Popular Content

Showing content with the highest reputation since 09/06/2012 in Blog Entries

  1. 4 points
    First a note of explanation: a manifold pressure gague is an absolute pressure gague. What this means is that it is an uncorrected barometer connected to your intake manifold so with the engine not running it indicates uncorrected field pressure. Those among us living at or near sea level can look at the gague and expect it to read the same as the Kolsman window when the altimeter is set to field elevation. Those of us living at significant altitudes above sea level look at the gague and ponder if what we are seeing is right. My field is at 2,400' and my gague reads 27.4" with the local altimeter (corrected barometer) at 29.85", Perhaps a flight to a sea level field might resolve any insecurity but there is another way. The website http://www.csgnetwork.com/barcorrecthcalc.html has a handy calculator. You just enter your field elevation and current altimeter setting in the top column and read the uncorrected mercury column and correction factor at the bottom. For my field elevation the correction turned out to be 2.5" which corresponds to 29.8" within .05" of where it should be. Now I have confidence in the instrument without having to go to sea level to check it. This same calculator can give you the maximum theoretical full throttle manifold pressure for any cruise altitude and within 1/4" the power you would achieve. A bit helpful when trying to calculate crise performance for altitudes that fall between the charts in the POH. As an Airframe/Powerplant mechanic with extensive experience in both large jet transport and general aviation aircraft as well as avionics I will be writing other blogs trying to take some of the mystery out of small aircraft systems. If anyone has questions on or suguestions for articles, please comment.
  2. 3 points
    To a lot of Mooney owners a fuel leak can seem quite intimidating especially to those owners who do not hold an A&P rating. I must admit that I was intimidated at first. A small amount of leak (a seep) is permitted per the Mooney service manual as long as it is not into an unvented area so top of wing or gear bay is permissable but cabin, outboard wing area or leading edge are not. My seep was into the leading edge and over 4 months drained the left tank dry; not enough to leave a stain on the ground but enouch to stain the stain the bottom of the wing adjacent to the leading edge drain hole. This meant the leak had to be at the bottom inboard corner and the blue fuel dye stains confirmed. As it turned out the hardest part of the job was getting the tank inspection cover open without damaging the wing. Scraping the old sealant was a bit tedious but really only took a couple of hours. Using a A-2 gave a lot of work time on a cool day and working with a brush which I had trimmed the bristles to 1/2". I sealed way beyond the leak area to make sure that no fuel could work it's way under the repair.of course I cleaned the area and roughed the surface of the factory sealant. To close the tank I used an B-2 wich is not what I would reccomend because it is way to slow, a B-1/2 would be much better. There is an A/D to inspect the stringer and rib drains to make sure you have not clogged them before you close the tank. I allowed a whole week to cure before filling the tank for a leak check and another week before checking for leakage. I am absolutely 100% leak free for $80 worth of supplies. For those among you who are not certified mechanics there are mechanics who are willing to work with owner assistance. I know of one on my home field who supervised a non mechanic owner in replacing an entire cylinder set (top overhaul). There isn't much room inside the tank for two pairs of hands but most mechanics would gladly defer the prep work to someone else.
