Cub guy lost here...

[melndav]

Hello all,
I am a new member to the group and to Taylorcrafts in general. We just finished our 7th Cub rebuild and have now gotten ahold of 2 pre-war T-crafts, a 40 BC and a 41 BL. I must say that construction wise the T-craft looks like a far sturdier airplane, but paperwork wise Piper has it beat hands down. Only one type certificate for all of the engine models, only 2 types of spars etc. I am happy that I found this group to help answer some of the questions. I've tried to research previous posts so forgive me if I repeat something already covered. So here goes...

1) can the Harer STC be used to bring a pre-war airplane to a BC-12D status (65hp), not just the 85hp version (I understand that it will have to be done under a 337 since it is a BL-65)?

2) if so can someone give me the major items that are included in this conversion, specifically I am curious as to wether it includes a change to the trim tab instead of the flippers?

3) Does anyone sell a set of blueprints for the airplane specifically the fuselage as I have some tubing damage to repair in the LH wing attach area.

4) last (for now) has anyone done a legal conversion from a BL-65 to an A-65 they would be willing to share their paperwork on for my field approval, or does an STC exist?


I appreciate your input (sorry for the long post) this is just for the BL-65. I think the BC is going to become a clipwing, but I suppose that is a whole other discussion in itself...

Thanks

David Mitchell

[Ragwing nut]

Re: Cub guy lost here...

Welcome to the site. As for your question regarding the conversion, nothing more than a 337 required for the Continental installation. MANY BL and BF models were converted right after the war. Any modification done prior to Oct '55 (I think my date is correct) is considered approved data. Forrest Barber might be able to help with the drawing.

Mike

[VictorBravo]

Re: Cub guy lost here...

You do not need the Harer STC to put the A-65 on the pre-war Taylorcrafts, since many of the pre-war Taylorcrafts had a 65 on them when built.

There is a factory service letter that is "approved data", which states that all BL, BF and BC models were identical firewall back, and that there were no differences other than the engines. So installing a Continental engine mount and engine on an originally Lycoming powered airplane SHOULD not require anything other than a quick paperwork shuffle.

If you want to get rid of the little trim flippers, you will have to install a post-war stabilizer, elevator and trim system, which will require a 337. The flippers are marginal and more than one pre-war airplane has had those flippers "repaired" so they work a little bigger... I mean better.

The Harer STC dows not address or alter the flipper trim system in any way. In my opinion, "don't open that closet, McGee!!". I am aware of one pre-war airplane where the owner wanted to install a larger engine and higher gross weight on a one-time 337, and the FAA would not allow the weight increase because the pre-war trim system was too ineffective.

If you are only wanting to put an A-65 on in place of a Lycoming 65, I'd leave the trim system out of it, I'd leave the Harer STC out of it, and just have a 337 done using the factory service letter as the basis of changing the engine.

The major items in the Harer STC conversion are:

Rebuilding the spar root fittings with thicker metal
Welding small rectangular plates onto the outer spar-strut fittings to join them into one piece fittings
Replacing the front spar root phenolic bushings with larger OD bushings

The minor differences include adding one or two wing tanks and plumbing, as well as adding additional fuel vent lines, and installing a larger diameter fuel line to the carburetor.

If you abide by the letter of the STC, you will HAVE to add the 85 engine, the wing tanks, and some of the other stuff.

The STC has several areas that are confusing, some discrepancies, and in some areas the STC raises more questions than it answers. There are no useful instructions or notes included with it. There is no explanation of why certain things are changed, or what the function of the parts is.

If you are doing a complete teardown on the aircraft, it will be fairly easy (and a really nice thing to do) to install the large spar bushings and weld the upgrades onto the fittings. It will allow future upgrade to an 85 engine without tearing everything apart, and the airplane will be worth a little more to your customer because he can upgrade it far more easily if he ever wants to. If you can find the wing tanks, put them in.

[crispy critter]

Re: Cub guy lost here...

Hello all,
I am a new member to the group and to Taylorcrafts in general. We just finished our 7th Cub rebuild and have now gotten ahold of 2 pre-war T-crafts, a 40 BC and a 41 BL. I must say that construction wise the T-craft looks like a far sturdier airplane, but paperwork wise Piper has it beat hands down. Only one type certificate for all of the engine models, only 2 types of spars etc. I am happy that I found this group to help answer some of the questions. I've tried to research previous posts so forgive me if I repeat something already covered. So here goes...

1) can the Harer STC be used to bring a pre-war airplane to a BC-12D status (65hp), not just the 85hp version (I understand that it will have to be done under a 337 since it is a BL-65)?

