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Mike Koerner

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About Mike Koerner

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    Co-Pilot Member

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    Palos Verdes, CA
  • Interests
    flying, soaring, sailing, climbing
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  1. Blue, Years ago, my father had a similar problem with a much heavier aircraft. His solution was to attach a starter motor to a wire drum such that it would free-wheeled in one direction and motor in the other. The device was affixed to the back wall on the floor of his hangar. He could then taxi up, turn the tail toward the hangar, shut down, walk to the back of the hangar, retrieve the hook on the end of the wire, pull it out and attach it to the tail tiedown ring (Yea, I know. But you could probably use the tail tiedown strap instead, especially if there was a short nylon leader added between the hook and cable.). He used this homemade contraption to winch his plane into the hangar tail first. It looks like there are commercial units now that work the same and use ac wall current.
  2. The trick may be not to own stuff. Just rent instead. Let someone else worry about maintaining it.
  3. 1 to 2 amps is huge. 1 amp is the normal current to a Dynon D100 when it's all lit up and operating. It's maximum current (when it's recharging its internal battery) is only a little more than 1 amp. It can't get to 2 amps.
  4. That's great news Corey. I sure appreciate your contributing to this forum again (even though I'm not worried about water in my fuel).
  5. Corey, I'd like to clarify one thing you said: The speed at which the maximum glide angle is achieved is sensitive to weight. The maximum L/D (lift to drag ratio or glide angle) does not change with weight, but the speed at which it occurs goes up with weight. It increases by the square root of the ratio of weights. So, if you've determined your max glide speed is 73 knots at max gross, and you're flying alone and without baggage and low on fuel at 900 lbs instead, then your best glide speed will be 73 x (900/1320)^.5 = 60 knots. That's an extreme case of course. And note that you will not glide any farther at lower weight. You'll end up in the same place whether heavy or light. But if you're light and flying at a lower speed, you'll have more time to consider your sins on your way down. A rule of thumb is to reduce the maximum glide speed by 5% for every 10% you are below max gross. In the example above, you were at 68% of max gross, so the rule of thumb would suggest 16% lower speed or about 61 knots. Maybe that speed difference is not enough to worry about. The L/D curve is flat near its maximum, so a little more or less speed probably isn't going to break any branches. Wind, of course, will also come into play. Another rule of thumb is to increase speed by half the head wind component and decrease speed by 1/4 the tail wind component. The inverse of this is to add weight when you want to glide fast. My sailplane holds 44 gallons of water. On strong summer days, I load it up until water is gurgling out the vents.
  6. Mike Koerner


