and
MORE!
but you can't say
that about a teenaged boy's car engine can you?
Then there's THE PILOT
who religiously changes his oil at say 50 hours. That's all
well and good, but say it took him eight months to put that time
on the engine. Oil not only contains a life-limit of the amount
of operating hours for effectiveness, it also contains an
operation life-limit of time! Oil viscosity can break down in
several ways not the least of which are violated by time and
operation techniques. If you've got one of those airplanes with
the completely misunderstood "low time"; say 2,000 hours vs. the
industry average of 4,000 hours, sure you have a low or lower
time bird, but is that always the desirable thing in choosing a
used aircraft to purchase? See my article
.
Low time engines and airframes can be a good and a bad
thing and it all depends on how that engine and airframe were
cared for, especially the low time hanger queen that maybe sees
an oil change only once or twice per year if that which
translates that when the engine is under operation, it is NOT
FULLY PROTECTED by your engine's life-blood.........the OIL! So
if you don't fly your prized possession often enough to justify
timely oil changes, you must at least change the oil at proper
time intervals even if it hadn't been flown since the last oil
change. Oil filters are not so much affected by time, so if you
have low running time on your oil, but over-time since it was
changed date wise; you should change your oil, but you may
continue operating your oil filter up to 100 hours although most
pro's I've spoken to maintain that engine oil and filter should
be changed at 50 hours, so you can in effect change your filter
at 50 hours, but you should keep in mind that the oil itself has
a timed life limit. Are we beginning to see a trend take shape
here? Engines are very expensive. Oil is cheap......do the math!
Descent errors: What is better for the engine; climb or descent? When you're in the take-off/climb mode, assuming that all things are equal and you've taken physical care of your engine by starting it properly, keeping the fluids changed at recommended intervals; then probably the climb is better for that engine, especially after 20 years of flying with pilot/customers watching their flying habits. The reason I state this is having watched the descent portion of flight as operated by the average pilot. There is not much to do in the climb other than to monitor temperatures and pressures and apply correct leaning techniques on climb out. Normally aspirated engines as a rule should not be leaned until you reach altitudes of about 5,000' and beyond. Those engines are usually not capable of producing more than 75% power from 5,000' and up, so it is okay to lean at 75% and below. However turbo charged engines are capable of creating 100% power above 5,000', so they should not be leaned until you get to altitude or reduce power at or below 75% power (check your operator's manual as there are some variances to consider in certain models). The bottom line here is that the average pilot that I fly with does okay in the climb portion of flight overall, but remember that some mistakes can be made even in the climb. It is the DESCENT ERRORS that I wish to focus upon because therein lays the most mistakes that can adversely affect your engine. I don't care if I happen to be flying with an airline captain or even a light plane flight instructor, I see the same errors being repeated time and again. Consider that aircraft are different to operate than your car, enough so as to affect the longevity and reliability of that engine. Your car engine has been designed to put up with a certain amount of abuse, but we have to consider that the automobile engine is not subject to the rigors of flight. Most automobile engines are not designed to operate at full power for any length of time but our aircraft engines are and consideration should also be given to the aircraft engine because of the operating atmosphere that is subject to change moment by moment in flight. So what is this OPERATIONS ERROR that is so often repeated in descent? It is the way that power is reduced not taking into consideration the over-cooling that engine can be subject to and what I find most often is the habit of the pilot that dates back to his Cessna 150 learning days. He simply pulls the throttle back for descent and that's it! If you fly a Mooney; you know how quickly speeds can build up in descent in that super slick airframe, so add that to the fact that the power has been pulled way back to help keep speeds in check. I have often seen pilots keep doing that all the way down from high altitudes and I cringe for that engine. Here's a Riddle: What single item in flight is VERY GOOD and VERY BAD for your engine? The answer is HEAT. Heat is BAD for your engine on climb out and cruise, at least of the excessive variety. HEAT is GOOD for your engine on descent, so you naturally ask; well then how do I keep my engine's heat up upon descent? Is that really possible? The answer is a resounding YES! But before we suggest this simple technique to keeping engines (specifically when equipped with constant speed propellers), let me give you an example that remains within my memory. Back in the early 70's while flying a Piper Cherokee to somewhere I overheard a frightened sounding low time pilot call departure control to tell him that his (also a Cherokee) engine was overheating and asked if he should return to the airport (Van Nuys). Sensing that he was a low timer, the controller suggested that that would be a good idea, so the frightened pilot flying over the wall to wall homes near Van Nuys elected to begin a descent back to Van Nuys only to be followed by his declaration that all is well now and he had decided to continue his flight including changing his descent back to the climbing mode. Not more than five minutes passed before that same pilot