  3. 2 points
    Hi! I hope this will help other Bravo owners who struggle to run the TIO-540-AF1B at Peak or LOP TIT. But first, in full disclosure I am not an A&P and this is not advice. I am simply illustrating my experience with this engine, and it or may not apply to you. Always follow the POH when you are not sure that your deviation from that document is in your best interest. I am a lean of peak fan, always have been. It comes back from my days of working on non-aircraft internal combustion engines and proving that an engine run LOP operates cooler, cleaner and lasts longer than a similar engine run ROP. I have taken the Advanced Pilots Seminar course on advanced engine management http://www.advancedpilot.com and had numerous discussions with Lycoming engineers, the folks at GAMI and engine builders, and I have used this knowledge to come to a few conclusions about this engine that I would like to share. I am not poking the sleeping “ROP vs LOP” dog. :-) and I realize that Lycoming - in some instances but not all - does not recommend operating LOP. I also believe that if they could, they would revise that language to say: If you have a good engine monitor, tuned injectors, and a knowledge of how your engine operates, you should run LOP whenever your heart desires - except on take off. My opinion is that Mooney, when they introduced the TLS, continued their fine mission to make the fastest commercial SE piston airplane. To do this, they needed a lot of power -and- in a weight package that would not cause the flight envelope of the long body to get too forward on the CG, the TIO-540 was the answer. Bravo owners know that the airplane is already pushed forward CG and many have Charlie weight for aft ballast installed (which lowers the already skinny useful load). The TIO-540 is a complex high performance engine and should not be grouped with most other ground boosted engines for performance discussions, The reasons for this, IMHO, are due in part to two things: 1) a complicated (but effective) turbocharging controller system, and 2) the requirement that the engine runs at very high percentage of power levels to make book speeds. I did a post a few weeks ago on the Bravo’s power percentage here. Because this engine is normally operated at greater than 80% power during cruise by most people, this engine is very working hard and making a lot of heat for a lot of the time. It is also doing so with rather loose factory tolerances on the precision of fuel flow to the cylinders which makes it extremely difficult to run this engine in an wide and efficient range of power settings. The POH states only two settings: 1) ROP TIT by at least 125dF for “best power"; and 2) Peak TIT as long it’s below 1750dF (1650dF at high altitudes) for “best economy" - the latter is sometimes impossible to achieve with this engine at higher power levels (30” MAP and above) because of poor fuel distribution which causes engine roughness. When near peak TIT (or EGT) the roughness is normally due to some cylinders running leaner than others. The leaner cylinders produce less power than do the richer cylinders which give you the impression that there is something wrong because you feel that power imbalance as roughness. (Note: that slight roughness is not a bad thing, your engine won’t fly apart, it really doesn’t care, only you do.) Spark plugs play a key role in this too - more on that in a bit. Here’s the rub... Because most of the TIO-540-AF1Bs have unequal cylinder fuel distribution, when Bravo owners try to run the engine per the Sun Visor chart at Best Economy (Peak TIT) they may find an disconserting “roughness” and feel a slight loss of power. That combo causes some consternation, and when that happens, some operators I’ve spoken with will simply dial the Bravo’s red knob in just a little richer and go slightly rich of peak TIT just enough to cure the roughness. Thinking that they are now 'just fine’ they fly the engine at that setting - when in fact they are not “just fine." They are now operating the engine “slightly ROP TIT” at a mixture setting that causes the most cylinder head heat, the highest internal combustion pressures and at a place where the engine can easily begin to exhibit detonation. (See graph below, which was taken from the Lycoming Flyer publication) The Mooney POH does not say it is OK to run the engine “slightly” ROP TIT because both the factory and Lycoming know that is a very bad mixture setting. All of the experts I’ve spoken to agree that no internal combustion engine should be operated “slightly” (10-60dF) rich of peak. If you can’t make Peak TIT for whatever reason, better to just go greater than 80-100dF and accept the extra fuel costs and keep things in the engine cooler and happier. I have not found anyone who disagrees that sustained high heat weakens, fatigues and shortens the life of the metals used in engines, and that’s why we see all kinds of advice about keeping cylinder head temps below 400dF. The Bravo’s POH advises that you use a combination of gauges when setting power - TIT and CHT as the most prominent. The POH also says that the CHT redline for this engine is 500dF - which everyone (experts or not) agrees is simply ridicules. If you have