Continental A-65 made into A-75-

[trez]

Please help with a basic question: If one was to upgraded the Continental from a A-65 Hp to a 75Hp, should there be an STC, log entry only or some other FAA documentation (besides W&B) to make the change "legal?"
I see in the TC that no provision is made for this change.
Appreciate any thoughts.
Doug

[Pearson]

Re: Continental A-65 made into A-75-

Doug,

Converting an A65 to an A75 is the easy part. I am not 100% sure, but I believe it only requires a log book entry. That, and doing all the mods to the engine, will get you an A75 engine. The problem comes when you try to install it on your airplane. Even if it is the original engine that came on your airplane, since it is now an A75, it is no longer legal to use on a Taylorcraft because it was never certified for use on that plane. You will need to get a one time STC from your local FSDO. I believe there is some documentation on the Foundation's website to help accomplish this. If not, send me an email to neat1s AT yahoo DOT com. Put "Taylorcraft" in the subject line, so it doesn't go to the spam folder.

This has been discussed on this forum a great deal in the past. If you do a search, I am sure you will find a lot of valuable info.

[Guest]

Re: Continental A-65 made into A-75-

Since its not in the TC then you will need one of these:
1) an STC that you purchased or developed on your own

2) FAA field approval (MIGHT be based on your data that you supply or data that you aquired for example by showing an existing 337 from after 1955 that you got from somone else).

3) 337 approval by you IA alone using an approved pre 1955 337 for the same alteration

Also you will need to file a 337 for each of the 3 metods even though I only specifically mentioned it on #3, that is becuase a feild approval and and STC both also require a 337 since they are major alterations.

I described the process.

I have no clue if for example you have data useable for a 65-75 conversion or if an STC exits and so on.

I also assume that you are talking about the airplane because you mentioned W&B and not the engine but you did not specifically say.

Dave

[Pearson]

Re: Continental A-65 made into A-75-

Here is a zip file that contains 5 scans of a 337 and correspondence that a friend of mine used to get his A75 legal.

[trez]

Re: Continental A-65 made into A-75-

Thank you all for the help, responses and the Zip file! Great reading.... I did finally find the thread on the conversion and installation as well- http://vb.taylorcraft.org/showthread...tal+conversion. What a tangled web this business can be.

[Mark Julicher]

Re: Continental A-65 made into A-75-

Barnstormer is a Designated Engineering Rep. for power plants. He can hook you up with legal data to do that installation for a reasonable fee.

[barnstmr]

Re: Continental A-65 made into A-75-

Trez,
I just now found your question... I'm sorry for not piping in sooner, but I have been away from the forum for a while. The guys have steered you in the right direction. I do have a couple of other items to add. First I am not sure if you were referring to getting the Engine modification approved or the airframe modification... so here are some comments for both.

ENGINE - You may have already found this, but Harry Fenton's website is the authority for the actual changes of the engine parts to convert an A65 to an A75. You will also want to know about the Continental Service Bulletins # M47-16 & M75-6R1. (I downloaded one but had trouble with the other... contact me direct by email and I will send you a copy).

AIRFRAME - Dave Rude has given you 3 options. But there is a 4th (337 with DER support) which is not as well understood by most. It is similar to a field approval, but it is not.

4) Submit a 337 with DER approved Data.

I have done a half-dozen or so DER Approvals like this to support A75 conversions for B-series Taylorcrafts, including NC22207, my father-in-law's '39 BC-65.

See my weblog post on this topic. "not all 337's are field approvals".

[barnstmr]

Re: Continental A-65 made into A-75-

Trez - Another issue to consider is which propeller are you planning to use. Your converted A75 will need a different propeller if you intend to eek out the extra horsepower because if you limit the RPM to 2300, you are at the exact same power as an A65. You only get the benefit of the additional power if you turn the engine faster (75 hp at 2600 rpm). So there can be two ways to get your A75 approved on a Tcraft.

1) A75 de-rated to 65 hp. (Uses the original A65 prop limited to 2300 rpm for all operations)

2) A75 rated up to 75 hp. (Uses a shorter prop and turns up to 2600 rpm).

This makes all the difference in performance. I have approved Taylorcrafts both ways, depending on the customer propeller preference.

[Guest]

Re: Continental A-65 made into A-75-

Trez,
I just now found your question... I'm sorry for not piping in sooner, but I have been away from the forum for a while. The guys have steered you in the right direction. I do have a couple of other items to add. First I am not sure if you were referring to getting the Engine modification approved or the airframe modification... so here are some comments for both.

ENGINE - You may have already found this, but Harry Fenton's website is the authority for the actual changes of the engine parts to convert an A65 to an A75. You will also want to know about the Continental Service Bulletins # M47-16 & M75-6R1. (I downloaded one but had trouble with the other... contact me direct by email and I will send you a copy).

AIRFRAME - Dave Rude has given you 3 options. But there is a 4th (337 with DER support) which is not as well understood by most. It is similar to a field approval, but it is not.

4) Submit a 337 with DER approved Data.

I have done a half-dozen or so DER Approvals like this to support A75 conversions for B-series Taylorcrafts, including NC22207, my father-in-law's '39 BC-65.

See my weblog post on this topic. "not all 337's are field approvals".

Hi Terry, yes! you are so correct and that 4th item you listed is one the methods mentioned in the old IA handbook.

I forgot all about it!

My bad and thanks for the reminder.

Dave