Wing trailing edge rubbing on flaps

[Awqward]

I have noticed that the top of my flaps is getting slightly worn in a few places due to contact with the wing trailing edge....presumably this is bad...I will get the flap rigging adjusted in my upcoming annual...has anyone come across this before?

[Guest]

This is quite common, the wing flap up stop screw may be too high. Many wings or wing flaps have chafe tapes to help prevent the wear.

Clarence

[Awqward]

Thanks Clarence, I have put some chafe tape in there for now....we don't have any rigging boards so I guess we'll just adjust the outboard stops a bit in the first instance....hopefully won't have to adjust the bell crank end as it looks like a pain to access...

[Awqward]

I'm almost afraid to ask what the spec is on any wear....in terms of depth of groove...

[FloridaMan]

I think people use Milar tape on it. 

[Piloto]

Thanks Clarence, I have put some chafe tape in there for now....we don't have any rigging boards so I guess we'll just adjust the outboard stops a bit in the first instance....hopefully won't have to adjust the bell crank end as it looks like a pain to access...

+1 on the chafing tape. Also check flaps hinge bolts. Excessive wear can cause play allowing the flap to raise in flight.

José

[bumper]

One of the best anti-chafe tapes is UHMW PE (ultra high molecular weight polyethylene), or UHMW for short. UHMW is tough as nails, one of the most mechanically strong plastics. It also has a very low coefficient of friction, almost as slick as Teflon, but much stronger. A 1" thick piece of UHMW will stop a .45 round (just not with me behind it). Tape is an almost translucent white that allows paint color to show through. Has acrylic adhesive, comes in various thicknesses from about 4 mils to over 10 mils - - get 4 to 6 mills is good for most applications as thicker, say 10 mil, will be too stiff to be very conformable. Note that even the thinner tape does not stretch much, so won't conform to compound curves without cutting.

 

Works on engine cowls, gear doors, wrap it around the bolts to tighten up the cowl flap hinges, etc.

 

http://www.amazon.com/TapeCase-423-3-UHMW-Tape-5yds/dp/B00823JBPW/ref=pd_sbs_indust_6?ie=UTF8&refRID=07M4CX95TSCZSK0KBBC7#product-description-iframe

[aaronk25]

Dont start adjusting the flap stop as it will kill speed....anti chafe tape first.

[jetdriven]

That stuff also degrades with uv exposure. Great for flaps or under the boot cowl but Aron's the gear doors it gets unsightly in a couple years.

[PT20J]

My '94 M20J has some rubbing, especially on the rivet heads. I thought about tape and researched various types but this seemed like a band-aid. And, since most of the rubbing is on the rivet heads, I was unsure how long the tape would hold up and how difficult it would be to periodically replace. My rivet damage is minor, but I saw an Ovation on the ramp the other day and it was so bad that nearly ALL the rivet heads on the top of the flap were worn down to about half their original thickness. I'm not even sure that was airworthy. 

Don Maxwell suggested an idea that I tried and it worked really well. Lower the flaps slightly. Put a wooden paint stirrer on top of the flap and use a stiff putty knife between the paint stirrer and the trailing edge of the wing to gently flex the wing skin upward deforming it very slightly. After carefully doing this along the length of the flap, I am now able to slide a piece of cardboard from the back of pad of paper between the flap and the wing trailing edge with the flaps up with only a slight drag on the cardboard as it passes the rivets. Before, I couldn't even slip a piece of paper between.

Before doing any of this, I checked the hinge play, rigging, flap stops and flap twist , and all were within spec.

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