Harer STC usage

[Guest]

Mr. Harer claims that with the wing mods you can make the GW you want at any value between 1280 and 1500 independent of the engine change.

I could have misunderstood him, I know that and I know there is a certain silliness regarding 1500 lbs and 65 hp so forget that part.

So forgetting the very high GW of 1500 and 65 hp because it is impractical and thinking of a GW a value like 1280 thru 1320 which make sense with a 65, has anyone used the STC in this way? to up GW with an 65 hp?

Looking for experiences and opinions.

Thanks, Dave.

[flyguy]

Re: Harer STC usage

I can give you a little initial info and someone can take it from there. I have the Harer STC for my 85HP Taylorcraft, but I have not used it. The information shows that with wing mods to the inboard mounts and reinforcing the outboard mount you can go up 80 lbs. To go higher requires reinforcing the fuselage. I haven't looked at the paperwork for a long time so this is from memory. Hope it is helpful. I'm sure someone who has installed the mods will chime in with info on their experience.
DC

[Guest]

Re: Harer STC usage

I can give you a little initial info and someone can take it from there. I have the Harer STC for my 85HP Taylorcraft, but I have not used it. The information shows that with wing mods to the inboard mounts and reinforcing the outboard mount you can go up 80 lbs. To go higher requires reinforcing the fuselage. I haven't looked at the paperwork for a long time so this is from memory. Hope it is helpful. I'm sure someone who has installed the mods will chime in with info on their experience.
DC

Darryl, thanks that makes sense and is helpful. 80 lbs is a nice increase too. Having not seen the STC recently I didn't recall that. Shamefully I had one too and threw it away years ago.

FAA/FSDO seems to agree that its ok to use STC to convert to model bc12d-85 (85 hp is on paper only) then remove the 85 and replace with 65 as per TCDS so you end up with a 1280 lb GW 65 hp. TCDS data is by default approved data so this thinking is more or less independent of the STC.

I think I like the scheme. Apparently one needs only to install the changes in drwings G108 thru G116 in to to this.

Thanks again, Dave.

[Pearson]

Re: Harer STC usage

I have the Harer STC for my project plane. According to the front page of the STC with all the fancy scroll writing and the FAA stamp at the bottom, this STC allows you 3, and only three choices. You can make your plane into a BC12D-85, OR you can make it into a BC12D-4-85, OR you can make it into a Model 19.

By looking at the Type Certificate Data Sheets for these three airplanes you can determine that if you choose to follow the STC to build a BC12D-85 you will be restricted to two possible gross weights; 1280 for a landplane, and 1351 for a sea plane. By looking at the TCDS for a BC12D-4-85 you can see that you will have the exact same gross weights. The TCDS for the Model 19 shows a utility category weight of 1380 and a normal category weight of 1500. No where in my STC paperwork does it show any way to get a gross weight of 1380 with either the BC12D-85 or the BC12D-4-85.

So, unless you are going to get a 337 to make your plane into a seaplane you are restricted to 1280lbs unless you do the full STC to Model 19 and get the 1500 lbs gross. As you may know, the only way to get the 1500 lb gross is to use the long engine mount in addition to the other mods.

[Frank DeBartolo]

Re: Harer STC usage

Richard,

The way I understand your explanation of the Harer STC is that the only way to increase the gross weight from 1200# is with the 85 HP engine--not with the 65 HP engine. In other words, if you keep the 65 HP engine, it does not matter what you do with the wing mods etc (the Harer STC) you still stay at 1200 max gross.

Frank D
N43684

[Guest]

Re: Harer STC usage

Are the wing mods just this:

11/16 butt bushings
15/32 strut bushings
.090" thick front spar fitting plates
.050 plates welded to bottom of strut fittings?

That's what I have speculated they are. All though I may have a dimension off a skeech.


My aircraft records say that changes on drawing g108 thru g116 where completed and I know I have at least the changes above to the wings.

Is that all there is to the wing mods?

[Pearson]

Re: Harer STC usage

Frank,

I am not an aviation lawyer, but from my interpretation of the STC you are correct. If you keep the A-65 engine you will have stronger wings, but you are still legally restricted to 1200 lbs, since you did not comply with the STC by intalling the C85. If you are restoring your plane and want to have peace of mind in knowing you have the beefier fittings in the wing, that would be a great time to install them. You can alway put the C-85 engine on later. Makes a nice way to spread the extra cost out.

[crispy critter]

Re: Harer STC usage

I don't know if this will help but I spent 2 very long years getting approval for Crispy Critter becaue I wanted to put the 0200 on a short mount. The engine approval was easy but I also got approval to ad the light weight Sky Tech or B&C starter and the short light weight B&C alternator(the PMA'ed one)later if I choose too,notice I said "LATER",there is a reason for this and the light weight electrics are for now a ONE TIME DEAL....later. I was also trying to get the gross increased to 1320lbs. I had to go back and completely redo the wing attachments and a few other mods(all straight off the factory drawings for the F-19) in hopes of getting the 1320 GW approved.This was all recommended by the FAA and FSDO that I was working with,they said if I done this they think they could approve it......but they didn't....yet. They did tell me not to give up. Once Crispy is flying I have to log a series of test flights and manuvers that are listed by them and record the results,send copies to the FSDO and FAA all as part of my attempt to get an approved STC so anyone can do this mod. They also told me that after these flights had been successfully completed and all data had been satisfied they would send someone out to inspect the airplane as part of the STC process,also probably fly the airplane with me so they can themselves have proof of the assigned manuvers and then if no problems were found we could increase start the the paper work for the gross weight to 1320lbs and hopefully get approval for the STC at the same time. Everyone keep your fingers crossed....Crispy should fly in a couple weeks if all goes well.

[Guest]

Re: Harer STC usage

Update for those interested.

Well it seems as though the operation was a success.

I got the Harer STC and used it on my 65 hp BC12D to raise the GW to 1280 lbs with the wings mods of course.

Made out the 337's and sent them in over a week ago. No gripe so I guess I did it correctly, or the PMI is on vacation.

Actually had discussed it with him a month ago so I expected it to be ok.

Dave.

[VictorBravo]

Re: Harer STC usage

If you are using a very strict reading of the STC, you may find that you are forced to add one or two wing tanks, which is a big pain in the ass.

While doing the wing tanks and looking at the drawings, you also may find that you are forced to put the wing tank fuel shutoff valve someplace where it SHOULD NOT BE, Mr. Gilberti, and where they psose un-necessary flight safety hazards.

Not to bring up any old battles, but there is also a huge question of whether or not you have to add a paper thin 1/32" thick plywood doubler to the spars out at the strut attach.

This is why my personal recommendation for someone contemplating this project is to do your own 337 or field approval which is the sensible parts of the Harer STC with three or four deviations. This may not apply to you if you have already bought and signed off on the STC.

Are the wing mods just this:

11/16 butt bushings
15/32 strut bushings
.090" thick front spar fitting plates
.050 plates welded to bottom of strut fittings?

That's what I have speculated they are. All though I may have a dimension off a skeech.


My aircraft records say that changes on drawing g108 thru g116 where completed and I know I have at least the changes above to the wings.

Is that all there is to the wing mods?