told the controller that he does indeed need to return to VNY because his engine started to overheat once again. What's wrong with that picture? Even I, a low time pilot at the time knew what was up, yet it never seemed to cross that pilot's mind; and that was; of course, if an engine is going to overheat, it will most likely happen on climb out, but once placed in the descent mode which is throttled back with nose down, that will cool any overheating and normal operating engine down! He mistakenly thought that the problem had corrected itself and stupidly began his climb out once again. This guy should have taken Auto Shop 101 in high school! But let's not forget that we are talking about "normal" descents and in an airplane equipped with a constant speed propeller as most Mooneys for instance possess. So where we're going here is for you to consider doing more on the descent than simply reducing power. We're talking about how to effectively reduce power but keep the temperatures at a reasonable reduced or reducing rate and you do that with your PROPELLER CONTROL in conjunction with your throttle. I dunno, I've heard that in many turbo charged airplanes to not reduce MP (manifold pressure) to more than about 2" MP per few minutes, and while that may have some benefit to keep "shock cooling" in check, it's a bit unrealistic if you ask me. A reduction of 2" MP coupled with descending the aircraft doesn't do much for the speeds that will increase during the descent, so what to do? UNWIND THE PROP CONTROL as well! Here's an experiment I'd like you to perform the next time you are flying around: Reduce your power as you usually do and take note of the drop in cylinder and oil temperatures after enough time as been allowed for temps to change. After you do that, fly back on up to the altitude you were at originally and set her up for cruise as you would normally do and then allow the temperatures to stabilize with enough time. Now this time go ahead and reduce power with the throttle as usual, but subtract about 5" MP from your usual setting for descent and then unwind your prop control to a more coarse pitch and as you do that, watch to see of the MP increases all by itself. You will find that it does indeed do that, so what does that translate to? More heat for the engine at a time when your engine is craving heat, and you are craving a higher descent rate without taking a chance on over-speeding your airframe; for example, let's say that we're cruising at 8,000' MSL, and you need to start downward and don't have all the time in the world to accomplish that task. Say you're flying an airplane with the Lycoming O or IO-360 such as found in D, C, B, F, and J Mooney models or any other brand for that matter. A check within your operator's manual will show legitimate power settings of say: 19.5 squared. That number at least in many Mooneys is a legitimate power setting for even cruise should you want to keep fuel economy in mind, but here we're speaking of the descent of a non turbo charged Lycoming engine with constant speed propeller, without violating red or yellow markings on the RPM gage where some Mooneys and others for instance are restricted from RPM operations between 2000 and 2350 RPM. (Stay out of all red and yellow zones for any length of time due to vibratory harmonization problems those speeds could create for the propeller blades). A long time ago, probably the greatest Mooney Guru, Charlie Dugosh (Dugosh Aviation) told me that no matter the speed downward, on normally aspirated engines you can reduce power down to around 18" MP and never shock cool that engine, so let's do Charlie one better and reduce our MP down to around 16" but immediately follow that by reducing your prop speed to around 18-19.5" as well. What I want you to take note of is while you are reducing your RPM is watch the manifold pressure increase to about 19-19.5". Now you'd be set up for a descent at a reasonable airspeed, but you may ask; why does the MP raise when you "unwind" the propeller? It is the demand that is placed upon your available horse power to increase your MP without touching your throttle in doing so and the reason is your propeller when being set a a coarser angle relative to the wind takes more power to push it through the sky than when more finely set where the blades do not create much resistance to the air around it, thus your engine helps compensate that by automatically adding MP when your RPM is decreased. So? So, a harder working engine is a WARMER running engine as it is the power that increases heat in the engine, so you can effect reduce "power" while continuing to create heat while slowing the bird down before and/or during the descent. It's kind of like downshifting your car. The downshift can slow you down but increases horse power output which in turn creates heat. TURBO CHARGED engines are really no different on descent. My personal practice is to lower the cruise RPM about 6" immediately followed by reducing RPM. Now it is usual that most power settings in at turbo are a bit different in that you normally fly cruise speeds at an "OVER-SQUARED" setting meaning that your MP is usually set at a higher value than is your RPM i.e. 33" MP and 2400 RPM. Much the same as the turbo's normally aspirated engine, both have an increase in MP when the RPM is reduced. So, on both type engines is it a good idea to practice with your power settings as suggested above during descent and in turn you can be more assured of reaching that "all important" TBO without having had to spend much $$$ in between overhauls, but that is just a part of proper engine operation that leads to engine longevity. However; I think that we have established at least thus far that more than who did your last overhaul, WHO IS THE OPERATOR of that engine and his methodology, and can he or you the next owner expect to reach and possibly exceed TBO? Wow, that was a long paragraph!
