, many more parts, carburetor heat or alternate air, etc.

The ambient air has equalized in all parts of the engine portrayed here, represented by dark blue. I've shown the throttle yellow fully open here, but with the engine at rest it doesn't matter - even with the throttle fully closed, there's enough of an opening for air to get by and equalize. The throttle never really closes all the way - a "fully-closed" throttle must still pass enough air for the engine to idle.

In this picture, the air pressure is at ambient pressure in the intake, in the induction plumbing, and in the combustion chamber. This will show on the MP gauge as I know, it's hard to read it that accurately on the usual instruments, but you should see it very close to If the airport is located at some higher elevation, the MP gauge will show an inch less for each thousand feet above sea level.

This rule-of-thumb is close enough at normal airport elevations, though it breaks down at altitudes above 10, feet. It is a good habit to note the MP gauge reading before engine start, and do a quick calculation to see how close it is. Set your altimeter to the field elevation, note the altimeter setting in the Kollsman window, subtract one inch per thousand feet above sea level, and your MP gauge should show very close to that value with the engine not running.

At a 6,foot elevation airport, for example, set 6, on the altimeter, read say Anything else is an error in the instrument. At that 6,foot airport, suppose it actually reads That would indicate that for any power setting you want, you should set the MP one inch low to correct for that error. Mail will not be published required. Touring Machine Company.

Atmospheric River ». The content on this web site is provided for your information only and does not purport to provide or imply legal advice. The TCM IO is sometimes an exception to this, as some models have an "altitude compensating" device. In my experience they don't work very well, and I have mine tweaked to not do very much, leaving mixture control to me.

Just how to do that leaning for takeoff will produce heated debate in any airport lounge. But it's not that hard! That tells you that the mixture setting isn't critical - we just need to get it in the ballpark. All we need to do is get rid of some of the "extra enrichment" and we'll be somewhere on the flat part of that curve, and that's about as good as you can do.

Personally, I just go full forward with everything, then on the roll, I grab the mixture control and make a gross movement "too far," feeling for the power loss, then I shove it back in to the point where it "feels good," and let it go at that. We do not need to be super-precise here! Isn't that simple? The momentary "too lean" mixture won't hurt a thing, especially at the high elevation when the engine is putting out a lot less than full rated power.

To pound on the poor dead horse one more time, y ou are not "saving" an engine by using less than full power for takeoff, you are probably hurting it! All high-performance aircraft engines have some means to greatly enrich the mixture at takeoff power. When you attempt a takeoff at partial power, you often defeat this, and both EGT and CHT will be higher, often much higher before the gear comes up.

Full power will also get you higher, faster, sooner, and this is good from a general safety standpoint. Also, CHT rises continuously throughout the takeoff in all engines, because at low speed, there is insufficient airflow for cooling. The quicker you can get to an airspeed that does provide good cooling, the sooner that CHT will stop rising, stabilize, and even start down again.

The operators of one large warbird persist in taking off with reduced power, and incur the double whammy of slow airspeed acceleration on the runway and a less-than-optimum mixture, leaving them looking at redline CHTs by the time the gear is coming up. They "just don't get it. Partial power takeoffs in a multiengine aircraft are really dumb, because performance is greatly reduced, and the power setting greatly complicates the engine failure procedures.

You may think you're good enough to add power on the good engine while simultaneously handling the failure of the bad one, but trust me, you're not. You'll blow it every time. Again, you do not hurt an engine by operating it at full takeoff power as specified by the factory! This will generally keep the engine cooler. The only case I know of where reduced power thrust is safe and useful is in jet aircraft, where the CHT problems do not apply.

The fuel control units are so good that proper mixtures are maintained at all settings, and the aircraft have such an excess of thrust that the engine failure case is near-trivial. In fact, when briefing a "reduced thrust" takeoff, I make it very clear that if we do lose an engine, we will normally NOT advance the thrust on the others at all. If that doesn't seem safe, we go to the next higher available thrust setting.

Oh yes, that takeoff CHT question above? CHT will go higher on a cold day. This is because the normally-aspirated engine produces more power with cold air denser air, more fuel flow , and even more importantly, the engine is producing that slightly higher power at a leaner mixture more air, same fuel. More power and a leaner mixture equates to higher CHT.

This normally overrides the small effect of colder cooling air. My pet peeve in climbs is using too low an airspeed. I think it's stupid to climb that slowly in any airplane including jets, just so I offend everyone here! Yes, they may remain within limits, but why get any hotter than necessary? Additionally, the nose will be so high you simply cannot see where you're going - you're blind to traffic that may very well be in your path.

Finally, I firmly believe that if a total engine failure occurs at 95 knots in a Bonanza below a few hundred feet, most pilots will stall before they can get the nose down enough to maintain flying speed. If they just happen to succeed at that, they will probably end up so slow and descending so steeply that there isn't enough energy left to flare.

A crash, and an ugly one, is all but inevitable. At such low speeds, with the usual nose-high attitude, a recovery from an engine failure is very nearly an acrobatic maneuver, and not one pilot in a thousand has practiced it with any realism. It's a bad deal. For this reason, I prefer to see a very early shift to a higher climb speed once real obstacles are cleared.

