Is spinner part of airframe?

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skipnsb

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skipnsb
Am I correct that the spinner and spinner bulkheads are considered a part of the airframe, rather than a part of the engine or propeller?
 
Well if you were planning to get your engine or propeller overhauled would you send them the spinner?
 
My context is whether a change of spinner is a major alteration, and does the vintage aircraft parts substitution advisory circular help support a change of spinner as being a minor alteration.

Specifically, I want to use a TCBS composite spinner (approved by stc on a later model of my aircraft (same type certificate) ) on my earlier model as a minor alteration.

My reading so far indicates that it is easier to justify it as a minor alteration to the airframe than if it was considered an alteration to the propeller or engine.

I understand its the ap's decision on whether to log it as a minor alteration, and later if the ia will find fault with it at the annual inspection.

I will brief my analysis and post for criticism. Am I missing something obvious? Thank you.
 
skipnsb said:
My context is whether a change of spinner is a major alteration,
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I would think so, since changing the spinner can materially affect engine cooling and the aerodynamics around the prop.

and does the vintage aircraft parts substitution advisory circular help support a change of spinner as being a minor alteration.
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I think that's a question for your local FSDO Airworthiness Inspector.

Specifically, I want to use a TCBS composite spinner (approved by stc on a later model of my aircraft (same type certificate) ) on my earlier model as a minor alteration.
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The fact that the spinner is STC'd on another model of the same plane might be adequate approved data for field approval of its use on your model, but again, that's a question for your FSDO Airworthiness folks.

My reading so far indicates that it is easier to justify it as a minor alteration to the airframe than if it was considered an alteration to the propeller or engine.
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I can't say whether that's true or not.

I understand its the ap's decision on whether to log it as a minor alteration, and later if the ia will find fault with it at the annual inspection.
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...or if the FAA somehow gets involved (lots of ways for that to happen) and they decide it wasn't minor. My opinion is this is a case where it's better to ask permission than forgiveness.
 
If it is installed by STC on the newer plane I think you might have your answer, is the STC a modification of the prop engine or airframe?


If an STC is required to install, that may have some bearing on the whole major/minor alteration too.
 
skipnsb said:
My context is whether a change of spinner is a major alteration, and does the vintage aircraft parts substitution advisory circular help support a change of spinner as being a minor alteration.

Specifically, I want to use a TCBS composite spinner (approved by stc on a later model of my aircraft (same type certificate) ) on my earlier model as a minor alteration.

My reading so far indicates that it is easier to justify it as a minor alteration to the airframe than if it was considered an alteration to the propeller or engine.

I understand its the ap's decision on whether to log it as a minor alteration, and later if the ia will find fault with it at the annual inspection.

I will brief my analysis and post for criticism. Am I missing something obvious? Thank you.
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What you should be asking for on a 337 is a deviation to the STC for the later model aircraft.
 
Propeller parts, some prop spinner and backing plates are aircraft part numbers, such as the 172 fixed pitch spinner. the part number comes from the Aircraft IPC.

Many constant speed propellers the spinner and backing plates are propeller manufacturers part numbers.

So be careful where you get your advice on what to do in replacing one part with another, when the spinner is an aircraft part number simple parts replacement rules apply. If the spinner is a portion of the prop system, it may require the whole test and evaluation routine to gain authorization to substitute one for another.

Ron almost got it right when he implied the Data from 1 STC can be used for authorization to use it on another aircraft model that is not on the application list of the STC. That is called a deviation to the STC and is often granted by the 337 approval methods. This may or may not be a simple thing to do, the FAA may want the whole flight test to grant the deviation, or not.
 
skipnsb said:
My context is whether a change of spinner is a major alteration, and does the vintage aircraft parts substitution advisory circular help support a change of spinner as being a minor alteration.
That is not a minor alteration, it is a change of type design. thus a major alteration

Specifically, I want to use a TCBS composite spinner (approved by stc on a later model of my aircraft (same type certificate) ) on my earlier model as a minor alteration. Then you must do 1 of 2 things, either get the holder of the STC to add your aircraft to the application list or gain a deviation to the STC thru the 337 approval methods.

My reading so far indicates that it is easier to justify it as a minor alteration to the airframe than if it was considered an alteration to the propeller or engine.

I understand its the ap's decision on whether to log it as a minor alteration, and later if the ia will find fault with it at the annual inspection.

I will brief my analysis and post for criticism. Am I missing something obvious? Thank you.
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I think any A&P-IA doing an annual will spot it and require some method of approval to substitute the parts.
 
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