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Compression check required per FAR 43 Appendix D

in General Tech Discussion 12 years ago
FAR 43 Appendix D says that a compression check is required (where applicable).

I am taking the LSA Repairman Inspection course this weekend and the instructor has confirmed via email that it is required on the Rotax.

It is interesting to note that nowhere in my engine logbook is any reference made to having ever checking compression.

I have a Rotax 582. The instructor said that a "direct" check, using a gauge that screws into the spark plug port is all I need.

What are you guys doing?

  • Re: Compression check required per FAR 43 Appendix D

    by » 12 years ago

    Mike,

    Since there are no valves to contend with in a 2 cycle, the pressure differential test,or leakdown test, isn't really necessary. An automotive type screw in compression gauge is all you need. Just take one plug out of each cylinder, screw the gauge into one of the empty plug holes, put the throttle on wide open, LEAVE THE MAGS TURNED OFF, and spin the starter 3-5 seconds. Repeat with the other cylinder and you're done.

    Bill.
      
    Report

  • Re: Compression check required per FAR 43 Appendix D

    by » 12 years ago

    I cannot turn the mags off. I have the turn key type of switch that goes thru both mag positions, then both and then start.

    Can I just remove the spark plug caps?
      
    Report

  • Re: Compression check required per FAR 43 Appendix D

    by » 12 years ago

    Mike,

    If you can't turn off the mags, care must be exercised here. If you pull off all four plug wires and crank the engine, you can damage the E boxes. The voltage from the mags cannot go to ground and will overheat the electronic components.

    If you have an extra set of plugs, you can pull the wires from the engine and plug them in the extra plugs. Then ground all four of the extra plugs to the engine block. This will give the voltage a route to ground.

    Other option is to cut off the fuel, remove the carb bowls, and run the engine dry so it cannot fire when cranked.

    I personally would use the extra plug method. If you don't have extra plugs, you can use pieces of copper wire shoved into the caps and grounded to the block.

    Removing the battery or shutting off the master switch won't shut off the mags.

    Just thought of another simple method. Leave the mag switch in the off position and connect a set of jumper cables to the battery. Hook the negative cable to ground and touch the positive cable to the starter terminal. this will crank the engine and the mags will be off. You could also jump straight across both terminals of the starter solenoid if this is easier to get to. That will also crank the engine with the switch off.

    Bill.
      
    Report

  • Re: Compression check required per FAR 43 Appendix D

    by » 12 years ago

    Ok. Let me look into those last methods. I realize that you understand everything you said, but I didn't. I am new to maintenance, engines and stuff. I will locate the starter (don't laugh) and look at the wires. That seems to be the easiest idea.
      
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  • Re: Compression check required per FAR 43 Appendix D

    by » 12 years ago

    Jumping the starter would definitely be the simplest way. Your starter is probably on the back end of your engine unless you have an E gearbox, in which case it will be on the gearbox. In either case, You will see a single heavy wire hooked to the starter motor terminal. That is the positive lead. In most cases, if you hook a single jumper cable to the positive pole on the battery and touch the other end to the starter motor terminal, it will spin the starter with the mag switch in the off position.

    If the solenoid is easier to get to (it is probably on the firewall), there is a heavy wire attached to a terminal on each side of the solenoid. You can use a short piece of heavy wire or a jumper cable and jump straight from one side to the other of this solenoid and the engine will crank with the switch off. The solenoid is easy to spot. It is about an inch or two in diameter and an inch or two thick. A terminal on each side for the heavy positive starter wire and a smaller wire, usually attached with a spade connector, which goes to the starter switch. jump straight across those heavy wire terminals.

    Bill.
      
    Report
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