jlunseth

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jlunseth last won the day on July 6 2015

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About jlunseth

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    KFCM
  • Reg #
    N381SP
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    M20K 231
  1. @pkofman. I am responding to your last post. I see that there have been a few since then. It would indeed be weird if individual EGT's, or even one of them, exceeded TIT. TIT is invariably higher than EGTs. We have had some discussion about why in past threads, its not really important and technical, its really only important to understand that is the way it is. Think of it this way, the engineers who designed the engine found the most important point at which to protect the whole exhaust and turbo, and that was at the inlet side of the turbo. As long as that is within the redline limit, everything else will be fine. So from the standpoint of protecting your engine, the TIT redline, the absolute number, is the important one. CHT's also of course, but they protect the cylinders not the turbo. There is no need or particular usefulness in noting EGT differentials. Now, if you have a 250 degree differential, that might tell you there is a problem that needs looking at. But within normal operation limits don't bother. In installing the probes, the mechanic in most cases must put some probes a different distance from the exhaust port than other probes, and the manifold geometry is not always the same for each cylinder right where the probe is installed. Which means that respective probes won't "see" the same termperature. Which means that differential EGT is a function of probe installation and probe calibration (as in, they are not calibrated to read the same) as much or more than it is actual temp difference. The way to determine if the fuel/air ratio is the same or nearly the same for all cylinders is to run a lean test. APS, and because most of them follow APS, all of the other authorities in the field, want to see a differential of .5 gph. You can find instructions for the lean test on the APS/GAMI website. I don't disagree with the guys who say use TIT when running your Bravo. First, you always use TIT, you use it because you don't want to exceed redline. It is less useful as a way to determine where you are running your engine, in terms of degrees LOP or ROP because of what carusoam touched on, if you don't use EGT's you can have several cylinders running where you want them, and one or two sitting right at peak or in the red box, which you don't want. That isn't to say that if the Bravo POH says lean "x" degrees from peak TIT, that was not good advice at the time. The problem was that engine analyzers were for the most part not present to give us better readings when those things were written. And as I said, if you have an analyzer, and you know where your EGTs are at a given power and fuel flow setting, and its easiest to just set to a TIT because you know that everything else will be good, then by all means use TIT. I might add, I don't have a Bravo and from everything I have read here and elsewhere, the Bravo does not like LOP much and not many Bravo guys fly that way.
  2. You have gotten pretty good advice, there is not much to add, but here is a little. We treat TIT as an absolute number and EGT's as relative numbers. In other words, it matters whether TIT is 1600 or 1700 - it matters what the absolute number is. It does not matter what the absolute EGT numbers are, it matters what they are relative to peak EGT. TIT has a redline and is there to protect the turbo. The turbo runs at speeds upwards of 100,000 and if it gets too hot, the lower deck blades will stretch. The tolerances inside the housing are already close, so blade stretch leads to the blades contacting the housing, and we don't want that. There are other things that happen also, but that is the main concern at high temps. This ahs to do only indirectly with how far LOP or ROP you are running the engine and at what power setting, indirectly because most likely if you see a redline TIT it is because you are running the engine wrong, but there are other contributors such as a hot day or poor cooling due to altitude. You should go over to the Bravo forum and read some of their engine setting stuff. The Bravo and Acclaim guys tend to run their engines at somewhat higher TITs than I do in my 231. I use 1600 and it works, my turbo is fine after many hours of operation. EGT's are relative. We don't care what the absolute number is, and once you have figured out how to set your engine up for a given phase of flight and desired power output, looking at the EGTs becomes less important. We use EGTs in setting fuel flow an turbo output (MP) because it tells us how far from peak EGT each cylinder is operating. There is always some variance in fuel flows among the cylinders, and it is important, in deciding where to run relative to peak, to use the EGT closest to peak. From the rich side, that is the first cylinder to peak, and leaning over from the rich side to the lean side, that is the last cylinder to peak. If we use these temps, then the other cylinders will all be further from peak and well protected. We normally don't use TIT for this, because TIT doesn't say where each cylinder is, so it is possible to have, say, four cylinders running nicely rich of peak, one more rich, and one running lean and sitting right in the red box. All that side, if you have properly leaned the engine a few times using EGTs, and you know that , say, at 29" and 1600 TIT the leanest cylinder is always at 125 degrees ROP, and you are fine with running that cylinder at 125 ROP, then by all means use TIT and use CHT. I hardly ever look at my EGT's anymore, one of my favorite settings is 11-11.1 gph, 34" MP and TIT at or under 1600. I have run the engine enough at that setting that I know the EGT's will be fine, and I check them only, say, if the fuel flow has been rejiggered at annual or something of that nature. Let me hasten to add, this setting is for my 231, not for your Bravo, ask the Bravo guys what they do.
  3. The better question is why do we have three logs to begin with? Why not just one? My prop log has about three entries in it over 15 years. What's the point? I don't think the regs require three logs, they just require that maintenance be logged.
