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jlunseth last won the day on July 6 2015

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About jlunseth

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    M20K 231

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  1. I was just at my A&P where I heard a story about a problem with another 231 they just dealt with. Since the same thing happened to me once upon a time I thought it was worth putting out so other owners would be aware. Might apply to other models with a similar alternator connection (geared). The alternator on the 231 is connected to the engine via a "coupler." The coupler is just a gear, inside the coupler is a rubber clutch, the purpose is to allow the clutch to slip if for some reason the alternator freezes up, avoiding damage to the engine to which it is directly connected. The coupler tends to wear out and needs to be replaced, although good ones will last several years. A prior A&P provided several for me from an aftermarket manufacturer, and they all failed fairly rapidly, leading us to go directly to Mooney for a replacement which lasted, but that is not the point of this post. The coupler fits over the shaft of the alternator and is held on by a nut, which is locked in place by a very small cotter pin. Internal to the coupler there is a bushing that fits between the alternator shaft and the barrel of the coupler. The bushing does not go all the way to the outside end of the coupler, so if it is not assembled by the mechanic doing the work, it's absence cannot be detected by the person doing the inspection and sign-off. If the bushing is missing, the coupler vibrates around the shaft, very quickly beating the cotter pin apart, the nut comes off and the coupler falls off. Unfortunately it, and the nut and cotter pin, fall into the operating engine. If you are lucky (I was), it sits in the bottom of the crankcase and the mechanic can find all the little pieces. If you are not, the engine ingests it, causing all kinds of random mischief inside the engine. So if you have a 231 and need a new coupler, best have the work done by a shop that knows Mooneys, and best to make sure the shop knows that the mechanic actually doing the installation must insure that the bushing is installed. In this instance, it was not my A&P that did the faulty installation, they just got to deal with it.
  2. What he said. See e.g. https://copyright.columbia.edu/basics/fair-use.html#:~:text=Fair Use is a Balancing Test&text=You still need to evaluate,or value of the work.
  3. You must be a city person. Many who go to UND or NDSU have trouble with their grades because they are out on the prairies doing something instead of in class.
  4. An induction leak can play like a flute. Really loud if it is in the right spot.
  5. That situation - the commercial routes to places other than ANC - has been deteriorating for awhile and its a shame. Used to be you could fly Northwest to Cordova from Minneapolis (where I live, and CDV is my favorite salmon river). NWA had a codeshare arrangement with Alaska so it was all one ticket. There was also a codeshare with ERA Aviation, which flew ANC->CDV, so there were plenty of flights available to CDV and back to ANC. You can do MSP to CDV on one ticket with Alaska now, but the flight schedule is not very good. If you fly Delta (which acquired NWA), which gives you a somewhat better schedule, it has to be two tickets, one for the Delta flight to ANC and one for the Alaska flight ANC->CDV. The schedule has deteriorated so there is only one flight a day out of CDV, no more ERA. It turns the trip into a two day affair, and with the two ticket thing, if you run into a weather issue you can bet one of the airlines is not going to be helpful. Just a mess, about half the service there was a decade ago. And that was before COVID.
  6. Congratulations! And its nice you would share it with us. I skipped the ME, don’t know when I would ever fly a twin, my Mooney is so smooth, fast and fuel efficient. My thought is ATP-SE, no requirement of a CTP course or a college degree, just get in the 1500 hours, sign yourself off to take the written, and then do the practical test. Very strong on instrument skills, which is what I want. Best of luck whatever you do.
  7. Well, but rate does raise a little bit of an issue doesn't it. "Best rate" does not mean that the rate goes up when the aircraft is at, say, 20,000, versus when it is at 10,000. "Best rate" only means, at what airspeed can the best rate of climb be achieved at a given altitude. If the rate goes down at 20 versus at 10, then the pilot must have found it necessary to fly faster to keep the rate up as high as possible, even though that rate has declined. Hypothetically, at an altitude above critical altitude, the pilot may need to fly at, say, 160, in order to keep the climb rate at 100 fpm, and the pilot in my hypothetical will find that 100 is best rate. So isn't that the answer? The increase in the airspeed required to make "best rate" - whatever that is for a given aircraft at a given altitude - must increase because the wings generate less lift in the thinner air, and must pitch higher to achieve that lift. Not too long after critical altitude the aircraft will reach an altitude where it cannot fly fast enough to achieve any climb at all, and if it flies slower it will descend. Classic coffin corner math.