an older Bravo, and especially one where a field AF1A to AF1B conversation was done, you may want to check to see on which cylinder the panel’s CHT temp probe is located. The AF1A probe was located on cylinder #5, and Mooney Service Instruction M20-101C states that it should be on cylinder #3 for the AF1B. Check yours, especially if you rely on the single panel CHT gauge, I’ve spoken to three Bravo owners where the CHT probe was still on #5 (mine was too). There is a big difference in the cooling between #3 and #5 - #3 being as much as 50dF hotter. That all said, in summary the TIO-540-AF1B is a hot running, high power, high performance engine, different from many others. In the M20M it is asked to operate at the top of its performance range in order to make POH (book) performance numbers, and us Mooney drivers like to go fast! Adjusting the mixture on this engine can be tricky due to engine’s generally unequal cylinder fuel distribution and, in many cases, the wrong type of spark plug being used. I wanted my Bravo to act like most other well-tuned and instrumented airplanes I’ve flown. While always keeping the cylinder head temps below 400dF, I want to be able to safely set the engine for maximum power when I want to go fast, and I want the ability to safely save fuel when fast doesn’t matter as much. I don’t want complicated instructions to do this, and I want to feel as if the engine is happy and smooth no matter what. Before I started this trek, I could not run my Bravo at Peak TIT at MAP higher then 29” without noticeable roughness and/or what I felt was unacceptable power loss. And there was no way this engine would run LOP. I would flow about 22 GPH of fuel in cruise at 100dF ROP TIT (on hot days I needed to to be richer to keep the CHTs below 400dF). Here’s what I did. I first ensured that magneto timing was correct. This is very important with high performance engines; you can often get away with inexact timing on lower power engines, but never on engines like the TIO-540. Mine were pretty close, but not exact - they are now. I had new Champion massive plugs installed about a hundred hours earlier, on inspection they looked okay and they passed the tester test. We gapped them at .016. I installed a new set of GAMI TurboInjectors. When I spoke with the factory rep John-Paul he cautioned me that this engine was a hard tune and that I should expect to have to work at, and that there might not be the success that others have with GAMIs on other engines. I love honesty - these guys at GAMI are true pros. The first set of injectors made a marked and clear difference. I was able to run at Peak TIT smoothly for the first time, but I was unable to run LOP without roughness. I did a GAMI lean spread test and found that my spread was about 1.4GPH, while better, it was not ideal. I contacted the factory and John-Paul immediately sent out two replacement injectors for a better match. After that a test flight or two it showed that I actually picked up about two knots at peak TIT and fuel flow was down a little. I could now get a little bit LOP with a GAMI spread of .9GPH. Also noticed CHT were generally cooler by about 20dF. This was due to the fact that the better fuel distribution was allowing all cylinders to run more equally, so at Peak TIT all cylinders were closer to their peak EGT. Fuel was saved for the same reason - unnecessary rich cylinders were now leaner for any given mixture setting. Because this engine seems finicky at different MAP/RPM settings, I decide to tune to a specific sweet-spot for the GAMI spread - I picked 29”/2400 for this as it is, according to the Lycoming power graphs, about 75% power on a standard day, at mid altitudes. This might have been the most important step I took in achieving success with this tune, on this engine to allow for good LOP performance. I sent the new GAMI lean test to John-Paul - not satisfied he sent me a single replacement for the one cylinder that was off a bit. (no charge for all of this and no questions asked). We installed that one injector and then did a test flight. The biggest change was that I could get more LOP without roughness, at 2400/29” I could get to about 20dF LOP. I would lose about 9 knots, but I was able to save almost 6 GPH of fuel. While I still couldn't get much past Peak TIT at higher power setting I was happy with the trade off; now I could achieve both fast and efficient settings. My GAMI lean spread was now a very comfortable .3GPH as you can see from the graph below. I thought that was all I needed to do but it wasn’t ... I have a Savvy Aviator account, I upload my JPI engine analyses data there, and I happily buy their yearly analysis service. I uploaded a flight and was looking at the graph and saw something on one of my lean spread tests that I could not understand. During a lean test, you should see all EGTs rise as you get leaner and leaner, then they should all peak (at slightly different times, that’s the fuel flow “spread”) and then they should drop off. On my test, there was a second peak? I submitted the flight for review at Savvy and Paul Kortopates wrote back and explained it, and as soon as I read his explanation I understood: He said "That second "peak" is actually what