Jump to content

Weird Flap Noise


Recommended Posts

Hello all, I'm new here!

On a KC-130T, after replacing filters on all systems on cycle, we noticed a weird noise on the upside while cycling the flaps. Flap movement is smooth at the motor AND the physical surface itself, and the T-Handle has been pushed in and verified with free movement of the nipple, but it makes a weird noise. It sounds almost like a trumpet and a pig squealing at the same time. Its only on the upside and it did it first at 40% flaps, then 30%, then 20% then stopped, then againt a 20% and it continues for a few seconds AFTER the flaps have stopped moving when doing a full cycle from 100% to 0%. This is will all engines running. Any ideas? Maybe the Surge dampener is going bad? but would it make a noise like this??

Link to comment
Share on other sites

It's either your rudder diverter valve, rudder pressure reducer or rudder pressure relief valve. Crawl up on the cargo door and listen to the squeal when the flaps go up. You can back the pressure reducer out about 1/4 turn and the squeal will go away or you can adjust the relief valve up a little. If either adjustment doesn't get rid of the squeal you may as well just replace the diverter valve...

Pull the flap control C/B and move the handle up and you will still hear the squeal, it's coming from your rudder diverter panel.

The squeal is usually caused when the relief valve and pressure reducer open within 100psi or so of eachother and the back pressure causes them to fight eachother

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...