Skull Cap and O-300 D?

[Fearless Tower]

Looks like I am going to change the engine on my '48 to an O-300 D. The replacement engine I have lined up comes with the prop, so I am covered there. Obviously I will be doing the STC to upgrade the engine. I know that the prop bolts are a different arrangement, but wondering if I can still use my skull cap spinner on it. I think the answer is yes since the skull cap has no back plate, but would like to know for sure since I am not currently co-located with either the engine or my airplane at the moment.

[bagarre]

Can or May?

Do a search on here for the skull cap spinner, there are tons of conversations about it.
In short, the STC lists two spinners by part number and the skull cap isn't one of them. It want intended to exclude the skull cap but many a person interpret it that way

[blueldr]

I can't imagine that anyone other than a really cranky IA would ever squawk a skull cap spinner.

[Bruce Fenstermacher]

I'd put the skull cap on till someone squawks. Then I'd run it with no spinner til we get it straight.

[Fearless Tower]

I'd put the skull cap on till someone squawks. Then I'd run it with no spinner til we get it straight.

After reading the Skull Cap vs STC thread, I thought the issue was that the STC requires a spinner to be installed?

[Bruce Fenstermacher]

No, the STC is silent on runing no spinner or the use of the skull cap. It does list 6 bolt spinners because, after all, the STC allows the installation of a 6 bolt crank and the 8 bolt approved spinners WILL NOT work. When the STC was developed it was not considered that anyone would question whether the skull cap or no spinner could be used because there was not physical reason they couldn't and it was allowed already the the TCDS.

In other words the STC is just what it's name implies. It is A SUPPLEMENT TO the TCDS. the STC does not restrict the use of anything already approved on the TCDS. It allows the use of additional items. And this BTW would be my argument if some asked.

But today, if something is not specifically listed, some people think it's not allowed. I deal with this all the time at work. Once the company list a procedure that would be approved by default all other procedures become unapproved.

[bagarre]

FWIW, 81D has had a skull cap on her O-300-D since 1973 without a squawk.

[GAHorn]

Bruce, that was one of the problems we ran into with one of our Members (Don Khulenschmidt) last year, if you recall.
Don wanted to install a skull cap in lieu of the bullet spinner.
His IA correctly questioned the fact that our STC installation instructions specify that a (bullet) spinner be included with the installation, and we assisted Don in obtaining a deviance via field approval. Ron contacted the controlling FAA regional office to revise the STC.

[Fearless Tower]

Bruce, that was one of the problems we ran into with one of our Members (Don Khulenschmidt) last year, if you recall.
Don wanted to install a skull cap in lieu of the bullet spinner.
His IA correctly questioned the fact that our STC installation instructions specify that a (bullet) spinner be included with the installation, and we assisted Don in obtaining a deviance via field approval. Ron contacted the controlling FAA regional office to revise the STC.

George,

Who do we need to call when it comes time to do this on my airplane? My IA friend in TX who is doing the work is a retired AF guy and while I haven't discussed this with him yet, I know he likes to do things by the book, so I suspect that the 337 is the way he will want to go.

Andrew

[GAHorn]

Bruce, that was one of the problems we ran into with one of our Members (Don Khulenschmidt) last year, if you recall.
Don wanted to install a skull cap in lieu of the bullet spinner.
His IA correctly questioned the fact that our STC installation instructions specify that a (bullet) spinner be included with the installation, and we assisted Don in obtaining a deviance via field approval. Ron contacted the controlling FAA regional office to revise the STC.

George,

Who do we need to call when it comes time to do this on my airplane? My IA friend in TX who is doing the work is a retired AF guy and while I haven't discussed this with him yet, I know he likes to do things by the book, so I suspect that the 337 is the way he will want to go.

Andrew

You have no choice, Andrew. An STC requires a Form 337. (There seems to be an industry-wide misunderstanding about 337's. The Form 337 is a report made to FAA that a major repair or alteration has been made to an airplane.
Since the STC is indeed a major alteration, (the fact that it already has a basis of approval is no exemption from making the report) it must be complete and submitted.
What you likely meant by your reference to the 337 is, what is commonly called a "Field Approval", in which the repair or alteration has no previous basis of approval or has been applied similarly to other aircraft, ...and "block 3" of the Form 337 is used by FAA to review the description and "approve" the major repair or alteration in the "field" rather than thru the engineering offices of FAA. (These Field Approvals are becoming less popular as field inspectors are less likely to be qualified on more complicated/sophisticated, modern aircraft designs.)

The spinner matter has likely been resolved in that FAA having jurisdiction was requested to revise the STC to allow the skull cap or no spinner at all. I haven't seen the revision status since this came up, but perhaps Bruce has ....???

[Bruce Fenstermacher]

Yes George I am very aware of Don's IA's question. I'm also aware he is the first IA to question it though he may be the first IA to install a skull cap using the STC.