happens when the mixture goes lean enough to fire only one plug. You are seeing the same rise we would see if you switched off one of the magneto's so that there was only one plug firing- which is what we're seeing here. On one plug alone, combustion is slowed and therefore when the exhaust valve opens we are seeing more of the combustion event and the associated higher EGT because of it” That’s when we discussed the last step I needed to take to get this whole project right - new plugs - but specifically fine wire plugs. It seems as if the fine wire plugs work better than the massives in two instances 1) older wet and oily engines (not the case here) and; 2) in lean mixtures. They’re expensive, about $80 a shot, but they also are suppose to last hundreds of hours longer. After researching both Champion and Tempest, I opted for the Tempest Fine Wires and installed 12 of them. Paul was right on! From the moment I turned the key I could tell that something was different. The engine started better and ran smoother on the ground and in the air, and I am now able to run LOP at 32” MAP and below if I chose. My CHTs are generally 30dF cooler than when I started this project, and I am saving fuel at every power setting. Where I use to run 22GPH at 2400/32 ROP, I now run 20GPH with the same airspeed, and if I want to throttle back to 2400/29, I loose about 10 knots and run about 15GPH at about 20dF LOP. In all, I have about $2500 invested here, but in fuel savings alone that will pay back in short order and then keep paying back. The big benefit is that I have more power options now with the aircraft and my engine will be much cleaner with less carbon deposits on the heads, the values, the plugs and the exhaust system. My flight profiles are not religious LOP, and yours don’t have to be either to get a benefit from the cleaning and cooling aspects of running your engine with a proper mixture, which, for me includes LOP at times. Typically I will run lower power and LOP in tail winds of any speed, because why not? If I loose 10 knots true in LOP but I make up some or all with a tail wind, I’m saving 5-6GPH of fuel AND cleaning the engine as I go. Thanks for reading! I attached some pics - happy to try to answer any questions. Dave
  4. 1 point
    Day four was a huge success! We were a little late getting around and getting off the ground, but we were wheels up around noon. We were very curious and worried about some clouds we ended up flying right over and no issues with icing or getting stuck anywhere. We made our first fuel stop in KPBF, Pine Bluff Regional Airport Grider Field, for some incredibly cheap fuel and fun entertainment. After a quick trip into town for some diner food, we went back and enjoyed the culture that is incredibly accurate to the stereotype in Arkansas. The next thing I knew we were off to our final destination for the day, Huntsville Alabama International - Carl T Jones Field.
  5. 1 point
    Vapor lock comes in varying degrees, so a single technique to purge the fuel lines of “gas air” won’t necessarily work. I break it down by short heat soak (about 10 min or less) and long soak (about 30-60min) and yes, there is that charlie foxtrot area in the middle ~15-30 minutes where anything can happen. This discussion is for a fuel injected engine. During a short heat soak the likely culprit will be the upper fuel lines to the distribution device and the injector lines to the cylinders. Note, these fuel lines often sit atop the hot engine, and since heat rises, the relatively small volume of liquid fuel in these lines atomizes quickly and becomes a vapor (gas air). To fire a mixture off in the combustion chamber, there must be an atomized fuel mist suspended in the surrounding air. If the fuel is too atomized as in a vapor, the fuel density won’t be sufficient for firing, hence a hard start, actually due to a overly lean mixture. To clear a short soak, you need to pressurize the upper fuel lines with just enough fuel to push out the vapor, and not too much that you flood the intake ports. This is where most pilots get in trouble with hot starts; a hot engine needs far less fuel to start than a cold engine. The theory is to begin the starting sequence for a short heat soak with NO fuel flow and then ADD fuel slowly until it fires off. Most often, we do it backwards and that makes things exponentially worse. During a long heat soak, the entire fuel system comes in to play from the fuel tank feed lines to the fuel pumps, to the pump chamber, to the feeder lines, on up. It generally takes longer for these components to heat up and begin to vaporize after sitting than do the upper fuel lines. The clearing technique here is different than a short soak, as you want to (have to) push the vapor out of the pump circuit and that takes time; sometimes a lot of time. To clear a long soak, you need to purge the entire fuel circuit of vapor, not just the lines going to the injectors. In a long soak, there is a lack of liquid fuel in the pump circuit (because it got hot and vaporized away) ... and a fuel pump, while good at pumping a liquid, is very inefficient at pumping vapor. So you crank and crank and crank and nothing happens because nothing is happening - no fuel is