Improper Leaning Techniques: Again, we blame (or reward) the pilot here. There' seems to be as many questions about proper leaning as we do the "when should I overhaul my engine" question, but these two things can also go HAND-IN-HAND toward ENGINE LONGEVITY. "Oh yeah baby, I don't lean my engine much because too much fuel is better than too little fuel".......... An AVIATOR should be more concerned with PROPER ENGINE OPERATION than by taking the stand that SOME IS GOOD, so more must be MORE-GOODER. Here are more things then to keep in mind that help ENGINE LONGEVITY.
a. When do I start my leaning procedure? The answer is when you shut your engine down and by that I mean that you kill your engine with the mixture correct? So it is a good practice to not push that mixture in until you restart your engine. This is especially important on Lycoming Fuel Injected engines because restarting most engines when run previously that day require the mixture to have not been enrichened at all since shut down because there is usually fuel pressure in the system even after engine shut down, so you will want to keep that excess fuel away from your fuel metering system. I know that this point does not have much to do with engine longevity as much as it has to do with easier engine starting, your leaning procedures begin with doing this aright.
b. If you have a normally aspirated engine you should lean immediately upon startup. Here's an experiment for you. Start your engine and set the idle at say 900 RPM. Now begin to lean it and keep doing that until you see a rise in RPM before it drops again. It is at the peak RPM (probably 100 rpm increase) that your engine is happiest. Not ground leaning to peak RPM but doing some leaning just slows down the cancerous result that is ever building in your engine, and that is CARBON deposits. I knew this one pilot that had an E model Mooney and he was proud to say that at 2200 hours SMOH, his compressions are a solid 80 over 80! Wow? No. His engine is probably near coming apart and certainly running inefficiently at best and he was fooled thinking that compressions are a gage of engine condition when they are not. This guy's engine was so full of carbon that carbon formed on areas of tolerances that normally allow the compressed air to exit and some compressed air has to exit or you'll have problems. That's why the overhaul to "new tolerances" is a better overhaul than just overhauling to "service limits" which can in itself also help define ENGINE LONGEVITY. Anyhow, let's continue on with proper leaning techniques to see if you practice this to help answer your own question about engine life. Never lean an engine that is running at full power until you reduce power to suggested cruise power settings which is usually 75% or below. Some guys don't lean their planes at all at low altitudes and that is wrong. Whatever the altitude, if you are at 75% or below, lean that sucker! But how? Lycoming 4 bangers are a forgiving engine to an extent, but you can run them lean of peak all day long, even leaning to rough and it normally will not hurt that engine so they say. Flying is balancing performance with economy and you have the say-so as to which one you want; power or economy. That's up to you and subject for another article, so let's go by the best mixture of power and performance. There are several ways to lean an engine starting from the age-old lean until rough then richen it about 1/4" and the engine is happy. Is it? Yes. Is it more efficient that way? No, only because it takes the real engine operator's control from him in effect taking the easiest way out whereby the real engine operator wants the precision control over his engine, so he's apt to be more technical in his approach. Armed with that, he would want to have at least an EGT (exhaust gas temperature) gage to go by. He will get used to the approximate EGT needle position and start out a bit richer than that. As with any engine control, adjust it slowly but deliberately. Once the EGT needle passes that position, begin to slow down on turning or pulling the mixture knob until the EGT needle peaks to the highest temperature that it can reach, and then reverse the mixture to the richer position until you pick up around 50 degrees F. That is known as: 50 ROP or rich of peak which is an excellent compromise between economy and speed. Obviously if you want more speed, run it 100 degrees F rich of peak, or up to 100 LOP (lean of peak) for better economy. On a side note; if you lean your engine past peak EGT, you will see the temperatures start to cool down as well, so the old adage to keep your engine cool is to pump a richer fuel mixture through it. Don't necessarily buy into that falsehood.