  8. I made the switch about a year and a half ago. Unit had to go in to JPI and came back looking new. My unit was about 8 years old by the time it went in. Newer units, I guess, can use the frequency based probes but the older ones need to be changed. Probably serial number based. JPI has been very slow during the COVID shutdown, so I would check with them to see how long it might take. The charge was nominal, maybe $350, I don’t really remember.
  9. First I have a question. What is the basis for stating that Vy increases? Is it stated in the POH (or STC), or are you using your VSI and noticing an actual condition of your aircraft in flight? I don't know that I have a great answer for you, but I have a clue. My aircraft is a 231 with an intercooler, Merlyn, and a JPI 930. The 930 has an algorithm for percent HP when Rich of Peak. I have noticed that, on takeoff at my home airport (910' MSL), 100% HP is around 2700 RPM's, full rich, and 36" of MP, or maybe a little more, say 36.5". However, as I ascend into the flight levels, 100% HP can be achieved at lower MP's. It is somewhat OAT dependent, but I have seen situations where the algorithm reports 100% HP in the 32" range. I don't know how JPI's algorithm is structured, and in my aircraft it comes up with a percent HP that is probably about 8% low most of the time. Nevertheless, at least according to JPI's algorithm, if power is set (ROP) at 36" on takeoff and that 36" is maintained up into the flight levels, the algorithm says that the engine output actually increases to somewhere in the vicinity of 110%. Notwithstanding the Merlyn, MP is pilot controlled in the 231, but not in turbo aircraft with fully automatic controllers. In those aircraft it is set and forget - firewall the throttle on takeoff, the engine makes, say 36" (depends on the engine), and at FL210 or any altitude less than the critical altitude, the MP will still be 36". The JPI algorithm, however, seems to say that power output has increased by as much as 10% even though MP (and RPM and fuel flow) has remained unchanged. So that could explain why Vy is observed to increase.
  10. During the first turn in a spin, a better strategy than PARE is PUSH ROLL POWER STABILIZE. The PUSH should be automatic. The first turn is an incipient spin. Although the aircraft is beginning to spin, the spin forces have not fully developed and you can break out without PARE. Wait more than one turn and PARE is the only way to go.
  11. Their course - the full course I mean - is well worth it.
  12. Ah, a thought for you on the alt air door. I wonder if you haven’t solved that problem but you just don’t know it yet. First, I was trying to puzzle out in my head how painting could jam the alt air door and I just don’t think that would do it. I can see how, if the paint shop failed to cover the induction intake and then sprayed into it, the filter could get clogged. But the alt air intake is inside the cowling so it would take some doing to hit it with paint. In the original 231’s pilots would sometimes get into trouble with induction icing, fly into a cloud of snow or ice crystals and the air filter would clog, starving the engine for air and bringing the plane down unless the pilot figured out what was happening and pulled the manual air door knob, admitting warm intake air from inside the engine compartment. So the door was converted to an automatic door. If the air filter starts to plug, the door activates. The automatic system was installed in all the subsequent turbo models. I think that is your answer. The automatic system detects the plugged filter and opens the alt air door, feeding warm air in from the engine compartment. If you have cleared up the plugged intake that should have eliminated the problem, but if you have a manual alternate air knob you might work it back and forth a few times to see if that makes a difference. I suppose it is also possible there is a spring or something that holds the door in the normal position, and that has failed. Worth checking. But you might just try a couple of flights now that the air filter has been replaced and see if the problem has gone away on its own. I don’t think there is any doubt you were sucking in engine compartment air when the plugged filter was there, that may have been the only way the engine could operate.