    Tommy, Thanks for sharing this EASA report. It is well written and interesting. That said, it’s from 13 years ago. In the US we had just recently started using E10 (gasoline blended with 10% ethanol). It seems to me that this report reflects potential issues and concerns with the use of E10, not actual problems. Notice, for example, Rotax participated in the FMEA (Failure modes and Effects Analysis, which is essentially brainstorming potential problems and rating their risk based on estimated severity, probability, and detectability. This was used to define areas of concern for the subsequent study.) And yet, Rotax later approved the use of E10 in their engines (and so has Flight Design approved E10 for use in their aircraft). So clearly, subsequent to this FMEA, they collected sufficient data to convince themselves that E10 is not a problem, at least not for the CT aircraft and Rotax engines. I’m sure I’m guilty of creeping normality (where we decide it’s OK to launch because it’s only a little colder than the coldest temperature the solid propellant boosters have ever operated at before, or we decide that ice falling from the external tank, which has damaged the shuttle’s thermal tiles on every previous flight, probably won’t cause catastrophic damage this time either). Yet, in 2000 hours and 15 years of flying my CT2k, mostly on E10, I have not had (or at least have not detected) any of these problems. And of course, the other members of this forum represent a much greater level of experience with E10. With respect to phase separation (conclusions on page 74), I’ve left my plane out for up to a week in torrential rain; and I’ve run my tanks from full, down to a couple gallons on each side, during a single flight (which EASA thought might be a problem), without experiencing this. I don’t recall anyone on this forum having a problem with phase separation either, though some concerns are mentioned above. The US Environmental Protection Agency (yes, I recognize they are not responsible for flight safety) has said phase separation won’t happen with E10 over the course of a "winter storage season" (I don’t know what the storage conditions were). With respect to icing (conclusions on page 79), from the jungles south of Mexico City to the Artic Circle, from Catalina Island to the Bahamas; in rain and in snow: I haven’t experienced this. And again, others on this forum have flown in a wider range of conditions. And yet, only a couple have ever mentioned what they thought was carburetor ice, despite that fact that many of us are using E10 and (improperly) never use our inlet air preheater (carb heat) at all. With respect to vapor lock (conclusions on page 93), though I’ve never let any of my engine temperatures get near critical levels, others on this forum have, and again, I recall only one or two mentions of possible vapor lock. With respect to material compatibility (conclusions on page 125), there was a problem with our original plastic fuel filters. A service bulletin was issued to replace them, and new metal filters were distributed free of charge. If I remember correctly, my plastic one was substantially deformed at the time of removal, but not yet leaking. With respect to elastomers, I know of at least one owner (whose name I shall not mention) who let his rubber parts go well beyond the manufacture’s recommended 5-year replacement interval, with no fuel compatibility issues evident. And the wing’s thermoset resin is (at least mostly) protected from the fuel by a special coating applied to the inside of the fuel tanks. The EASA document also includes a discussion of water detection (conclusions on page 135), but absent a problem, I don’t see the need for detection. And finally, there is an analysis of whether adding alcohol to fuel is going to save the world or not (conclusions on page 143). That would be a subject for a different forum. Despite the title, the “Executive Summary” on page 161 is actually just a tabulation of FMEA, which they did not include in total because, they say, it’s in German. At 36 pages, this appendix was the source information they used for the FMEA section of the main report, which covers 10 pages (51 – 61) and has its own conclusion (page 61). So, I don’t know… but I’m going to continue using E10.
  7. Mike Koerner


    Here's an interesting study from the university of Nebraska. In summary: 1) E-10 will hold up to 0.41% water (3 teaspoons per gallon) in solution. Below this threshold, the water will have no significant effect on combustion. There will be no loss of octane and no separation of the water or alcohol. 2) Higher concentrations of water in the fuel will cause a phase change with the water and alcohol mix separating from the fuel. The engine will undoubtedly run poorly when this separated alcohol & water mix is ingested. And, as suggested by the Johns, the separation of the alcohol and water will likely result in a reduction of octane in the rest of fuel. 3) Though E-10 draws moisture out of the air, it cannot absorb enough moisture to cause the phase separate over the course of a "winter storage season". I don't see water ingestion as an issue with E10 fuel. In fact, I think the alcohol is helpful in avoiding the water separation issues common with aviation fuel. That said, I would prefer pure gasoline for its 3.3% higher energy content, but I wouldn't pay much extra for that.
  8. Mike Koerner