  4. I have the KFC200 so I hope this is headed in the right direction. Having the factory repair or replace components (i.e. the 256 and 525) is alot different than repairing the AP itself, which is installed in the backbone of the aircraft, so the whole aircraft would need to go in. But the actual notice from BK appears to consider that, good for them. I think we need to bear in mind that BK has been a pretty good citizen of GA to date. They have allowed shops like AP Central and their has been a healthy market for rebuilt components. On top of that, many of these systems are 30 years old or more, and were designed in a completely different era when there was no GPS. The fact that ways have been figured out to make them work with GPS is, to me, remarkable, whether BK did that or not. I have mixed views about Garmin as a GA citizen. Their developments in GPS have been remarkable, but they are very pricey, there have been bugs, and their service system does not always work well. I had a 430 AW installed in 2009, the "A" is for the $3,500 extra I paid for to have a 16 W transmitter because I fly in the Flight Levels and long trips over the midwest where distances to the nearest transmitter are lengthy. The thing has not been worth the money since I bought it. Both transmission and reception have been mediocre at distance, or around Tstorms. I generally revert to my second comm, a beat up old King, when I lose contact on the 430. Its a much better radio. I have tried to get the problem solved several times, have had replacement units installed, and through my local shop we sent the unit in to Garmin at one point. The report was that it was out of spec, they returned it to spec on the bench at Garmin, but it did not make much difference. So why did I spend that $3,500 in the first place. I was at the Garmin factory during a Mooney PPP, there was another pilot there with the same problem with his 430AW, we both asked about it, we both were told to work through our local shop, which both of us had done repeatedly. I was also not impressed with the G1000 non-WAAS issue, which as I understand it still has not been resolved except at a megabucks cost for those unlucky enough to have the non-WAAS G1000 in their plane. Don't get me wrong. I love Garmin's overall design approach. The GPS part of my 430 has been absolutely bullet proof and the single best upgrade I made to the panel back then. And I don't want to see BK back off on their past support of GA. I just think there aren't any of them that are perfect citizens. Why the heck do I pay$10,000 for an installed GPS, when the consumer GPS is sold for $300. In the 90's I flew as a passenger in charter flights out to the Bahamas where the pilot had a consumer unit in a bracket on the yoke. Worked pretty good.
  5. Yeah, hanging around the trap/skeet clubs a few years ago I met alot of men who had a lifetime of shooting with no hearing protection or with at best tissue stuffed in their ears. I noticed that all of them, if they wanted to have a conversation, would walk up, touch someone's arm, wait till the person turned to face them, and then started talking. Every last one was a lip reader. They had a trap mechanic at the club for awhile who had been a tank mechanic in the service, and who had fired the 50's on the tanks quite a bit. When he pulled trap, he couldn't hear a thing. You would have to wave your shotgun barrel so he knew it was time to throw the target.
  6. Be very careful with that. There were some insulations installed to do just that, but their thickness and the material type meant they held moisture, and the edges of the insulation are up against the tubular frame members. I had to have some remediation done on the frame, including cutting out and replacing some of it, when I first bought my plane. I just took the thick insulation the heck out of there. The biggest source of sound in any event is through the firewall.
  7. I completely agree. I did quite a bit of shotgun target shooting in the 90's and hearing protection was a concern. One of the issues with plugs alone is that hearing damage can continue to occur because of sound induction through the bone behind the ear. I used foam plugs quite a bit, but the problem with them was that I couldn't hear anything, it was difficult to hear normal conversation and the clicking of the trap machine releasing a target was inaudible - and they were not complete hearing protection. I liked muffs better because the hearing protection was better, but they weren't perfect either. The two together was too much, could not hear anything. I use A20's. They are really good. I have a 231, and the Bose certainly tames down the engine noise. Makes it much easier to talk on the radio. Are you sure your noise cancellation is working, because it doesn't make sense to me that engine noise would be that loud.
  8. I put my home base in my profile - KFCM . You can add me to the map, and thanks.
  9. The main problem is sitting. Not hours running. if you are only flying 75 hours a yesr then you should be changing every 20-30 hours. if flying 150 hours a year, 40-50 hours works fine. Why use costly synthetic if you are only going to run it 20-50 hours between changes?
  10. i agree with the "wave" post, but it is not necessarily a true wave, just descending air. its fairly common at all altitudes.
  11. I have ADSB and SatWX, no stormscope. I much prefer the SatWX over ADSB. I often need to look several hundred miles ahead on long trips, and ADSB just does not do that. It give you a "puck" of about a hundred miles. Example: a couple of years ago I was flying some friends to KRAP. Storms form over the Black Hills in the summer and spill out to the east over KRAP. That particular trip they were spilling out directly over the airport. They were forecast to clear by our intended arrival time, but SatWX told me that was not happening. So I just slowed down quite a bit, to give them time to clear. Worked really well. It would not have worked at all, except that I could see what was happening 400 miles out and allow for it. So I have kept my SatWX subscription and don't use ADSB much at all. I am not sure what a stormscope would add, I prefer not to penetrate at all, and use the Mark I eyeball to find clear air.
  12. I have dialed in approaches a few times, to make sure I am on the right runway. But the moving map is pretty good, I can see where I am supposed to go. I do always check my heading indicator when I am lined up on final, at airports where there are confusing and multiple runways. Some are a little mystifying though. KSTP has a 31 and a 32. I don't get that. Parallels I am fine with, but runways 10 degrees apart?
  13. Made me laugh. That is pretty much the same as my first time there. Now I look for the big obvious airport, and then the little, not-so-obvious one to the left. And practice your crosswind landings before you go.
  14. I go to KRAP a couple of times a year. First time there it was hard to find the GA airport and it would have been easy to land at Ellsworth instead. Thankfully, I followed the moving map to the right airport and ignored what I saw out the window. Sure enough, a year or two ago a regional jet, I think it was a Delta flight, landed at Ellsworth. Oops! I really think Ellsworth Approach is as much at fault as the jet crew. That's an easy mistake to make and they should have been watching. I am sure more than one aircraft has done that.
  15. Well, its certainly a single engine.