BC12-D A65 to A75 Conversion

[flybikefarm]

Re: BC12-D A65 to A75 Conversion

Go here check note 7.




http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/f67f14de69fae5c38525670e00450a67/$FILE/E-205.pdf

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

Charles,
Looks like you figured it out. The SB I listed pretty much lets you convert any engine of the same model to a different modification level, or "dash number". Provided you use the correct parts for the change.
Make the correct log entry and let's go flying.
EO

[Pearson]

Re: BC12-D A65 to A75 Conversion

I went to the FAA website above and downloaded a copy of the Type Certificate Data Sheet (TCDS) for the Continental A65 engine. Very interesting reading, especially "note 7" referenced above. It reads, "NOTE 7. Model A-65-14 differs from A-65-8 only in that it incorporates special pistons, rocker arms and exhaust valves, seats and guides.".

So now I am wondering, since there appears to be a way to get 75 hp out of an A65 without having to jump through the hoops associated with converting to an A75, what kind of pistons, rocker arms, and exhaust valves are used to convert an A65 to a -14 with 75 HP?

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

Richard,
I'm working with out a net here, but if my feeble memory serves it has the stellite faced valves, waffled underside of the piston and lube holes in the intake rockers for oil cooling the springs. If someone has the parts manual handy they should be able to compare part numbers.
EO

[Ragwing nut]

Re: BC12-D A65 to A75 Conversion

Richard,
I'm working with out a net here, but if my feeble memory serves it has the stellite faced valves, waffled underside of the piston and lube holes in the intake rockers for oil cooling the springs. If someone has the parts manual handy they should be able to compare part numbers.
EO

Also drilled connecting rods for A75. I still do not know what changes are made to make one a -14.

[Pearson]

Re: BC12-D A65 to A75 Conversion

Mike,

I thought the TCDS pretty much listed out the changes needed to make an A65 into a -14. I suspect the pistons it refers to increase the compression.

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

I think Mike is looking for information from the factory. The pistons are waffled for more surface area when the oil hits them, no compression increase.
EO

[N96337]

Re: BC12-D A65 to A75 Conversion

You could call Lycon and get ahold of Loren Lemen... 559-651-1070 or email [email protected] ....he was a tech rep for Continental for many years, and just went to Lycon....I'd bet he could fill you in right off the top of his head. Great guy!!
John

[Ragwing nut]

Re: BC12-D A65 to A75 Conversion

I think Mike is looking for information from the factory. The pistons are waffled for more surface area when the oil hits them, no compression increase.
EO

The 75 pistons are waffled. and the 80 pistons are waffled, higher dome and 5 ring. there is a 3 ring and 4 ring 65 piston, but the tcds does not specify the actual parts.

I just read the data sheet and sounds like all the changes to make one a 75. I guess I will have to dig out one of my very old parts books and look.

[CStence]

Re: BC12-D A65 to A75 Conversion

Barnstormer...
You are right. My FSDO kicked the 337 back rather rudely, stating that they weren't allowed to approve such a thing and I'll have to get an STC. THAT is going to be a headache. If I'm lucky the ACO won't give me much trouble for a one-time STC but more than likely they're going to want DER's and such. Sheesh. All for a measly 10HP. How is it the FAA got so smart in 2004 that now they know more than all of their predecessors?

The thing is, the owner is up the proverbial creek because he had his prop repitched and cut to 72"...it is now 1/2" too short for what the Type Cert allows. Even if I talk him into going back to the A65 he'll have to buy a new prop.


Ragwing...
The only information I've found on the A65-14 is what I qouted from the Type Certificate. The odd thing is that it appears the A65-14 makes 75HP at 2675 RPM whereas the A75 makes 75HP at 2600 RPM. That makes little sense to me, but that is what the Type Certs say.

[CStence]

Re: BC12-D A65 to A75 Conversion

Update:

I've heard back from the ASI at the FSDO. I asked him if I could get an approval to simply de-rate the A65-14 to 65HP at 2350RPM (via the prop). In this way the aircraft could be airworthy until such point that I get a one-time STC for the extra hp.

He claims that FAA Order 8900.1 precludes him from doing that because it was previously installed. I told him that I have grounded the airplane and am awaiting the approval before it goes any further...even going so far as to say that I could literally remove the engine and reinstall it so it would be a fresh install. The ASI replied that while there is no rule against that in the FARs I would be "convaluting" the rules. He went on to say I shouldn't "stick my neck out" for a pilot, almost as if I would be stirring up trouble for myself if I pursued this further.

I've got a call into the manager to question him on this but I'll be honest - the thought of making enemies at my FSDO is not a pleasant one.

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

I'm not really following you on the problem. What ever this -14 engine is it still has a max continuous rating of 65 horsepower. The only increase is in take off power. It's still an A65 and shouldn't need any paperwork to justify the installation. Unless there is more to this story.
EO

[Popsdory]

Re: BC12-D A65 to A75 Conversion

Is there any way that I can just look at my engine to see if it is a 65 or 75? I mean other than the data plate? It sounds like all of the parts to change it are internal is that correct? My logs data plate etc. say 65 but there is a letter from one owner to another included in the logs that says it was upgraded to 75 at overhaul.. As far as anyone is concerned, it's a 65, if I toss the letter right? Or can it be seen? Still has the stock 65 prop.

[Edwin Otha]

Re: BC12-D A65 to A75 Conversion

Lots of people will install the A75 components as a reliability upgrade. The only way to get the power is to spin it at 2600 RPM. If your prop limits the engine at 2300 it only makes 65 HP.
If the plate says it's a 65, it's a 65, regardless of your letter.
EO

[Ragwing nut]

Re: BC12-D A65 to A75 Conversion

Update:

I've heard back from the ASI at the FSDO. I asked him if I could get an approval to simply de-rate the A65-14 to 65HP at 2350RPM (via the prop). In this way the aircraft could be airworthy until such point that I get a one-time STC for the extra hp.

He claims that FAA Order 8900.1 precludes him from doing that because it was previously installed. I told him that I have grounded the airplane and am awaiting the approval before it goes any further...even going so far as to say that I could literally remove the engine and reinstall it so it would be a fresh install. The ASI replied that while there is no rule against that in the FARs I would be "convaluting" the rules. He went on to say I shouldn't "stick my neck out" for a pilot, almost as if I would be stirring up trouble for myself if I pursued this further.

I've got a call into the manager to question him on this but I'll be honest - the thought of making enemies at my FSDO is not a pleasant one.

I am sure he probably does not know the difference between a j-3 or a dc-3. Try and contact eric minnis, member here, he use to be FSDO in that area, but not sure if he is still FSDO. If need be, I would pull cylinders and convert back to -8 via continental sb and be done with it.