  13. PS on your JPI alerting on the CDT temp. When JPI sets up the unit to deliver it to you, they program in two types of alarm limits. The first are the alarm limits that are in the POH for your engine and are required to be present. For example, my RPM limit in the POH is 2700 so that limit is programmed into the 930. The second set are limits that are not in your POH and do not apply to your aircraft, but JPI puts them in anyway. These are purely arbitrary limits set by JPI. As an example, there is no fuel pressure limit in my POH (M20K 231). JPI sets at least a lower limit (I have never seen an alert on an upper limit so don’t know if one is programmed in). However, the lower limit appears to be set with cruise power in mind. The result is that when I am taxiing normally, I get a flashing red alert that fuel pressure is low. In this instance, fuel pressure is not abnormally low, the JPI just has no way of distinguishing between cruise and idle operations. It only “knows” that FP has fallen below the arbitrary limit programmed in by JPI. Just about every Mooney instructor, and every DPE who has ever flown with me asks why the fuel pressure is low during taxi, so now I go out of my way to explain how the JPI system works and what kind of irrelevant (and relevant) alerts they may see. The low FP alert is not a bad idea. If I were flying along at a cruise power setting and my fuel pressure were to suddenly drop to 3.7 GPH I would want to know about it, undoubtedly the engine would already be letting me know there is a problem. However, when I taxi I just ignore the alert, 3.7 GPH is normal for that regime of flight. How and why JPI sets these alerts is known only to JPI. I surmise that since they sell units used in aircraft such as the factory 231 (nonintercooled TSIO360GB/LB), the unit programming requires that a CDT be programmed in and they just pick one that makes sense to them. In this case, unless there is a CDT limit stated in your POH you can ignore the JPI set limit. TIT is the limit to watch, and if in your POH, then IAT. The alerts you should observe are the limitations in your POH. The rest of them you will just need to figure out when you can ignore them. The other thing worth mentioning about the JPI is that its instrumentation is more sensitive than the factory analog stuff, so it will read variations and may alert on variations that the factory instrumentation would not even have “seen.” For example, I will occasionally see 2710 or 2720 for RPMs. A variation of 10 or 20 rpms would have been barely visible if at all on the factory gauges (which are now gone). I don’t actually know how the JPI is programmed, that is proprietary, what I am telling you comes from 10 years of having and using one on my panel, and sometimes when I had questions (like the CDT/IAT thing), asking some people who are engine experts so I understand.
  14. I went into the CDT/IAT issue with several experts when I first got my 231, which has an aftermarket intercooler. The 231 has a published CDT limit, but that is for the factory engine which has no intercooler. What I learned is that if there is no intercooler, then CDT is important. In that type of engine configuration, CDT is IAT or thereabouts. A CDT limit is set to protect the engine from pre-detonation or actual detonation because the induction air is too hot. However, when there is an intercooler, CDT is not important. The IAT will be somewhere in the vicinity of -50 to -125 degrees from the CDT depending on the day conditions, airspeed, etc. The CDT limit you might see in a nonintercooled engine has nothing to do with protecting the turbo, TIT is the temperature for that. What is relevant is the temperature of the induction air. Most engine gauge set-ups do not show both CDT and IAT. You must have the JPI 930, which does have that capability. But you can safely ignore CDT for an intercooled engine. In theory, I need both CDT and IAT in my 231 because of the aftermarket intercooler. It comes with a table that tells you what MP to use that would correspond to what is in the power tables in the POH. That MP is determined in the STC table using the differential temperature - the difference between CDT and IAT. But I don’t think that is an issue in your Rocket, is it? The Rocket engine is intercooled from the factory and the power settings with the STC should already take into account the differential temp. When the alternate air door is closed there is a slight power drop. The intake air is hotter. So if your door is jammed shut by paint that would make some difference in power output. I have never noticed it makes much difference though. My first guess with your issue would have been that something happened with the baffling when the cowling went back on at the paint shops.
  15. He was on an IFR flight plan the next day, look at the altitude and route filed.