2) if so can someone give me the major items that are included in this conversion, specifically I am curious as to wether it includes a change to the trim tab instead of the flippers?

3) Does anyone sell a set of blueprints for the airplane specifically the fuselage as I have some tubing damage to repair in the LH wing attach area.

4) last (for now) has anyone done a legal conversion from a BL-65 to an A-65 they would be willing to share their paperwork on for my field approval, or does an STC exist?


I appreciate your input (sorry for the long post) this is just for the BL-65. I think the BC is going to become a clipwing, but I suppose that is a whole other discussion in itself...

Thanks

David Mitchell

David,
The engine as they said can be done by an IA with a simple 337 to the 65-75hp only,anymore hp will require the STC and some simple attach mods to the spar bushings,strut attach brakets,wing attach brakets,and fuel lines. The STC allows you to go from a BC12-D to BC12-D-85,Model 19,or F-19(85 -100hp with or without electrics). This is where you need to pay attention,if you just want to convert to an A-65 then no mods are required but if you ever want to use the STC then you must add ribs to each wing. The Pre-war birds have a 13 rib(truss built ribs)wing and the post war has 15 rib(stamped ribs) wings. In other woeds you have to have the 15 rib wings to be legal on the Harer STC because the 13 rib wings are only certified for 1100-1150lbs gross weight(I might be wrong about the exact wieght but I'm sure some of the pre-war boys can correct me here).The 15 rib(post war) wing was used all the way up through the F-19's and are still built the same way today.The only difference is in the size of bushings under the wing attach fittings and the strut attach fittings. On the F-19 they also added bushings under the butt end compression strut only where the BC12-D never had any at all. The original bushing size is 7/16" OD(1/4" ID) and they were replaced with 11/16" OD(1/4" ID).They also changed the original front butt attach fittings to .090 steel which is a little heavier than the original,the rear ones do not change. The Strut attach fittings that bolt onto the spars is originally 2 pieces and the STC calls for them to have a plate welded onto them to make them one piece(this has to be done on all four mounting points).
I hope this helps.Feel free to email or PM me if you need anything.

[VictorBravo]

Re: Cub guy lost here...

but if you ever want to use the STC then you must add ribs to each wing. The Pre-war birds have a 13 rib(truss built ribs)wing and the post war has 15 rib(stamped ribs) wings. In other woeds you have to have the 15 rib wings to be legal on the Harer STC because the 13 rib wings are only certified for 1100-1150lbs gross weight

The pre-war 13 rib wings were certified to 1100-1150 and the post-war 15 rib wings were certified to 1200 pounds... and the Harer STC re-certifies both of these type wings to 1500 pounds.

Kevin, unless I missed something while reading the STC, there is nothing anywhere in the STC that says "if you have 13 rib wings you cannot use this STC to 1500 pounds".

In fact, no less of an authority than C. R. Harer himself signed and stamped my STC, specifically referencing my pre-war serial number and pre-war model aircraft, to be eligible for the STC.

What gives you the idea that the number of wing ribs changes the applicability of the STC?

Melndav, the fact remains that a lightweight (less than 700 pounds if you can do it) pre-war Taylorcraft with a healthy Continental 65 is an excellent performer. On an 800+ pound airplane in hot weather with two big people, the 85 horse engine brings the performance back to what a light plane with one person would be.

[NC36061]

Re: Cub guy lost here...

The pre-war/post-war demarcation is a little misleading when talking about the 13 rib vs 15 rib wing. The 15 rib wing came into being with the increase in gross weight to 1200 lbs, which first happened with the 1941 Deluxe, hence the BC/BF/BL "12"-65 designation on those airplanes. I believe that both wings were used throughout 1941 as not all 41's were Deluxes, and had a lower gross weight, ie BC/BF/BL-65. All post-war production airplanes were 1200 lb gross using 15 rib wings only, hence the BC12D designation. I don't know any specifics about the STC's in question, but I would have to imagine that if gross weight is increased to or above 1200 lbs, the 15 rib wing would be a requirement; if gross weight is not affected, you should be able to use the 13 rib wing with less than 1200 lb gross weight. Hope this helps.

Dave

[melndav]

Re: Cub guy lost here...

Hi guys,

Thanks for the info as it has already answered some of my questions. I'm really only interested in upgrading to the 1200lb. gross so I can stay in the light sport category, but I do think doing the structural mods now is the thing to do for future engine changes. Do I have to change the fuselage attach fittings completely or modify the ones on the airplane? Also does anyone know where I can get a copy of the service letter that allows the change to the Continental engine? Thanks again

David

[VictorBravo]

Re: Cub guy lost here...