c. Turbo charged engines are not much different to lean but don't really operate all that happy LOP unless you have a Turbo Mooney 231 engine that has had the Gami fuel injector retrofit at which time you are now encouraged to run it LOP and save nearly 3 GPH in that engine/airframe which suffered a bit at the standard induction system. Variables continue to continue...... However, many turbo 231's have fuel flow meters and once you know your Turbo airplane well enough you can do as I do and that is to lean to fuel flow, at least initially. A standard 231 for instance will normally burn 12.7 GPH at a reasonable cruise setting of around 75%. Once I lean to fuel flow and have time to tweak stuff, I will then go back to the EGT or TIT (turbine inlet temperature) to do my "fine tuning" of the fuel mixture.
d. Descents are no different. You should adjust your mixture on the way down for three reasons. Firstly, if you are at higher altitudes and descending, your engine will eventually lean itself to harm and even engine fuel starvation and may quit on descent at some point, and secondly, fuel economy is dictated by your overall fuel economy and if you don't properly adjust the mixture on descent but richen it at altitude like I see some do (in case they forget later); and thirdly, consider the carbon engine cancer I was speaking of earlier and will continue on that subject later on in this article. While on descent you may not have as much time to tweak as you do in level flight, it is a good practice to keep your engine fuel/air mixture in mind on the way down by keeping any eye on your EGT and doing what you have to do when you have time to keep it at the lean temps it was in cruise but because of the variable of power settings, get used to interpolating that by practicing different power settings when you're just up boring sky holes and when properly leaned you can memorize the approximate EGT settings at differing power settings and then apply those approximately to your current descent settings, or at least rewind your mixture some with each 2,000' of altitude you lose. The GUMP check; gas, undercarriage, mixture, and prop for just prior to landing has the "M" in the word for a reason. It is best to operate your engine below 75% power all of the time, so even in the pattern prior to your first GUMP check you'll have been in a leaned position and of course you richen the mixture for landing just in case you need your 100% power to go around, but once on the ground, I re-lean the mixture for taxi (non turbo's).
MORE ENGINE LONGEVITY CHECKS start at the birth of that engine whether new or overhauled. I would dare say that your engine's weakest part are the cylinders. If any engine is improperly broken in, then the rings may never seat as they were supposed to causing a higher oil consumption and less engine power because your compressions are not as high as they should be, therefore loosing combustion power past the piston rings instead of directly to the crankshaft where the horsepower is converted into movement. I don't know how daring you are but here is what I do with a new engine: After the installing mechanic runs the engine briefly to check for obvious oil and fuel leaks, I take over by checking how long the line is for takeoff, etc. and only go when I know that I'll be number 1 for departure which is relatively easy to do at smaller airports. I'll start up the engine and begin an immediate taxi to the active and while I'm taxiing I will ride my brakes and run the engine up to mag check speed and quickly do my run up on the move so that when I am at the runway I can just go, so on the boost pumps come and off I go at full throttle monitoring pressures and temperatures for a no-go indication. Once cleared I'm off and I keep full throttle mixture rich and climb up to around 6,000'. I will not touch the power settings at all except the mixture which I will lean as usual and then fly around the airport keeping it within gliding distance at all times just in case because if an engine is going to blow, it usually does so right after overhaul when something wasn't done right during the overhauling process. I will fly up to an hour like that before slowly descending at the high power setting until it is time to slow down for landing. Then I taxi in to the mechanic's shop and we check everything including compressions. It is a good idea to check compressions ever ten hours or so until you reach around 50 hours. At that point your mechanic will be able to discern if the rings and cylinders have broken in properly and once that happens, he can change your break-in oil to regular AD (ashless dispersant) oil. Your engine is now properly broken in and new enough to begin the proper operation of that engine so as to get the most life out of it that you can, and here are some important items to consider doing for your engine throughout life:
a. Change your oil at proper interval's as discussed earlier.
b. Keep your spark plugs in top condition and that is something you can do at each oil change. First off purchase a small container of spark plug anti ceasing compound at any auto parts store. It comes with a nail brush type thing. Your lower engine spark plugs take the worse beating because carbon and other impurities are constantly falling onto the plug's electrodes, so you will want to reverse plugs top to bottom and bottom to top. It is a good idea to clean each plug before you reuse it so if you have compressed air available you can buy for cheap a spark plug sand blaster/cleaner, but remember that you need to keep straight which was a top plug and which was a bottom. They do sell a spark plug tray that numbers them, but if you don't have that, place a piece of tape or nail polish on the tops ones to identify them later when you want to reverse them. Before you install each plug, put some anti cease compound on the first two threads being careful not to get any on the electrode, and it will be much easier to remove that plug next time, and you don't risk doing thread damage to the plug or the cylinder. Be sure to torque the plugs and wires correctly. Have you mechanic show you how if you do this yourself.
