Flap Handle

[mhcrowder]

Ok, We've now been flying for about 1 year in our Highlander. Overall we're extremely pleased with it's performance. It's a little on the heavy side but it's performance has met our requirements. My build partner and I took transition training with Vic Payne in Brasstown, NC and this was time well spent.

One of the issues we've had is that the flaps will sometimes jump out of their notch. We've had it jump from 3 notches to 1 notch on short final over trees that induced quite a pucker factor and quick reaction. Our normal approach was to slow on downwind, and at 70 MPH (indicated) pull two notches of flaps and continue slowing to 60 MPH (indicated) and fly the rest of the approach at 60 MPH. Our tested stall speed with 2 notches of flaps is between 43-51 MPH (depending on weight ) and with 3 notches of flaps is between 41-50 MPH.

We called the factory and they indicated that flaps should be deployed at 60-50-40 MPH for 1-2-3 notches of flaps. As you can see, we can't get to 40 MPH. They think that we are just going too fast on final. We still don't think the flaps should notch jump, even if we do get a little fast.

Reading the Forum I know this has been an ongoing battle. I even see that that there was an "incident" at Airventure with this issue.

We are aware of Plane Fun's Ratcheting Flap replacement, but prefer not to add the additional weight if we can avoid it. Has anyone tweaked the design? Improved the design? Pictures please? We're down for our Conditional Inspection now and really would like to work on this issue.

Thoughts?

Michael Crowder and Ed Bodette
Highlander N371EM

[SheepdogRD]

Check this post out and see if it helps: https://www.wingsforum.com/viewtopic.php?p=43720#p43720

[danerazz]

Surprised your stall speed sounds a bit fast.

What seems to happen is the outer handle tube flexes as you apply force, and it binds on the inner tube (button), causing the latch bolt that holds the flaps in position to not engage in the notch.

Slowing as much as possible helps, as does pulling up with a grip as close to the pivot (base) as possible.

There are other modifications that help, from a newer design flap handle from Plane Fun Aircraft (Billy Payne), putting a knob on the end of the button so you can pull it into engagement, complete redesign of the handle to make a stiffer handle and less-binding button.

Otherwise, the flaps popping out of position keeps you on your toes.

[mhcrowder]

Thanks Dane, I'll probably start a 2nd tread on the Stall Speed to keep it separate...

We are making a few changes. We didn't want to go with Plane Fun Flap Handle due to it's increased weight. We are trying a few suggestions found in previous posts on this forum and suggestions from the Facebook group.

1. Change the profile near/at the top) to allow it to enter the 3rd notch easier (Tyler Payne suggestion)
2. Deepened the notches a millimeter or two (Frank Mann suggestion)
3. Added a strengthening piece to the outside tube for strength (

Hope to have the mods done soon so we shall see.

Michael Crowder and Ed Bodette
Highlander N371EM

[Tralika]

Enlarging the openings on the two aluminum plates that the bolt on the flap handle engages and replacing the coil spring in the flap handle will fix the problem. The factory supplied spring is 1 1/4" long x 3/8" in diameter and is made from .040 wire. I found a spring of the same dimensions made with .060 wire at Ace Hardware. The flap handle flexes under the aerodynamic loads in flight. The spring provides more compression to force the bolt on the flap handle into the openings on the two aluminum flap plates. I hogged out at least 1/8 of an inch of material on all sides of the openings on the flap plates with a Dremel tool. It took me about three tries to get the openings large enough to make it work smoothly. That involved dissembling and reassembling the flap handle then test flying it each time. I could have saved a bunch of time by taking out more material from the flap plates on the first try. Be sure to round off the little points on each of the three openings on the flap plates. The points were galling causing even more friction against the bolt.

[Tralika]

This is not a great photo but you should be able to see about how much material I had to hog out of the flap plates to make the system work smoothy and not slip out of position in flight.