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**Jim Herpst** · 02-21-2006, 16:25

Re: 85 HP Engine

Lee,
Gosh, I almost got tired thinking about all the discussion thats on this forum already on all your questions. Seriously. If you do a search .....actually several searches with the key words you asked about you will find volumes ands many with pictures (thanks to Mr Lees and CO !) Its all here and only key strokes away Lee. I swear !!!! Best of luck. The 85 upgrade is the way to go.....

**Yellow Duck** · 02-21-2006, 17:35

Re: 85 HP Engine

Thanks Jim, had not though about the search bit. Nice to know.

**crispy critter** · 02-21-2006, 18:04

Re: 85 HP Engine

Lee,
I have also seen some BC12D-85's without the sheer plate on the strut fittings but as you already know I spent almost a year with Crispy Critter on hold trying to get this approved through factory drawings,stc's, or 337's with no luck!!! The factory says, as do the type certificates that the mods have to be done the same as on the 19,model 19, and F-19. The only thing that doesn't change in the size of the baggage compartment and the engine mount & cowlings. The fuel lines have to go up from 1/4" to 5/16", a minimum of 18 gallons of fuel, 11/16"OD bushings at the butt end of both front main spars,.090 thick butt fittings, sheer plate on all 4 strut fittings, and a F*!#ing partriage in a pear tree!! Sorry, it makes me mad just talking about it because of all who told me I could get approval with no mods(just paper work) and it cost me a year and then a bunch of rework on my wings that were ready to paint and I had to cut it all off and start from scratch.

**VictorBravo** · 02-21-2006, 20:53

Re: 85 HP Engine

The real benefit is that you have to take a good look at the spars and fittings for the first time in 60 years...

**flyguy** · 02-21-2006, 20:53

Re: 85 HP Engine

Yeah Kevin,
That really is a bunch of crap. MY 85 was signed off on a 337 and has been flying with only the fuel tank changes for years and years. It flys just fine, and nothing is coming loose. Of course I haven't been doing aerobatics, except for spins, and haven't flown thru any thunderstorms or such. LOL. I am limited to 1200 lbs, which is full tanks, me, and perhaps a smallish mouse! (40 baggage actually.) I've seen junk on new production aircraft that I wouldn't put on my old 73 SUV, and yet they turn around and get all squirrely about really piddly stuff on the old aircraft.
Darryl

**mulwyk** · 02-21-2006, 21:27

Re: 85 HP Engine

Darryl:
I've noticed that half (or more) of the discussion on our T-Craft discussion forum is about the 337, STC, PMA, FAA, IA, BS. Not what works, or what's safe, not even about flying 'em. No, it's mostly how to deal with the paperwork! AAARGH!

Bob Gustafson

**matsuthunder200** · 02-21-2006, 22:24

Re: 85 HP Engine

Lee
A good frind of mine is puting a 85 hp motor in his t-crft. it has a 75 hp in it now. He has been in contact with the faa about 10 times now here in Alaska And in Oklahoma. He finaly found out that there is no way to get a 337 approved on a motor swap unless it is 10% hp or less than the one taken out.
All other motors haft to have a stc. I have about 15 337s on my plane . im just glad that they were all done before the faa got strict with there rules.

**Dano"T"** · 02-22-2006, 07:09

Re: 85 HP Engine

I have a letter from the FAA Engineering office dated 1974 that I found in the T-craft we just bought. The letter is in reference to wipline floats inc. filing an aplication for an STC for an 85HP upgrade on a BC12D with no gross weight increase. The letter reads in summation that they reviewed the data and studied STC SA1-210 (Gilbertti/Harer) and concluded that a new STC is not required and that by completing only the fuel mods and omitting the wing mods this will be approved. "In other words, it is considered acceptable from an engineering standpoint to incorporate the fuel system porton of STC SA1-210 along with the C85 engine and omit the wing mods for an aircraft gross weight of 1200 lbs." Quoted from the letter. Another quote reads "In View of the above, we do not consider another STC to be required and suggest that the aircraft be returned to service by referencing STC SAI-210 as the approval basis and itemizing only those portions incorporated. A limitation should be noted; however, that the gross weight of the airplane remains at 1200lbs." signed by Keith Anderson Chief, Engineering and Manufacturing Branch AGL-210 FAA. This letter is accompanied by approved 337 referencing SAI-210 "with no gross weight increase"