c. See that none of your engine wires are chaffing. Nylon tie wraps are your greatest friend here.
d. Check your mags and other accessories for mounting tightness and do that regularly.
e. Don't let oil build up in your engine compartment. keep the engine clean.
f. Check your engine mounts for sagging.
g. Check your oil and fuel screens at least at every annual or 100 hours. If you don't have an oil filter on your engine, check your oil screen at least every other oil change which would be at 25 hours per change if you don't have a filter, and if not, get it converted.
h. Check your engine baffling. This is critical in order to have your engine run its coolest.
i. Have your RPM gage or TACH checked for accuracy on occasion. Some of the older mechanical tachs have been off as much as 250 rpm or even more, so you may be flying in the redline area of prop RPM's and don't even know it, so it is a good thing to check that on occasion. One guy was proud that at 25 squared, he was burning about 2 gph less than advertised for his model, but he complained his plane was a bit slow. His tach was over 200 RPM off!
j. Do your mags when called for. You should at least have them checked each 500 hours or whatever is mandated for your model mags.
k. do an occasional oil analysis. It's cheap enough insurance that goes beyond just cutting your filter open and checking it for metal. BTW, a moderately carboned up engine will show some black carbon inside the filter.
l. Find and use any approved additive for your engine that serves at least the purpose of removing engine carbon. Remember, we are still using leaded gas in our planes and that helps lead to carbon buildup as well as improper leaning does, so remember carbon is your engine's enemy.
I haven't found an approved aircraft de-carbonater that works as well as Marvel's Mystery Oil does for other air cooled engines such as on motorcycles, etc. The problem is that no one ever wanted to spend the money the FAA requires in order to make it approved for aircraft, but I have known many pilots that swear by it and use it nonetheless, but I cannot recommend that for obvious reasons. However I can tell you the benefits of running it motorcycle engines. I have ridden motorcycles on and off since I was 13 or 14, and Marvel's has been an important part of engine longevity for several reasons. While Marvel's can blow up just like gasoline can, I add the ratio of about 4 oz. per ten gallons of fuel. In the fuel Marvel's having a lubricating quality to it helps keep the rubber parts of the fuel system lubricated where fuel alone has no lubrication value. Engines that suffer valve guide problems like the Lycoming does to an extent, Marvel's would keep the valve guides lubricated and does not allow the push rods to stick as they sometimes do. Perhaps you hear your plane makes popping sounds after landing on taxi. That is your push rods hanging up inside the engine until the cam come around to pop them back into position, so it's too bad that product is not FAA legal or I would use it for that reason alone. Those of you who have any kind of sealer in your fuel tanks benefit from lubrication as well. Fuel is dry and it dries out everything it comes in contact with, even your hands. The highest benefit comes from using Marvel's in the fuel system of a motorcycle is that it soaks the carbon buildups inside the engine and then blows the carbon harmlessly out of the breather, and when used continually it will eventually remove all carbon which is a good thing in younger healthy engines than an old tired one because at times carbon tends to hold it all together. :o) Another area of benefit is inside the engine. I use a quart of Marvel's for every oil change in my MC and expect that to burn out quicker being a lower viscosity as it is, but it leaves a protective coating on the engine parts so that when heat from running caused all of your regular oil to fall off the engine parts and return to the oil sump, the Marvel's will stay on those parts and make engine starting a bit less traumatic on the engine, especially on cold starts. It also helps keep engine seals more pliable. I do wish someone would pay the bux so that we could use this all benefit no drawback and cheap product in our aircraft engines. However, you should speak to your mechanic to find if there is some FAA approved product that would work as well as Marvel's would in your engine.
What have we discovered thus far regarding engine longevity? We learned that the operator is more important than who overhauled the engine last. We learned that simple but necessary preventative maintenance can be real important to the life of the engine, and we learned that TBO is just a recommended time for overhaul and why. If you want to be an "average" engine operator, you'll probably do okay and make it to TBO. If not, don't expect your engine to make TBO....But zef! Can I exceed TBO safely if I don't operate my airplane Part 135? Absolutely! If you take proper charge and care of your engine and its operation, I personally have exceeded TBO by up to 20% and when I had the engine done, they asked me why the engine was like brand new inside and the pistons were like mirrors.... I dunno... maybe it had something to do with operation practices and the right kind of additive.
