My 180 has a stock wing-- no leading edge cuff, no fancy tips, no VG's-- except for having been fit with flap gap seals sometime in the dim past. Whoever did it never bothered to do a logbook entry, let alone a 337, and I hate loose ends, so I need to either document it or remove it. Pro's and con's?

Unless speed is a higher priority than low speed handling characteristics, you might want to remove them. I'm not sure how much you gain on the top end, but I do know that the airflow over the flaps leading edge stays attached better during flap deflection with the stock cove contour.

I'm no expert, but I have quite a few hours in my 180 that came with flap gap seals.

I've thought about taking them off, but honestly, I can land just as slow and short as any other 180 with similar mods, and they do help with rate of climb, which is at least as important. Not saying I'd put them on if I didn't have them, but in my experience the downsides tend to be exaggerated on the Internet.

My thoughts are based on a brief glance at how the seals change the wing contours and my understanding of theoretical aerodynamics rather than a great deal of practical experience. Theory and reality align perfectly in some cases and seem completely at odds in other cases. I have made one landing in a 1956 180 with flap gap seals installed and I did manage to land it pretty short. Guess it's a question of what does it buy you and what does it cost you. Basing your decision on any anecdotal account is unreliable.

If you have flap gap seals i would bet you have aileron gap seals as well? The aileron ones are less obvious for sure.

Im not sure who else makes them but most are knots 2 U. SA2382NM http://www.knots2u.net/cessna-flap-gap- ... dels-cfgs/

For what its worth i flew my TD 172 for years with them and it was a fine BC plane but it came with gap seals so i would not know any difference.

You may order the CD from the FAA if you haven't already. Some times it comes with a title search. Its only $7 and a 337 may have been filed in the past and just lost... It can be worth the money when replacement STC;s are so expensive.

Oregon180 wrote:...in my experience the downsides tend to be exaggerated on the Internet.

Ditto. I could not tell the difference on a 182 except for a solid speed increase when they put them on a rental I used to fly, landing short or normally. There probably were real differences, and many claim landing short is affected, but it wasn't enough for me to notice or care about.

My only experiences on airframes with and without them is on various cubs, mostly the CC ones. Personally, doesn't matter to me either way. If they're on, I'll leave them on. If they're not, I won't install them. Wash either way.

I flew my Hot Rodded 61 185 for 20 years. Loved going back country exploring with it. Was hoping for alittle more top end. Got some, maybe 2-3 mph. But the low end really sucked.. Took them off as soon as I could.I have a buddy who has a set on his older 182 that i have been trying to talk him into taking them off. He's never flown with them off,so he doesn't know what it should feel like on the low end. He does fine so he'll probably just keep them on. Mike

Flew a C150 that they ruined. No exaggeration. Operations in a high DA area.

Flap gap seals somewhat defeat the effectiveness of the semi fowler flap design on the Cessna flaps. My 170 had them, then they painted it......so to remove them would have meant repainting at least the flap coves......

I did not like them on that airplane, or on two other airplanes I've flown with them.

Huge differences??? No....but there is a difference, and if you're actually interested in slowing down on final, they make a significant difference.

I'd take em off, barring having to repaint the plane.

But, if it has aileron seals, those I'd leave on.

MTV

I knew I should have done at least one of my earlier posts on this into a Word.Doc

I tried to search here but only got the latest posts.

Maybe Zzzz or someone else can do a better search

I now have vision problems here so will keep it short.

Take them off.

I have done the test before and after. How short you can land is not the question.
The question is how much rate of descent can you get.

My 170 "with all the mods" could barely make 400 - 450 feet per minute descent rate
when I needed at least 600 - which it did before the flap gap seals.

Fortunately I did the Idaho testing at Donnely and landmark instead of some short shit.

Just recently sold it, and I hear that the flap gap seals are still wrapped up in the old flannel sheet.
I was also luck that I did not put on the Horton set that came with the plane.
This advise came from someone close inside H.

My mechanic told me to do the Knots-2 U -- which I did. They come off with fifty some screws
instead of having to drill them off.


Nuff for now

PAMR MX wrote:If you have flap gap seals i would bet you have aileron gap seals as well? The aileron ones are less obvious for sure. Im not sure who else makes them but most are knots 2 U. SA2382NM http://www.knots2u.net/cessna-flap-gap- ... /......You may order the CD from the FAA if you haven't already..... a 337 may have been filed in the past and just lost... .

No aileron seals.

These flap seals are probably Horton. Knots-2-U makes a big deal of theirs attaching with screws, mine are cherry-maxed.

Got the CD from the FAA, no 337 for the gap seals. Searched the logbooks, no logbook entry either.

Googled up a discussion on BCP from a couple years ago about removing flap gap seals. It mentioned structural rivets going into the spar...my gap seals appear to be riveted to the flap cove metal just aft of the spar. About 50 cherry-maxes per side to remove, not counting the brackets which are also riveted on. It looks like the seals were installed after the airframe was last painted, with the seals pre-painted to match, so removing them would not leave big mis-matched areas exposed.