Here is the facts as I stated before. The STC does not restrict the use of any already approved spinner or lack there of. And it was not Ron' intent to do so. Ron pointed out that his own aircraft used to get the STC had a skull cap installed. But there is a paragraph in the installation instructions that refers one to a drawing which lists those spinners with the 6 hole bolt pattern and when taken literally could mean those are the only approved spinner combinations. Well they are IF your installing a bullet type spinner.

I know when the FAA contacted me and asked me for a copy of the STC as they couldn't find it, they indicated that they could not believe the skull cap would not be approved for the installation and I concurred. I do not know what the final ruling by the FAA was or how Don's skull cap was finally installed, if it ever was. The FAA inspector told me that if by some stretch the skull cap was not approved that the local FSDO guy intended to allow it under a separate approval.

I asked Ron to work with me as I had also been in contact with the FAA with regard to Don's question, to get an amendment or clarification on this spinner point as well as a few other things. Of course we've been a bit busy and haven't gotten back to Ron so I'd be surprised to find he has contacted the FAA. We do really need to do this and it is on my list of things to get done but I will not promise a time frame. But the itch needs to be scratched again so perhaps it's time to call Ron and get started.

So Andrew, if your IA thinks the installation of the skull cap is in question. This is a big if. Then your IA, not us, needs to contact his local FSDO for clarification and perhaps approval to install the skull cap.

----

I have a email in to Ron so we can all get on up to speed where we stand if different than what I've stated, and then move forward if necessary.

[GAHorn]

This not any effort on my part to bring up controversy....I'm only trying to be clear about this.
The "facts" as "stated before"...are not the facts. They are what you (and I and others) believe to be sensible....but are not the whole story.

The particular Member, and his IA, and his FSDO-Inspector and I, personally have all had conversations about this. The FSDO inspector called me directly on this particular matter and we both agreed it was only sensible that a skull cap or no spinner at all should be fine. The problem is its NOT ...because the STC specifically ONLY instructed that the bullet spinner be installed. This means it MUST BE installed. No other configuration was specified or allowed in the STC accomplishment instructions. If that particular bullet spinner is not installed....then the conversion is not accomplished in accordance with our STC instructions. And that..is the fact...until the instructions are changed and approved.

Yes...that is unfortunate...Yes, that seems ridiculous (even to the FSDO Inspector).....but nonetheless it was so.

Therefore, untill some basis of approval was otherwise obtained, ...Don's IA was correct. And our STC was deficient in that regard. It makes no difference what you, me, Ron, Don, the FSDO or bluEldr thinks....until there's a signature by a person authorized to approve a skull cap on Don's airplane using our STC ...it was not legal.

<edit for correction>"Melissa"... the lady in Denver FSDO called me and I reassured her it was merely an oversight made back when "times were simpler"....and she agreed also. But either the STC must be revised...or a seperate approval must be obtained to put a skull cap on a 6-bolt crankshaft using our STC.

Hopefully, she has issued that by now and the STC has been revised. I have only the copy issued several years ago. Perhaps Ron has a later version of events, and can answer this. Hopefully a revised copy is already issued.

(Don't let the specificity of my comments be misunderstood. I"m not trying to argumentive or didactic...I'm only trying to be specific and exact by stating matters this way.)

[Fearless Tower]

So Andrew, if your IA thinks the installation of the skull cap is in question. This is a big if. Then your IA, not us, needs to contact his local FSDO for clarification and perhaps approval to install the skull cap.

----

FWIW, when the time comes I'll give him a link to this and the other thread and we'll see what his take is and he can call the FSDO for the Field Approval......my next question is that if the skull cap needs a Field Approval to be installed with the STC as written, do we need two separate 337s? One documenting the install of the engine and a separate one documenting the Field Approval install of the spinner? Or can it be documented on a single 337

[blueldr]

This seems to me to be a problem that requires the use of an extra fine toothed comb.

[n2582d]

I asked Ron to work with me as I had also been in contact with the FAA with regard to Don's question, to get an amendment or clarification on this spinner point as well as a few other things. Of course we've been a bit busy and haven't gotten back to Ron so I'd be surprised to find he has contacted the FAA. We do really need to do this and it is on my list of things to get done but I will not promise a time frame. But the itch needs to be scratched again so perhaps it's time to call Ron and get started.

I have a email in to Ron so we can all get on up to speed where we stand if different than what I've stated, and then move forward if necessary.

Our association's STC SA01837SE for the O-300B on the C-170 has the same issue. It requires that the engine be installed in accordance with CES-2 which specifies a bullet spinner. If we get the O-300C/D/E revised to include the skullcap approved I wouldn't think it would be much additional work to get the O-300B STC revised at the same time.

For my O-300B I ended up buying a bullet style spinner so I can eventually attach weights when dynamically balancing the prop/engine. So the revision to allow a skullcap spinner is a moot point for me but I'm sure would help others.