I don't know any specifics about the STC's in question,

The STC does not say anything one way or another about how many wing ribs are needed to fly at any given gross weight. Unless the STC sent to me was an incomplete package, the gross weight of my 13 rib pre-war BC-65 is 1500 pounds with the "model 19" version of the STC. That is "the specifics" of what the Supplemental Type Certificate says.

If the STC SHOULD have said one thing or another, or if it SHOULD have been limited to BC-12D's, or if it SHOULD have only been applicable to airplanes painted blue and white, then Gilberti and Harer forgot to do it. But that, alas is another topic.

[Ragwing nut]

Re: Cub guy lost here...

Hi guys,

Thanks for the info as it has already answered some of my questions. I'm really only interested in upgrading to the 1200lb. gross so I can stay in the light sport category, but I do think doing the structural mods now is the thing to do for future engine changes. Do I have to change the fuselage attach fittings completely or modify the ones on the airplane? Also does anyone know where I can get a copy of the service letter that allows the change to the Continental engine? Thanks again

David

There is a triangle gusset that needs to be welded on each wing attach point . If the wing to fuse attach brackets are welded together with a u shaped piece, no modification required to those. That is the minimum to bring to stock BC12-D standards structurally.

[crispy critter]

Re: Cub guy lost here...

The pre-war 13 rib wings were certified to 1100-1150 and the post-war 15 rib wings were certified to 1200 pounds... and the Harer STC re-certifies both of these type wings to 1500 pounds.

Kevin, unless I missed something while reading the STC, there is nothing anywhere in the STC that says "if you have 13 rib wings you cannot use this STC to 1500 pounds".

In fact, no less of an authority than C. R. Harer himself signed and stamped my STC, specifically referencing my pre-war serial number and pre-war model aircraft, to be eligible for the STC.

What gives you the idea that the number of wing ribs changes the applicability of the STC?

Melndav, the fact remains that a lightweight (less than 700 pounds if you can do it) pre-war Taylorcraft with a healthy Continental 65 is an excellent performer. On an 800+ pound airplane in hot weather with two big people, the 85 horse engine brings the performance back to what a light plane with one person would be.

Bill,
If you look at the STC I think you'll find the conversion is for the BC12-D to what ever. The "D" was giving to airplanes with 1200 or better gross.

David,
You can use the Harer STC to covert your bird to a BC12-D-85. This is an 85hp T-craft without electric using the short engine mount and it brings the gross wieght up to 1280lbs and still keeps you well within sport catagory. I have this approved also on a 337 to do the same mods and use an O200 on a short mount.

[3Dreaming]

Re: Cub guy lost here...

If you know anybody in your local FAA office have them pull up the records for N29815. This is a BL that had an engine change to a Continental back in the 40's or early 50's. This 337 can be used as approved data for the engine change. If that will not work I did one with a field approval 7-10 years ago. I can see if I can find a copy. If you have any questions give me a call. 618-393-2967 Tom

[Ragwing nut]

Re: Cub guy lost here...

Bill,
David,
You can use the Harer STC to covert your bird to a BC12-D-85. This is an 85hp T-craft without electric using the short engine mount and it brings the gross wieght up to 1280lbs and still keeps you well within sport catagory. I have this approved also on a 337 to do the same mods and use an O200 on a short mount.

I have done the same thing except with long mount and full electrics.

Mike

[melndav]

Re: Cub guy lost here...

Hi Guys,
I have another question for you. I got to looking at the one complete set of wings that I have that came with the BL. From what I have read here I think I have a real mixture, and I wanted to get your thoughts. I have 1 wing with a wing tank, 13 built up ribs, approx. 1/8 in. plates at the strut attach fitting, and the leading edge sheeting stops about 2" from the spar. The other wing has 10 built up ribs, 3 stamped ribs (although no sign of any spar damage or repair), no tank and the leading edge aluminum goes to the spar on the top. Intrestingly the front spar of this one has a small repair patch where it appears a hole was mis-drilled. Over the repair is a little stamped metal plate that says it is a taylorcraft factory repair. Anyway what have I got here??

[VictorBravo]

Re: Cub guy lost here...

Anyway what have I got here??

A typical mix 'n' match Taylorcraft

You have, in my opinion, two correct 13-rib pre-war wings, one of which has been repaired with three post-war ribs. As far as the size of the leading edge sheeting, that may have been done by a careless rebuilder some time ago. It will obviously look better if both wing sheeting is the same, but it will probably not fly any different.

[Winston L.]

Re: Cub guy lost here...

Prewar leading edges didn't go to the spar. If you measure the leading edge when it is flat they are normally only 12". Is there plates under the butt fittings?


Winston