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  1. Dan Thomas

    Wing sump

    It's either water that has frozen in the sump, or the valve is seized.
  2. Dan Thomas

    Why is my mechanic so against a turbo?

    Some turbo systems are automated. Fully-mechanical, though, since electric stuff tends to fail too often. This system has been around a long time. Go here and read about it: https://www.extraaircraft.com/docs/tech-manuals/MM400/81r1.pdf A diagram of the system: Some systems don't have the...
  3. Dan Thomas

    Why is my mechanic so against a turbo?

    You can get too much boost if the engine isn't handled properly, especially in manual wastegate systems, where the wastegate is linked to the throttle. That high induction pressure can lead to detonation, which trashes cylinders. It shatters rings, cracks pistons and heads. Exhaust systems...
  4. Dan Thomas

    Floatplane incident Miami

    Don't have to rupture the whole float. Just bust it open enough so that a couple of the compartments fill. The remainder aren't enough to keep the float on the surface. You will note that there had to be some buoyancy remaining, otherwise the airplane would have turned over. A Caravan out of...
  5. Dan Thomas

    Slick Magneto Failure

    By the time you pay for that kit plus the labor, you might be better off buying a new magneto. A good mechanic can determine if the coil or distributor are shot. That same good mechanic will have the Slick (Champion) magneto maintenance manual, too, which tells him all he needs to know so he...
  6. Dan Thomas

    Tire balance and runout tolerances

    Bent or cracked or distorted wheels must be replaced. They are cast aluminum, then the inside of the flange and bead seat and the radius between them is roller-hardened to discourage cracking. And welding or straightening is going to just make things worse. From the Cleveland manual: No...
  7. Dan Thomas

    172 seats

    I have electronic copies of both the '53-'62 and '63-'68 100 series manuals. No mention of the seat swap in the earlier manual, and no revision date on the page that would have it. That's the manual that applies to the 172B owned by the OP. In the later manual I see this: Now. in both...
  8. Dan Thomas

    172 seats

    Using parts from a later model can get problematic. Somewhere in the FARs there is (or was) a requirement that only parts specified in the manufacturer's parts catalog for that serial number or airplane could be installed, or their equivalent such as a PMA'd part, or under an STC. The parts...
  9. Dan Thomas

    MIF stuck ptt + solution

    We had a Cessna come in whose aileron controls were stiff. Someone had put a long screw into the plastic doorpost cover on the aft doorpost, and that screw had run up against the aileron pulley at the bottom of that post and jammed it. The cable was dragging over the pulley. Lots of friction...
  10. Dan Thomas

    Lycoming exhaust stud repair - Helicoil?

    Sorry, but I am very familiar with pipe-thread helicoils. In my 12 years as a foreman in an air brake component remanufacturing plant, we went through thousands of those things, from 1/8" NPT up to 3/4" NPT. They are for stripped or torn PIPE threaded ports, NOT for studs. Lycoming has threaded...
  11. Dan Thomas

    Lycoming exhaust stud repair - Helicoil?

    A Lycoming exhaust stud. You can see that the thread on the right is a tiny bit larger in diameter. That's the oversized end that screws into the head casting. No taper.
  12. Dan Thomas

    Top Overhaul vs. Full Overhaul

    My experience with the term "top overhaul" means that the cylinders were removed and disassembled. Valves out. Dimensional checks on the cylinder, piston, valves, valve springs, rockers, pins and guides. Hone the cylinders to break the glaze. Clean the pistons and install new rings. Grind the...
  13. Dan Thomas

    Starter not disengaged

    Not with a Lycoming. Lots of noise there. In a Continental you won't hear anything at all unless you're hearing is sharp enough to hear the starter itself still running due to a stuck starter contactor. The starter drive makes no noise. In fact, in the small Continentals, with the key start (not...
  14. Dan Thomas

    Slick Magneto Failure

    But exactly right. That there. Do you have an electronic tach?
  15. Dan Thomas

    RR tracks: How close is too close?

    The type of soil matters, too. Some soils really transmit the vibrations, and if the train is fast and heavily loaded, the house is going to shake. We live in a tiny town in Saskatchewan. There is still a track here, but a short train runs through once a week, usually around 11 am on a Tuesday...
  16. Dan Thomas

    Starter not disengaged

    Even if the gear stays engaged, it has the one-way clutch behind it so the starter doesn't over-rev. Once had an R182 (Lycoming O-540) where the light Bendix return spring had broken. I heard a tinkling noise as the airplane taxied up. The starter gear was touching the ring gear. Now, if that...
  17. Dan Thomas

    Lycoming exhaust stud repair - Helicoil?

    The Lycoming studs are a bit oversized on the engine end so that they're an interference fit in the casting. That's so they don't back out when you're removing the nuts. They're not tapered; they just feel that way when they're going in. They'll fit tight in a helicoil, and that's OK.
  18. Dan Thomas

    High CO Readings

    An alternator or vac pump failure at night, especially over sparsely populated areas, or in IMC, can be a really bad deal.
  19. Dan Thomas

    High CO Readings

    Stene Aviation for that stuff. Fiberglass, which is repairable, and they are far cheaper than the OEM plastic junk.
  20. Dan Thomas

    High CO Readings

    Owners are fond of flying stuff until it fails. Mags, vac pumps, alternators, lots of stuff. One wonders why they bother to put gas in the thing.
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