I understand that this is from 1974...but they in essence, are saying that the HP upgrade can be done under STC SAI-210 with out the gross weight increase mods. So does this letter mean STC SAI-210 covers this....and we, are all spinning our wheels. Mr. Harer would have checks rolling in so fast it would make his head spin if this is so. I believe that the wing mods have NOTHING to do with the HP increase and everything to do with gross weight increase.

So, does this documentation that I posses Help anything? I don't know...but there'd be a happy tribe if we were allowed to do this.

**dewhitaker** · 02-22-2006, 10:39

Re: 85 HP Engine

Wow Dano that sounds like a real find! I agree with everything you've said. Would it be possible to post that letter on the Foundation Technical link? Maybe if more copies of that letter existed it would sway things in our favor for the guys who want to go to 85 HP?

**VictorBravo** · 02-22-2006, 12:28

Re: 85 HP Engine

Dano, you can put that letter up on ebay and probably retire

Or, you could have it posted on the T-craft club website

I do stand by me previous statement that it is a good idea for someone to have an excuse to check the spar roots and fittings after 60 years. Take a look at Rob Lees' website and the pictures of his wing attach fittings removed from G-BREY before making new fittings. We're talking life and death here, and I do believe that anyone putting a bigger engine on a Taylorcraft needs to know what condition his spars and fittings are in. If the plane's just been restored, then no problem. But buying a long-neglected airplane sitting out behind the barn, dusting it off, and bolting an 85 on the front is not a good idea IMHO.

**Robert Lees** · 02-22-2006, 14:01

Re: 85 HP Engine

Further to Bill's comments, the photos of my "defective" spar fitting is below. This is the rear spar fitting, so perhaps not as critical as the front. Needless to say, I inspected the other three spar butts too! (they were OK).

Obvously the mechanic/owner/"person unknown" who last looked at it (in the late eighties) just put in a reinforcing plate to cover the problem.

A pity they didn't investigate further...the spar butt underneath the delaminating ply looked like this:

Perhaps not a "life-and-death" scenario...the rot was of greater concern than the split. I was very fortunate to have the expertise of a very well respected structural aeronautical engineer who came up with a repair scheme that was approved by the UK authorities.
Caveat emptor

Further to Dano's revelation, we have a BC12D operating here at 1200lb with a C-85...approved on the basis of an American 337! I have tentative approval to install an 0-200 on the same basis, although I have yet to fund a replacement engine!

Rob

**Dano"T"** · 02-22-2006, 14:43

Re: 85 HP Engine

I'm not sure the FAA will see this as such a revelation...but it is an interesting document nontheless. I hope it helps change minds, but I fear that the ol' 10% HP rule will come to haunt. Unless the STC'd fuel mods ARE the only really necessary mods for this increrase in the eyes of those in power and if they use this as basis to allow a blanket ruling under the STC SAI-210 then great....I, for one will not hold my breath....mamma said it's bad for me. It may be good for Taylorcraft though.

**matsuthunder200** · 02-22-2006, 21:03

Re: 85 HP Engine

Dan
I have had done what your letter says or about that.
First i had the 90 hp motor upgrade done. It was approved with the 1200 lb grose wt. Then about a year later I had the 1500lb wt increse done.
Both was approved with a 337. I do have copys if it would help anyone.
On one 337, i think it says something about referencing the gilbertty stc. I also have a frend that got his 1500 lb wt increse with a 337 10 years after having a 85 hp installed in his t-craft with the 1200 lb gr,wt. Both was a 337.

**taylorcraftbc65** · 02-23-2006, 12:21

Re: 85 HP Engine

Robert,
Thanks a million for the photo. I load these and have a file FULL of your tech photos, they are a gold mine of information. BRIE

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