C-145 Crankshaft Question

[GAHorn]

Ahhh....how the plot thickens....

The FSDO which called Bruce is doubtless the same which called me, totally unaware that yet a third FSDO was actually in authority within the FAA Region which has jurisdiction over the actual airplane/operator (fellow Member Don Khulensmidt) who had been in contact with myself, along with his mechanic/A&P/IA and the FSDO Inspector who fully understands the issue and told me in-person that he intended to issue a "Field Approval" for Dons skull-cap on his EM-Prop/converted engine.

Sometimes the left-hand (lady Inspector) and the right-hand (FSDO of jurisdiction) aren't talking or are unaware of each other.

So many cooks.... only one kettle-of-fish....

[Bruce Fenstermacher]

The point is that just because it makes sense to most of us here at the forum familier with such things doesn't mean the Fed is going to see it that way.

The problem is in todays world you must specifically spell everything out. You can not leave room for common sense. In the case of the early 8 bolt crank installed in a -D engine, it would make sense that you could use the props and spinners from the TCDS. Our STC says what props are approved and they are not found in our TCDS. In our case no one considered that a -D might have an 8 bolt crank and so those props are not listed and so they can not be used depending how you read our STC. Same with the spinner. Since you would need a 6 bolt spinner for a -D engine those that are appropriate are listed. The skull cap can be bolted to either the 8 or 6 bolt crank and is approved why would one question if it could be used except it is not listed on our STC. Now that it appears a inspector feels he needs to issue a field approval for the skull cap spinner which muddies the water. In effect he has decided the skull cap is not approved or more likely we isn't deciding that but issuing an approval in case someone else thinks it's not approved. CYA

So what we have to do is get our STC amended to include the skull cap spinner and allow the use of props and spinners included in the TCDS should the -C-D or E have an early 8 bolt crank installed. When I inquired of the women inspector how to go about getting this done she said she could help. So again I have to follow up as I'd forgotten all about it till this thread.

[ron74887]

N4200v, Don't do anything--I have a copy of an STC that makes it leagal to install the 8 bolt crank inthe 0-330-D case I will send a copy to Bruce/George. The owner gave us permission to use at will and I have that letter also. I'd attach it here to not computer savvy enough. Ron Massicot

[ron74887]

another thing this is the same configuration President Jim W has in his plane. The long argument is whether it needs our STC. Our STC basically covers the previously unapproved Props. Since this has the original approved prop is our STC necessary??? Jim bought it (STC)just to cover the bases and got of copy of this STC also. Ron

[GAHorn]

Oh, what a complicated web we weave.....

Well, a big THANK YOU to the STC Owner and to Member Ron Massicot for this.

I don't know how popular this mod will be since:

1- It uses a hard-to-find/expensive crankshaft.
2- It requires O-300-D owners to change to another propeller OR it saves a DM/MDM prop owner from having to change props but requires another STC (ours) to install the engine in a certificated airplane such as a C-170.
3- If a different prop is installed on a D engine, the combination is not approved for any certificated airplane unless additional approval (such as our STC) is provided.
4-The spinner becomes another concern to some Inspectors.

IN other words, to install a "D" engine in a 170 will still require approval such as our STC, IMO, with the added complications of prop and spinner.

BUT, if an owner of a good DM or MDM prop simply wanted to save his old obsolete prop and use it on a D engine which he wishes to get approved on a certificated airplane (in other words, spend $5-Grand for an A-crank to save $2500 on a new prop) .... ...and then deal with all the other legality issues... this could be useful paperwork if the letter is genuine. (It's not notarized, dated, the owner is unidentified, no contact info provided, or otherwise verified. A person who goes to all this trouble may find themselves with more expenses than anticipated.)

But, otherwise, Mrs. Lincoln... How was the play?

[ron74887]

well the argument starts by changing the Prop only does that convert the D to an A per continentals papers?? Does the vacuum pump and starter make an A a D because there is an STC that you can put the D accessory case on an A and have the angle drive starter and vacuum pum?? INCOMING RON

[Bruce Fenstermacher]

There is no argument. If you change the crank to an 8 bolt crank in order to convert a -D to a -A then you would also have to remove the angle starter and vacuum pump. Now if you had a bases of approval for the angle starter and vacuum pump to be installed on a -A model then you could leave them on.

[GAHorn]

There is no argument. If you change the crank to an 8 bolt crank in order to convert a -D to a -A then you would also have to remove the angle starter and vacuum pump. Now if you had a bases of approval for the angle starter and vacuum pump to be installed on a -A model then you could leave them on.

It's a simple matter: The conversion is not complete until the paperwork is done. Either perform the TCM M75-6R1 Service letter for engine conversion... or use the Johnson STC to install the crank and prop into an O-300-D...which is illegal installed into a 170 without a basis of approval (such as our STC.)

[wingnut]

Well here is a good place for me to ask about the O-360 Crank. I think it was two years ago, I believe Del mentioned that the 360 crank would work in the O-300.....Any new knowledge on that idea?

I just wanna know how I got involved I seem to remember bits and pieces...................... But I'm not an engine guy

[Bruce Fenstermacher]

But I'm not an engine guy

Del, any chance you stayed at a Holiday Inn like I did last night. That's all it took for me to become an expert.

[GAHorn]

Brad probably meant Harry Dellicker...."Dell"

[wingnut]

But I'm not an engine guy

Del, any chance you stayed at a Holiday Inn like I did last night. That's all it took for me to become an expert.

Bruce, now I know I can never live up to your standard. Ya see, I'm a Motel 6 guy

[N4200V]

Getting back to my crankshaft question. on whether I can legally use the 8 bolt crank in the O300D. I am going to try and do some research on the engine itself and see if back in 1971 or before if there was a field approval at the time of installing this crank. Wasn't there more than one application for this engine? If so wouldn't this clear everything up? Greg

[GAHorn]

Greg, I hope you'll find that there was a basis of approval for installing an "8-bolt" crank in your O-300-D...(and also docs for that engine and prop combination to be installed in your airplane).... but I hope if you do that the documentation is a bit more than that simple statement. I wonder if you know if your crank is dampered? or if you know it's specific part number?
O-300-D engines were installed in several aircraft, some by OEM and specified in Type Certificate Data Sheets (TCDS). Some by STC. Some by Field Approval. But I believe it's safe to say that all O-300-D engines had dampered crankshafts with 6-bolt prop flanges. The thought I'm experessing is that hopefully a dampered crankshaft is installed...not an early C-145 crank,....otherwise an operating limitation should probably be placed upon the engine against 35A or larger generators.

If you cannot find any documentation on your crank installation, then you might consider having your engine inspected and it's logs revised to show that Mr. Johnsons STC was found to be installed, if your engine meets that crank PN, etc.. (i.e. dampered crank)

This discussion included many comments by myself and others of an anecdotal nature. My own comments mentioning the need to have the TIC170A STC as a basis of approval is actually not a simple matter, in your case. Why?
Because that STC specifies a certain series of propeller...which your modified engine does not utilize. In other words, your model "D" engine is not otherwise approved for a C-170, and our STC for installation of a "D" engine specifies a prop which has a 6-bolt hub....which your engine cannot use on it's 8-bolt crank.

This likely means a Field Approval or other basis will have to be found for your situation.

[blueldr]

Del,

When ya get to the Motel 6, please turn out the light, will ya.