flowing - because the fuel pump is essentially pumping air. In cases of a long soak, using just techniques that will effectively clear a short heat soak will do little to clear the pump circuit, causing a hard start. Knowing a little about why it’s hard to start a hot engine often makes it easier to find a solution. If this works for anyone send money; I have airplane payments to make and my wife and mistresses want jewelry. Short Soak: Throttle cracked to the point where it would need to be to have about 1000-1200RPM if the engine were running Boost pump OFF - (Do not use the boost pump or primer at all) Mixture Full Rich for about 5 seconds then Idle Cut Off Begin cranking the engine, wait a 2 seconds then slowly (over 5-10 seconds) move the mixture toward rich. Don’t exceed recommended cranking time. As soon as the engine starts, keep the mixture at about that point, adjust it and throttle for smooth operation. You should ALWAYS run the engine as lean as possible on the ground. Rationale: The throttle is cracked open so that when the engine fires, there is proper air flow for the fuel that is being slowly added by the mixture control. The Mixture is open fully for a few seconds first to allow any built up vapor pressure to purge out, then its closed; this gives liquid fuel a clear path down the lines. The mixture is kept closed until the cranking so that you have complete control of how much fuel to add to get the engine lit off - which likely will be different every time - this technique also significantly reduces the changes that you will flood the engine. There is NO boost pump used because the mechanical pump should be able to provide fuel at a rate that keeps excess fuel low, unless you have a hot soak condition... You will know if you have a hot soak event because the above technique will not work after two tries. Summary: There is liquid fuel available at the fuel pump but there is vapor in the injector lines. The vapor does not ignite easily and it blocks liquid fuel from flowing past the vapor area (vapor-lock) causing a hard to start condition. You have to relieve the pressure of the vapor and then slowly add liquid fuel to the lines and the injectors so that the mixture of fuel and air is correct for ignition in a hot cylinder. Long Soak: Throttle Closed Mixture Full Rich for about 5 seconds then Idle Cut Off (Be very sure it is fully at idle cut off) Boost pump on (or on low if two speed) for 30-60 seconds. (yes, a full half a minute to a minute) Boost pump OFF Throttle cracked to the point where it would need to be to have about 1000-1200RPM if the engine were running Begin cranking the engine, wait a 2 seconds then slowly (over 5-10 seconds) move the mixture toward rich. Don’t exceed recommended cranking time. As soon as the engine starts, keep the mixture at about that point, adjust it and throttle for smooth operation. You should ALWAYS run the engine as lean as possible on the ground. Rationale: The Mixture is open fully for a few seconds first to allow any built up vapor pressure to purge out, then its closed; this gives liquid fuel a clear path down the lines. You want to be very sure that the Mixture is fully at idle cutoff because we do not want any fuel to get past the metering circuit. Running the boost pump with the mixture closed will pressurize the fuel circuit and circulate some liquid fuel which will help cool things down and reduce additional vaporization. Excess vapor will be expelled through a vent port and the mechanical pump and the lines leading to the metering circuit will become fresh with cooler fuel. This takes time, and you have no worry of flooding the engine because the mixture is at idle cutoff. You finish by following the same procedure as a short soak. Summary: The mechanical fuel pump has to have the engine cranking to do its job. It would take too long and be too hard on the starter to use this pump to purge vapor. (Hence why I’ve seen pilots cranking the engine for absurdly and dangerous amounts of time). The electric pump is parallel* with the mechanical pump and has the ability to run quickly and more efficiently to do the job of purging the vapor, but its not an easy job - it takes a lot of time therefore you need to run the pump for at least 30-60 seconds. Once the vapor is purged, liquid fuel can flow past the metering circuit, and now you have the situation of a short soak to deal with, see above. So why not just use a Hot Soak procedure every time? You could, but after you understand why the damn thing won’t start and you think about it, you can use the technique that works the best. If I land the plane, shut down hot, and then go for a restart in less than 10 minutes or so (all thing considered equal), I know that my problem is not at the pump, its at the top lines, so why waste time. Disclaimer: Follow your POH unless you fully understand the pro’s and con’s of using other methods and other’s advice. DVA *As Don Kaye correctly pointed out, the electric fuel pump (on the M20M) is physically in “series" with the mechanical pump as shown on the schematic. The point is that neither of the two are dependent on one another and both can participate alone or together, in parallel, to provide fuel flow and pressure.