What about what the engine manufacturer says about time alone and not hours for TBO? Well they're right to an extent. Some engines can be low hours but flow little to reach TBO in hours of use as opposed to time in service. Is that just the engine company's lawyer talking? Not always. ANOTHER ENEMY OF YOUR ENGINE IS WATER. Water?! Aren't these air cooled engines mostly? Yep, but your engine temperatures can and do change drastically in use and when the air is right, the engine develops water contamination through the affect of condensation. Every engine has some water in it until you run that engine up to a minimum of 180 degrees F for at least 20 minutes, so if your engine and airplane is sitting a lot, don't feel sorry for it and run it up on the ramp. Chances are you're just circulating water inside that engine that results in rusting parts. Your mechanic can check for a lot of the problem by doing what is called a Bore Scope check. Rust will start in on your cylinder walls and/or rings and he can discern that with his Bore Scope. Crankshafts have failed before and pilots have watched as their propeller simply flies away and this is normally due to internal engine rust (when not due to factory screw-ups in production) which is rare but has existed from time to time. However I have seen some engines checked and even dismantled somewhat to check for corrosion and some of those engines were decades old, yet checked out just fine. Also important to keep in mind are the improvements brought on by the FAA through service instructions and AD's that are to be complied with at the next overhaul, so it would be a good thing to check with your mechanic or engine manufacturer as to what improvements and why are available since your engine was last overhauled.
The email that was the straw that broke the camel regarding TBO and beyond came just this past week and after answering this complicated question in as few words as possible led me to finally write this article. Below is the email and my reply, just for kix:
Hello Mr. Zephro. I'd like to complement you on your very informative website. Would you mind answering one question? I own a 1984 201 with 2695 TTAE and 695 SFOH. The overhaul was done in 1992. The engine is running superb and strong with normal oil consumption with compressions 75 and above across all cylinders. I had the engine borescoped recently with no evidence of corrosion. Oil analyses are also good. My question is how do I decide when to overhaul. It's well over the calendar Lycoming recommendation of 12 years but well under TBO. And it's running very well. Any input would be very much appreciated. Also do you have a good way to restore the interior royalite plastics? Thank you in advance for your kind response.
Peter T. KMy response:
Hi Peter,
TBO is an average taken of engines that have been used in every type of service including the all punishing student pilots. Add to that a team of lawyers and you begin to comprehend that like people; no two engines are alike. If it were mine and there is no discernable rust inside the engine, I would run it on hours rather than time. However, I know how to take care of an engine, so not knowing your habits and those who flew the bird before you, how do they cold start the engine, do they run it on the ground only?; that is the questionable portion of the quotient. My original Mooney, the E model was beyond TBO and I didn't know it because the man I bought it from said the TBO was 1800 (at the time) when indeed this engine's actual TBO was 1400.
So when we finally did the engine, it had around 1800 since new in 1965, and this was in 1990. When they pulled the engine apart, they said it looked like it was new inside. The reason was that the original owner and I used the same additive of which had you been a Mooneyland customer, I would have taught you about, but I must consider liability. And then I took my '78 201 to ten percent past TBO on a 15year old engine, and that engine shop reported that the insides were like in and within new tolerance still. Again I used the same additive.
The bottom line is that whence you exceed the manufacturer's suggested TBO times, you are on your own, but of course you were on your own within the TBO time as well. Your engine will not magically quit at 2,000 hours or 15 years. Having a good mechanic who knows engines well should be of value to you as you fly. He should be aware of any important engine upgrades since yours was done or new. You can always pull a cylinder and look right into the engine. To me, the fuel system is the most important part of that engine's proper operation so you should inquire about things such as your fuel injector servo, your muffler, and the weakest point of that engine; the camshaft, the valve guides; (that's where the additive comes in) etc. These are things that can take out an otherwise good engine. If I were to give you my recommendation to continue on with your engine, or to suggest a non FAA approved additive, I could be subjecting myself to liability as a professional in aviation, and you can understand that you're not one of my customers in a business that I am in to sell aircraft and technically support my customers, so I can't put myself in jeopardy by suggesting you keep flying it. Just know that compression has little to do with the overall health of an engine. It could be so full of carbon that the compressions are high because carbon is blocking the pressure escapes.
Meanwhile, thank you for the compliment on my website. If you think that the site as well as this personal response to your inquiry was at all valuable, feel free to donate to our site to encourage the articles to keep coming.
Thanks,
Rich Zephro
zef
You know dats right!
NAVIGATION
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