    John, I'm surprised by your first deduction, that water absorbed into the ethanol decreases the octane. I would expect water to increase octane. Remember that octane is a measure of the resistance of the fuel to pre-ignition (knock). Water is not going to contribute to the combustion process at all. In fact, it seems like it's vaporization in the combustion chamber would lower combustion temperatures, inhibiting pre-ignition. Of course, there is not enough water in our fuel for this effect to be significant. And we wouldn't want to use water to increase octane anyway, since it is not contributing energy to the process.
  9. Updated conclusions: 3) You don't need the audio alert in flight but you do need it to perform the quarterly system checks prescribed by ACK. It may also be useful in detecting inadvertent ground activations. I put mine back in, with another new battery, and it seems to be working fine now. 2) This leads me to believe that the battery corrosion I observed did not cause the spontaneous in-flight activation. I now think it was just water in the RJ11 cables. I also think that disconnecting the cable ends, and leaving them off for a week, was critical in allowing the water to eventually dry out.
  10. I switched from a 121.5 Ameri-King to a 406 ACK ELT a couple years ago, then had a spontaneous in-flight activation a few months ago while on a trip back east. The plane had set outside on the ramp at Elmira, NY through a couple days of heavy rain. There was about an inch of water in each of the foot lockers which I sponged out before flight. About 45 minutes into the flight, I heard the whoops of the ELT on the comm radio, even though it was set to a Unicom frequency. Apparently, the proximity of the ELT and comm antennas, or their coax cables, allows frequency crossover. Pushing the reset button on the ELT remote provided only momentary relief. I landed at the nearest airport, Warren Eaton, and disconnected the battery compartment from the rest of the ELT main unit to insure it would not broadcast again (the OFF position on the switch on the ELT main unit, as opposed to ARM or ON positions, undoubtedly would have achieved the same thing, but nothing I tried from the remote was successful). ACK suggested that the system is susceptible to spontaneous activation when the remote, audio alert or RJ11 telephone cabling is wet. They also indicated that battery acid corrosion in the remote or audio alert, specifically with Duracell batteries, could also be the problem. After putting the unit back together at home a couple weeks later, it was still stuck ON. Even after replacing the remote, it was still misbehaving, though in a different mode. At that point I opened the audio alert and found corrosion on the Duracell battery. Replacing the battery and even bypassing the remote, did not seem to completely solve the problem at first, but a week later, with the audio alert still bypassed, the system was working fine. A further note of possible of interest, though not central to the ELT discussion, is what happened as a consequence of the ELT activation. After landing and deactivating the machine, I was wondering who to call to ensure that no one was searching for me. A nice gentleman at the airport, giving young eagle rides with a beautiful red Maule, suggested I call 1-800-WXbrief, the FSS stand-in, and tell them what happened. I did. They said they would take care of it. Hours later, before landing back at Elmira, I started getting text messages from my wife asking if I was alright. Then when I landed, the FBO handed me a note with a phone number to call. It was the Air Force search and rescue operation in Florida! They hadn’t sent anyone out looking for me yet, but they were going to. Furthermore, they had called my wife, 2000 miles away, asking if she knew anything about an emergency signal from my aircraft!!! That did not go over well. My conclusions: 1) Our planes are not waterproof and should not be exposed to sustained heavy rain. 2) My ELT seems to have suffered from both battery corrosion in the audio alert and from water in the RJ11 cabling, which finally dried out a week after I replaced the remote and bypassed the audio alert, many weeks after the initial water exposure. 3) The audio alert is not needed in flight. Our own ELT broadcasts can be heard, loudly, on any radio frequency. Furthermore, the audio cannot be heard over background cockpit noise or with noise canceling headsets anyway. 4) Make sure you disengage the Air Force after an inadvertent ELT activation. 1-800-WXbrief is apparently not the way to do it. 5) Use someone other than your wife as your emergency contact.
  11. MEH, Well done sir! Excellent deductions. Congratulations. Years ago, I came across a similar theoretical situation where it was my own stupidity that left the cap setting on top of the pump in the other LA. I discovered my error at a stop in Texas and went the duct tape route too… but I duct taped in a straw as a ram air vent. However, by my next stop the duct tape had dissolved. So I replaced it with what my logbook describes as a bottle cap. I don’t remember the details of this, but I think it was still held in place by duct tape, with the cap acting somewhat like your doubled over tape, protecting the adhesive. The next log entry says it wasn’t drawing fuel from that side and that I stopped again and “vented the bottle cap”. The next leg I remember perfectly, and probably always will. It was night. I was crossing a poorly lit stretch of southern New Mexico, heading for Lordsburg. Watching the sight tubes, the situation was becoming way more exciting than I felt like I really needed. In an unusual moment of clarity, I turned 90 degrees and landed at the nearest airport, Las Cruces. On landing, the wing with the normal cap was completely empty while the tank with the vented “bottle cap” was completely full; just as you had observed. But I hadn’t figured out your “pinch the line” idea. Instead, I waited 3 hours for the fuel to level out between the tanks, by which time any remnants of sanity had evaporated, and took off again into the night.
  12. Flapper, I suspect that inspection procedure applied to the original design, with a spring in the strut. Since they changed to plastic donuts, the front suspension is very stiff. There's probably more play from compressing the tire.
  13. Mike Koerner


    Very nice Ken. I flew through there once, but I didn't get to see all those pretty buildings. I was too worried about the helicopters.
  14. David, Thanks for the description and photos! Tom, Thanks for explaining these pushrods. Dick, I hope I don't have your problems. It's not flutter in the control system I see, just the tab vibirating and the hinge pins wearing. Andy, If my rod ends are lose, I think I'd go the 53 Euro route, like David, rather than try to glue them together (and no, you can't weld aluminum to steel, or a thick part to a thin part either).
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