  6. 1 point
    [font='times new roman'][size=3]Dennis Dean Bernhard passed away on Saturday, July 11th at his beloved ranch in Harper, Texas. He was born June 9, 1940 in Fredericksburg to Norma Itz and Chester W. Bernhard. Dennis valiantly fought a battle with leukemia having sought medical expertise at the Mayo Clinic in Rochester, Minnesota, MD Anderson in Houston and Methodist Hospital in San Antonio. Dennis married Connie Humes January 25, 1985 at Bethany Lutheran Church, Fredericksburg. They share four children: Chad and wife, Jena Bernhard, Rebecca (Becky) Adams, Cyrena and husband, Kevin Durkee and Brad Bernhard who passed away in 2011. He is survived by one sister, Eileen and husband, Danny Meyer and numerous nieces and nephews. He was preceded in death by his parents, Norma and Chester W. Bernhard, sister Bonnie Bernhard Phelps and grandson, Kyle Bernhard. They have six grandchildren, Father Brandon Bernhard and Kacey, Rianne and Rylea Bernhard; Lillie and Luke Durkee. Dennis was a third generation rancher on the Bernhard Ranch and had a deep love for the Hill Country, rural culture, livestock and wildlife management. He lovingly passed this devotion onto future generations. Dennis was instrumental in starting the Texas Hill Country Dorper Sheep Association and served in all of the officer positions. He was a founding director of Harper Wildlife Association, and served as a director of Gillespie County Farm Bureau and The American Red Brangus Association. A Wrede 4-H leader, Dennis also taught Sunday School for Zion Lutheran Church. A member of St. James Lutheran Church in Harper, he served as a Church Council member. Dennis began his career with Mooney Aircraft where he was service parts manager for 27 years. He and Connie started a new venture in Florida as a partner in ModWork in Punta Gorda, Florida. After 6 and a half years they grew homesick for their much-loved Hill Country and moved back to San Antonio where he began the company, Lone Star Aero, an aircraft service center, located at the San Antonio International Airport. After 19 years Dennis retired to devote his time to his cherished ranch. Dennis and Connie enjoyed traveling together across the United States and Canada in their RV also enjoying the horse races at Kentucky Derby and Preakness. The body will lie in state in the chapel of the Schaetter Funeral Home, Fredericksburg until 8:00 A.M. on Tuesday, July 14th and from 9:00 till 10:00 A.M. in the St. James Lutheran Church, Harper with Funeral Services at 10:00 A.M. with the Rev. Scott Hofmann officiating. Graveside services and interment will follow in the Harper Community Cemetery Pall bearers were Dwight Oestreich, Bob Yelverton, Kevin Kunz, Kevin Durkee, Justin Marschall, and Grant Meyer. Memorials can be given to Texas Hill Country Dorper Association Bradley Bernhard Scholarship Fund, St. James Lutheran Church, Harper Volunteer Fire Dept or the charity of your choice. Visitation for Mr. Dennis Bernhard will begin on Monday, July 13th from 4:00 till 8:00 P.M. and on Tuesday, July 14th from 7:00 till 8:00 A.M. in the chapel of the Schaetter Funeral Home, Fredericksburg[/size][/font]
  7. 1 point
    I normally do not post, I want to let the aircraft owners know that in the last two weeks we have found two cracks in two different aircraft propeller hubs under AD 2009-22-03. Both had been inspected 100 hrs earlier and had shown no discrempencies. Not sure what to think, is it a vibration, time, age that these are just now showing up cracked. We had not had a hub cracked in 15 years so we are treating this very seriously.
  8. 1 point
    Just wondering if there are any other Mustang owners out there?
  9. 1 point
    I beleive that I have the only M20D Master remaining in the original fixed pitch prop/ fixed gear configuration; N1016Y. The aircraft is in KPGD for Garmin ADS-B installation in the next few days. After a four year restoration where the engine, prop, interior, fuel tanks, panels, avionics, lighting, etc were replaced, it is for sale. Anyone interested? For photos and info contact ronmacewen@hotmail.com RonM

*Members that donate $10 or more do not see advertisements*