Doyne conversion

[c170b53]

Should be in your general inbox Bruce. To all I received this bit of paperwork from a club member some time ago and I had forgotten about it and also we may already have it on file. Sadly I forget who sent it to me but I do remember sitting on the stuff for awhile and thus I owe that gentleman a few. Hope its of use to others.

[Gary Gades]

Still looking. . I have the stc cover sheet and the drawings but need the operating limitations. Any help would be appreciated.

[c170b53]

This may help and I think its in the associations tech library.

Mod: It's in our library now: http://www.cessna170.org/forums/viewtop ... =31&t=9024

[n2582d]

Jim,
Unfortunately, that is not the AFM supplement that Gary needs as he has a 170B. According to the STC SA3-13 cover sheet in the Maintenance Library there are two other AFM supplements: one for the 170B seaplane and the one he needs which is dated 1/23/57 for the 170A or 170B landplane or skiplane.

[c170b53]

Gary (2) my mistake

[Bruce Fenstermacher]

Gary G, if you can't turn up the exact version of the AFM supplement I'd take all the copies of the other AFMs we have (including the Bush STCs which were Doyn or copies of Doyn STCs) to the FAA and show them that they didn't really change much and have lots in common. Changes were in the specific engine model or HP for that engine model and perhaps the prop.

The actual performance claimed for each of these STCs never changed from the stock claiming only to at least meet them.

Perhaps the FAA would accept Jim's AFM for the A model for your B model as the only thing that would change is the wording in the header.

[Gary Gades]

Bruce , I'm sure you are right about the supplements being very similar as the Doyn supplement for their O 360 conversion is very similar to the factory supplement. I did find a member (beaverbill) that has offered to make me a copy of his hopefully sometime next week. The concern with the supplement is that if there is an rpm range to avoid as that propeller is only used on that engine. I know that the engine prop combo has been running in that config since the 50's but I would like to know. I don't want to fudge on the supplement and send it in only to have someone at the fuzz office (with nothing better to do) pull the real one out and find a difference. I even went so far as to provide them with n#'s of planes with 340's in them to look up the stc/337's and no dice, had to provide that on my own. I'm getting there with the paperwork, slowly but surely and appreciate all the help.

[Gary Gades]

Too bad i can't make that one work as it references the drawing number of 1099 that matches the drawing number on the kit tag in my logbook

[Bruce Fenstermacher]

I don't want to fudge on the supplement and send it in only to have someone at the fuzz office (with nothing better to do) pull the real one out and find a difference.

To be honest I don't think the FAA actually has any of these STCs. They called us a year ago to get copies of our STC for their review for another member. You think our STC is the only one "misplaced".

I'd would not represent the AFM we have as the actual AFM but likely the same. And I'd show them the others to prove the point. If they can show you better info, you of course would rather use it.

[blueldr]

A few years ago a friend of mine had an airplane, a '52 C-170B, come in for an annual. He was not an IA, but had a friend that was who used to do the sign off. The airplane owner had just bought the airplane from the estate of the previous owner who had recently passed away. He flew it in waaaaayyyy out of license without a ferry permit due to ignorance of the requirement.
My buddy got to looking the airplane over and found that it had a Lycoming O-340. The log book didn't seem to mention that any place. Then he noticed that the left wing had an "L" shaped tank cover. The log book could not account for that either. Further investigation revealed that it was a C-175 wing with a C-170 fuel tank in it. Not in the log book either, naturally. It also had a "U" yoke and Rams Horn control wheels, Cleveland wheels and brakes, C-180 gear legs and 8.50 tires. There were other things too.
My buddy and his IA got together with the owner and convinced him to quietly fly the airplane away some evening and please never bring it back. Life is just too short for some jobs.

[Gary Gades]

Well, I don't have that 170, my mess is not that bad. I have had a very similar conversation with the previous owner however.

[Gary Gades]

Log entry for O340

[shanmoon]

Sorry to resurrect such an old thread, but I've got this STC on my Cessna and I have run into a problem.

Long story short, the prop governor was pulled off after an unrelated engine repair to mags. Afterwards the prop was no longer cyling properly. The governor was sent to a prop shop and I was told it was fine. However, per the mechanic the prop arm conenctor on the governor was not standard, and the shop sent it back with what they thought was the correct one (but unable to be sure without STC paperwork).

That arm would not connect up properly due to the angle that the prop governor is mounted at, so the local mechanic put back on the original arm. He said the arm was bizarre and like nothing he had ever seen....with a bending joint in the middle, and it kind of looked home made.

The problem is now that the governor has been put back on, I am now longer getting max rpm. At full power I usually got 26=27" mp and 2600-2700 rpm. How I am only getting 2350Rpm at full run up. I was hoping maybe someone here with the STC has some documentation or info about the governor or arm? Photos of the arm of the arm would help immensely. I did a test flight around the airport (long runway so I had lots of room for error) and found my climb was about 150fpm slower as well (which I would expect with the lower RPM).

I had a pre-buy inspection and annual done on the plane before purchase, and unfortunately the unusual prop arm was not caught. At this point my plane is grounded. I sure am hoping to get this figured out soon as I have CFII checkride scheduled in about 5 weeks that I was hoping to do in this plane (I bought it for time building).

Again, any help at all would be hugely appreciated. For some reason even though I am logged in and a paid member of the association I get a not authorized error when I try to hit any of the attachment links in the thread or archive.

[GAHorn]

shannon, according to the Doyn STC your constant speed prop should see 2700 RPM at takeoff power. If your prop governor is set incorrectly then you will not acheive that RPM. There should be an adjustment on it to allow the full 2700 when the throttle is fully advanced (regardless of elevation if MP meets takeoff criteria….likely 25” or more.)

[shanmoon]

Yep I typically saw around 27MP 2700 RPM. The control in the cockpit is fully advanced. So sounds like it could be that the timing was change slightly at the shop vs the oddball prop arm beingstalled improperly? Are you aware of any STC paperowk that states this is how the timing is set?

Thanks for the response!