In the absence of real obstacles , I set up a gradual climb right from liftoff, pulling the gear up as soon as I am well clear of the ground Oh, boy, I'm gonna get mail on that one! Hmm, might be a good subject for a column? This gives much better cooling, much better visibility, and makes the engine-out case far more manageable single or twin.

Yes, yes, I know, I'll be at a slightly lower altitude when the engine quits, but not as low as you might expect. Some are very fond of quoting the sharp rise in drag with higher speed, but an often-missed factor is the improvement in prop efficiency that also takes place. The real result is that the actual climb rate on a Bonanza will suffer very little.

The angle of climb gradient drops, of course, and it is possible for this to become a terrain clearance issue. Power reductions after takeoff have many considerations and variations, so it's a little hard to generalize. In all cases, use full takeoff power until the "flight situation" has "stabilized. In general, though, the gear should probably be up, the airspeed stabilized, some altitude beneath the wings, and the workload of takeoff should have abated somewhat.

On a low-IFR departure, perhaps you've turned to your initial departure heading and broken out on top of the low stratus deck. That's the time to set whatever lesser power the limitations section of the POH calls for. Some go further, with an even lower setting for "Climb. Many of our flat engines have no such limits, and are rated for full takeoff power "essentially forever.

With normally-aspirated flat engines, the increasing altitude we normally see automatically reduces the power within a couple of minutes, so it is almost silly to retard the throttle, then keep adding it back within minutes. There is a fast-growing major problem, however, and that is noise. A primary reason airports are closing by the dozen is noise at takeoff power, or more correctly, noise at takeoff RPM.

It is irritating , sometimes even to people who love airplanes! In Seattle, where I live, there is a constant procession of floatplanes overhead at 1,' to 3,', and many of these pilots and operators don't have this picture, because they're boring holes in the sky on sightseeing and training flights at 2, RPM or more, engines just screaming. I can only imagine the effect on people who don't like airplanes at all, or those who feel endangered by them.

For this reason, I suggest pulling off a couple hundred RPM as soon as possible after liftoff, no matter what the book says. Since Beech had to do certification testing for this, we know what the HP is. I usually do that as soon as the gear is up. At the risk of being accused of beating that poor dead horse again, please , please do NOT reduce the MP to 25" after takeoff or for climb, as has so long been the accepted practice on the flat engines!

You are not doing your engine any favors, and you may be hurting it. You can't go wrong doing this. There are several things you can do. The most effective one is to lower the nose and increase airspeed. Open the cowl flaps if they're not already open. If you're already full rich, this might be a good time to turn on the boost pump to "LOW" if available or "HIGH" to increase the fuel flow.

With the boost running, you may get too much fuel, and the cure for this is to lean a little.

John deakin manifold pressure switch

All of these will reduce climb performance, but unless you're about to hit something, it always makes sense to take the "hit" on climb rate in order to keep the engine nice and cool. There is mounting evidence that factory limits on CHT are much too high. In any event, try to keep the time above such temperatures at a minimum. The question is not whether to lean for climb, but when to start the leaning.

Many POHs will state pretty strongly that no leaning at any power setting be done below some fixed altitude, often 5, feet, and then in "cruise" only. This is patently absurd, but some people carry that to ridiculous lengths, even saying that it applies on the ground, for taxi operations! I suspect stuff like this comes from a quick meeting with a non-flying lawyer present, who insists that the POH must be written for the lowest common denominator among pilots, the utter moron.

Various suggestions get kicked around, and finally someone observes, "Well, you won't hurt the engine, or reduce safety with full rich below 5, feet, and you won't hurt the engine, or reduce safety, by leaning above 5, feet. That's easy, we'll just put in one line saying 'Lean only in cruising flight above 5, feet. The whole mixture discussion is cut to one simple, clear line, over which the manufacturer will never get sued.

Even GAMI is conservative about this subject, as misuse of the mixture control can indeed ruin an expensive engine, and I suppose they could be sued. Be forewarned, my defense in court will be, "You did what? You took advice from some nut on the Internet? Can I reduce "leaning in the climb" to one simple sentence? Sure, it's easy! Like the book says, "Lean only in cruising flight above 5, feet.

But even this can get you in trouble! Take the case where you're climbing out, ROP or even full rich. Hot day, hot fuel, and the engine-driven fuel pump is hot enough to heat the fuel even more. Bubbles begin to form, and these move through the lines, to the combustion chambers. The fuel flow sensor won't detect the bubbles, so you show the same old fuel flow, but with all the air bubbles, it's actually a very lean mixture.

This can drive one or more CHTs up very quickly. If you have a cylinder that runs hot already as most 2 jugs do on Bonanzas , this may be just enough to drive that jug into detonation. Nice to have the settable warnings on an engine monitor, as the JPI has. To operate lean-of-peak LOP during climbs, or in cruise below 5, feet, you need at least all of the following:.

If you lean aggressively during climbs at the lower altitudes without all those factors present, you're playing with fire.