Cessna flaps

Discussion in 'Maintenance Bay' started by motoadve, Jul 13, 2018.

  1. motoadve

    motoadve Pre-Flight

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    So flaps stopped working, called my mechanic , and he said to check the rubber roller in the flap motor, it was stuck.

    Moved it by hand got it un stuck and flaps work fine now.

    Has anyone have this happened with their Cessna?
    The fix was to easy and cheap to make me confident.

    According to my mechanic probable a tall passenger bump the area below the flap lever and hit the switch.(I did have a tall passenger 2 days ago).
    Is this theory ok?

    What caused this if it was bumped what happened?
     
  2. Dan Thomas

    Dan Thomas En-Route

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    The system is out of rig. There is a microswitch to stop the motor at both ends of the flap travel, and if your up-stop switch isn't set right it can allow the motor to drive the flap up hard against the ends of the slots in the tracks, or bottom the jackscrew nut against the jackscrew shoulder, either of which can jam the motor. The switch needs adjusting, and perhaps the right flap pushrod as well, since it will allow the screw-jamming if it's set too long. Rigging isn't a simple job, and the service manual is a must for getting it right.
     
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  3. James331

    James331 Touchdown! Greaser!

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    I have manual flaps, not saying electronic flaps are bad, if your into that sort of thing.
     
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  4. JDACO

    JDACO Pre-Flight

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    There is a roller rebuild kit you can buy from Spruce. Cheap and easy to fix.
     
  5. Dan Thomas

    Dan Thomas En-Route

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    It won't fix a misrigged flap system.
     
  6. JDACO

    JDACO Pre-Flight

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    Thats right! They would need rigging as well as the re-build kit.
     
  7. thomasdr72

    thomasdr72 Pre-takeoff checklist

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    When is the last time the flap actuator was removed, cleaned and the gearbox in the jackscrew regreased? That would be my first goto, we didn't have any issues, but the grease was dried out when I took it out and inspected ours about a year ago.
     
  8. Dan Thomas

    Dan Thomas En-Route

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    There's another problem. There are three different actuators used on 172s alone, depending on vintage and whatever service bulletins have been complied with. The greased actuators have not been used since the mid/late-60s, but I used to find the later models all greased up and not working right. The earlier units were a simple screw/nut affair, and grease worked ok. Had to use the right grease, though. The later models are ballscrew-type actuators, and grease gums up the recirculating-ball mechanism so that they don't travel and the thing will stick and wear out faster. It's supposed to get a tiny amount of non-detergent SAE 10 straight mineral oil. Guys got used to greasing these things and they just keep doing it 50 years later. Too many guys don't read the service manuals, and flap problems abound. The manuals tell you how to figure out what needs what. Manuals aren't cheap, but having to fix mistakes with new parts and the labor to install them costs a LOT more.