Regarding un-reliable anecdotal advice....point taken. Unfortunately when you haven't personally flown a certain model airplane both with and without a certain modification, you don't have too much else to go by. I bit the bullet & installed a set of VG's on my last airplane (C150/150TD) after hearing everything from "they didn't do anything" to "they make a completely different airplane out of it" from others who'd installed them on a C150. After installing them, I wouldn't say they didn't do anything but the differences in stall speed and aileron effectiveness was very subtle. I don't think I'd spend the money to install them on a stock Cessna wing again. But just today I was talking to a friend of mine who has VG's on his otherwise stock-winged 170B, and he says they really improved the low-speed ailerons. So who knows?

I'll add my own anecdotal info, FWIW. My P172D had the Madras droopy tips which are so obvious when I bought her. Otherwise the wing has the stock airfoil common to all pre-1973 172s, with no leading edge cuff of any kind. Those droopy tips tend to add drag, albeit they also add some low speed controllability. Hoping for some added speed to make up for that drag, I had Knots-2-U flap gap seals installed, about a year and a half or so after purchase. So I had about 100-125 hours in this airplane without them, and I've got over 600 hours since then.

The flap gap seals add measurable cruise airspeed, about 4-5 knots. There's no doubt about that. It's probably the least expensive and most successful "speed mod" for 172s, and I'm assuming similarly for other model Cessnas. A good bang for the buck.

As for any other effect, I honestly cannot tell that there was any change. I have many hundreds of hours in other 172s, also, and they all fly similarly, some nicer than others. But with 40 flaps hanging out, the only difference between mine and others comes from the droopy wing tips, not the flap gap seals, that little bit of low speed controllability I mentioned. I have flown relatively slow final approach legs most of my flying life, and I just can't tell the difference between with and without my airplane's flap gap seals.

Whether you would notice any measurable difference in your 180 if you yanked your flap gap seals, I can't say. But if you're satisfied with your airplane's performance now, why muck with it?

Cary

I have a 1975 172m with the stock cuffed wing. When I bought the plane it had flap gap seals, aileron gaps seals and stall fences installed. Some people talked me into removing the flap gap seals to get better take off and landing characteristics. When removed the only thing that happened was I lost 150ft/min climb rate and the slow flight handling was not as good. I then went and installed the knots2u flap gap seals to see if it was just my imagination about the 150ft/min. I bolted them on and the climb was right back up there, took them off and immediate loss of climb and the real low speed handling is not as nice. They are staying on the plane while I own it.

NO flap gap seals for me ! I wouldn't pay the mail / UPS charges to get any .KILLS 20% of your lift on takeoff -lengthens take off run . If Cessna thought they would make airplane faster or better they would have added them at factory .Aileron gap seals are different story -Have those to work with my SPORTSMAN STOL !

182 STOL driver wrote:NO flap gap seals for me ! I wouldn't pay the mail / UPS charges to get any .KILLS 20% of your lift on takeoff -lengthens take off run . If Cessna thought they would make airplane faster or better they would have added them at factory .Aileron gap seals are different story -Have those to work with my SPORTSMAN STOL !

This is interesting, I have left mine on because I have heard that they improve takeoff and climb. With the O-300, I need all the climb performance I can get. Are you pretty confident that they actualy hurt the performance?

182 STOL driver wrote:NO flap gap seals for me ! I wouldn't pay the mail / UPS charges to get any .KILLS 20% of your lift on takeoff -lengthens take off run . If Cessna thought they would make airplane faster or better they would have added them at factory .Aileron gap seals are different story -Have those to work with my SPORTSMAN STOL !

This is interesting, I have left mine on because I have heard that they improve takeoff and climb. With the O-300, I need all the climb performance I can get. Are you pretty confident that they actualy hurt the performance?

Interesting feedback on the flap-gap seals....some adamantly pro, some adamantly con, and still others sort of indifferent.

182 STOL driver wrote:NO flap gap seals for me ! I wouldn't pay the mail / UPS charges to get any .KILLS 20% of your lift on takeoff -lengthens take off run . If Cessna thought they would make airplane faster or better they would have added them at factory .Aileron gap seals are different story -Have those to work with my SPORTSMAN STOL !

Very interesting post. Where do you get the 20% figure from. In the post above yours we have a guy who repeatedly took them on and off for comparison and every time got better numbers with them on.
I enjoy these type of threads, seems to be one of the topics where engineering and real world don't line up very well.

Cary wrote:.......Whether you would notice any measurable difference in your 180 if you yanked your flap gap seals, I can't say. But if you're satisfied with your airplane's performance now, why muck with it?

Because I can.
If "good enough" really was good enough, we'd still all be flying 65 horse Champs & Cubs-- and there'd be no 180's with the ponk 520, 185's with the 550, stol cuffs, VG's, or any other mods intended to improve performance..