Thanks Thanks:  0
Results 1 to 7 of 7

Thread: Main Circuit Breaker Popping

  1. #1
    JWE's Avatar
    Join Date
    Jan 2018
    Location
    NC
    Posts
    148
    Post Thanks / Like

    Main Circuit Breaker Popping

    The main alternator CB (50 amp) on our aircraft is popping intermittently. No other CBs popping. Checked the engine monitor. Volts steady at 14.4 but amps jumping very erratically between about 17 and 26 amps. Had the radios, strobes, and LED wig-wag lights on. Had a new 50 amp CB installed a little over a year ago. This problem just started recently. It's on a Husky Lycoming 0-360. Any thoughts?

  2. #2
    wireweinie's Avatar
    Join Date
    Aug 2013
    Location
    Palmer, AK
    Posts
    3,976
    Post Thanks / Like
    What charging system? Is the ammeter located in the bus feed or in the alternator output lead? Is the noise in the headset when the ammeter moves between 17 and 26 amps? Also, 17 amps is a huge amount of current, is that a typical reading during normal ops? Is that reading during battery recharge such as right after startup?

    Web
    Life's tough . . . wear a cup.

  3. #3
    wireweinie's Avatar
    Join Date
    Aug 2013
    Location
    Palmer, AK
    Posts
    3,976
    Post Thanks / Like
    While the engine is running, watch for steady voltage and erratic amps, then pull one circuit breaker at a time (not the alternator output or field breaker) and watch for a change in the amp flow. Specifically you are looking for the erratic amp reading to steady down. When it does, the problem may lie with the circuit powered by the last breaker pulled.

    Web
    Life's tough . . . wear a cup.
    Likes BC12D-4-85 liked this post

  4. #4
    JWE's Avatar
    Join Date
    Jan 2018
    Location
    NC
    Posts
    148
    Post Thanks / Like
    Turns out my question was premature since another problem has presented itself which will most likely require an engine teardown. So we'll have to wait until that problem is solved before chasing this one. Thanks for the replies though, Wireweinie. I'll revisit this one later...

  5. #5
    wireweinie's Avatar
    Join Date
    Aug 2013
    Location
    Palmer, AK
    Posts
    3,976
    Post Thanks / Like
    Let us know.

    Web
    Life's tough . . . wear a cup.

  6. #6
    Seaworthy's Avatar
    Join Date
    Feb 2005
    Location
    Massachusetts
    Posts
    1,559
    Post Thanks / Like
    Quote Originally Posted by JWE View Post
    Turns out my question was premature since another problem has presented itself which will most likely require an engine teardown. So we'll have to wait until that problem is solved before chasing this one. Thanks for the replies though, Wireweinie. I'll revisit this one later...

    While you have the engine out-- look for an intermittent short in a line that would normally carry high amperage ie from the battery, starter etc. Wire going through/ around where it may have a chafe and an intermittent ground. Pulling that many amps you could look for scorching/ burning. A dead short wouldn't allow you to reset breaker. That's something that is a must find. Once had an internally shorted reverse current relay in a helicopter--- chased wires forever and finally figured that, "this is the only thing it could be"--and it was.
    Marine Corps Aviation since 1966

  7. #7
    JWE's Avatar
    Join Date
    Jan 2018
    Location
    NC
    Posts
    148
    Post Thanks / Like
    Thank, Seaworthy. We'll check for shorts and scorched lines.

Similar Threads

  1. Popping sound.
    By n40ff in forum Cafe Supercub
    Replies: 24
    Last Post: 05-26-2019, 04:36 PM
  2. Replies: 27
    Last Post: 05-28-2014, 12:35 AM
  3. Circuit breaker question
    By Richgj3 in forum Cafe Supercub
    Replies: 1
    Last Post: 11-17-2011, 11:51 AM
  4. Circuit breaker polarity
    By Gordon Misch in forum Super Cub Sick Bay
    Replies: 2
    Last Post: 10-23-2010, 10:38 PM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •