337 form

murphey

murphey

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murphey
I've been reading thru Part 43 and am baffled. When is a 337 required to be submitted? Installed an STC'd strobe (Whelen) and there's an argument among some of the folks around the airport. With the STC, isn't it merely a logbook entry by the A&P?

Another ongoing battle - someone (not me) is claiming that a 2 pound weight difference requires the 337. This is completely illogical.
 
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murphey said:
I've been reading thru Part 43 and am baffled. When is a 337 required to be submitted? Installed an STC'd strobe (Whelen) and there's an argument among some of the folks around the airport. With the STC, isn't it merely a logbook entry by the A&P?

Another ongoing battle - someone (not me) is claiming that a 2 pound weight difference requires the 337. This is completely illogical.
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All STC's are a modification. and are entered in the aircraft history records by a 337 approved by the inspection A&P-IA.

Read the top of the back page..
 
Tom-D said:
The clue is in the title of the form.


http://www.faa.gov/documentLibrary/media/form/faa337.pdf
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yes, I know. I've read it. That's why I'm asking the question here.

Here is how to fill it out

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%2043.9-1F/$FILE/AC%2043.9-1F.PDF.
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Tom, please I didn't ask how to fill it out. And I'm very aware of the word "major" in the title. However nowhere is the phrase "major alteration/major whatever" ever defined. Even among the A&Ps at the airport it seems to be almost urban legend when to fill out a 337.
 
FAR 1.1

Maintenance means inspection, overhaul, repair, preservation, and the replacement of parts, but excludes preventive maintenance.

Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications—

(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.

Major repair means a repair:

(1) That, if improperly done, might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.

end quote

so you see weight changes play a big part in major repairs and alterations.
 
Any alteration such as a STC requires a 337.

any patch/repair/change of any kind will require a 337 as a pre-approved data, as the STC is or a field approval approving the data that you submit to FSDO.
 
murphey said:
yes, I know. I've read it. That's why I'm asking the question here.

Did you notice the word Alteration? Your STC is an alteration, because the factory did not make it during assembly.


Tom, please I didn't ask how to fill it out. And I'm very aware of the word "major" in the title. However nowhere is the phrase "major alteration/major whatever" ever defined. Even among the A&Ps at the airport it seems to be almost urban legend when to fill out a 337.
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see FAR 1.1

and

http://www.ecfr.gov/cgi-bin/text-id...:1.0.1.3.21&idno=14#14:1.0.1.3.21.0.363.14.52
 
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Tom-D writes

Did you notice the word Alteration? Your STC is an alteration, because the factory did not make it during assembly.

Thank you. That's the criteria I was looking for.
 
murphey said:
Tom-D writes

Did you notice the word Alteration? Your STC is an alteration, because the factory did not make it during assembly.

Thank you. That's the criteria I was looking for.
Click to expand...

YAVW,
 
murphey said:
Tom-D writes

Did you notice the word Alteration? Your STC is an alteration, because the factory did not make it during assembly.

Thank you. That's the criteria I was looking for.
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Not quite so. Minor alterations do not require a 337. The issue is the second criterion Tom mentioned -- not done according to accepted practices or elementary operations. If it was done according to accepted practices or elementary operations, it wouldn't need an STC. Since whatever was done to your airplane does need an STC, it must be beyond that scope, and thus constitutes a major alteration and needs a 337.
 
Per AC 120-77 you get this.....

repair-decision-chart.jpg
 
Ron Levy said:
Not quite so. Minor alterations do not require a 337. The issue is the second criterion Tom mentioned -- not done according to accepted practices or elementary operations. If it was done according to accepted practices or elementary operations, it wouldn't need an STC. Since whatever was done to your airplane does need an STC, it must be beyond that scope, and thus constitutes a major alteration and needs a 337.
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That's true, but we were talking about an STC, that by nature is a major modification which has been approved for multiple applications. and is required to have a 337 to enter it into the aircraft history records.
 
A note :

The new STCs will have a statement in the installation instructions that will say " fill out a 337, and redo the weight and balance" or words to that effect.
 
flyingmoose said:
Per AC 120-77 you get this.....

repair-decision-chart.jpg
Click to expand...

AC 43-120 is to guide the mechanic in gaining approval of an alteration on a 337 (Field approval)

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/list/AC%2043-210/$FILE/AC43-210.pdf
 
But worth knowing that some mods that might be thought at first blush to require an STC are instead classified as minor and don't require such. The Alpha AOA system just installed in my plane is a good example.

Tom-D said:
That's true, but we were talking about an STC, that by nature is a major modification which has been approved for multiple applications. and is required to have a 337 to enter it into the aircraft history records.
Click to expand...
 
An STC doesn't automatically mean that a major alteration is being performed. A good example would be clamping a set of Rosin sun visors onto tubing - nothing even remotely "major" about it but all Rosin visors are covered under their STC so after clamping them to the tubing you fill out a 337 form and that is solely because you are incorporating something that has a Supplemental Type Certificate onto your aircraft.

Rosin doesn't really have to have an STC associated with their visors but having one greatly simplifies, or maybe a better way to put it is "standardizes" the paperwork so that there are no questions or ambiguities as to the approval of the installation. Having the STC and associated 337 should give you a warm fuzzy feeling that will offset the bigger hole in your wallet.
 
on a mooney website, one of the members installed the LED lights and the IA signed it off as a minor alteration; no 337. Another guy had the LED lights installed with a HID landing light. He did pursue a 337.
 
Silvaire said:
An STC doesn't automatically mean that a major alteration is being performed. A good example would be clamping a set of Rosin sun visors onto tubing - nothing even remotely "major" about it but all Rosin visors are covered under their STC so after clamping them to the tubing you fill out a 337 form and that is solely because you are incorporating something that has a Supplemental Type Certificate onto your aircraft.

Rosin doesn't really have to have an STC associated with their visors but having one greatly simplifies, or maybe a better way to put it is "standardizes" the paperwork so that there are no questions or ambiguities as to the approval of the installation. Having the STC and associated 337 should give you a warm fuzzy feeling that will offset the bigger hole in your wallet.
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:yeahthat:

In many cases the STC and 337 installing it, is only to inform the FAA that this is how the aircraft is configured.
 
IF I am not mistaken, the Whelen LEDs are STC and PMA'd as well. Mine were installed under the STC with a log book entry only by my A&P / IA
 
rbridges said:
on a mooney website, one of the members installed the LED lights and the IA signed it off as a minor alteration; no 337. Another guy had the LED lights installed with a HID landing light. He did pursue a 337.
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The two are different, per my understanding. Whelen has a PMA, which means that even though the item is different construction, it is a legal bolt-in replacement.

LoPresti (and I assume others) had HID landing lights available that are similar to the kind you get for your car. Those required an STC, and thus a 337. That makes sense, because HIDs typically require a ballast that is installed somewhere other than the light. PMA parts typically need to bolt right up in the existing location. The Whelen landing lights bolt right in place of the good ol' GE incandescent units.
 
Ted DuPuis said:
The two are different, per my understanding. Whelen has a PMA, which means that even though the item is different construction, it is a legal bolt-in replacement.

LoPresti (and I assume others) had HID landing lights available that are similar to the kind you get for your car. Those required an STC, and thus a 337. That makes sense, because HIDs typically require a ballast that is installed somewhere other than the light. PMA parts typically need to bolt right up in the existing location. The Whelen landing lights bolt right in place of the good ol' GE incandescent units.
Click to expand...

I figured the HID was the reason for the 337. I was just trying to find a couple of examples, and those were the first that came to mind.
 
rbridges said:
I figured the HID was the reason for the 337. I was just trying to find a couple of examples, and those were the first that came to mind.
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For accessories, PMA is the way to go if you can swing it. SkyTec has done a great job PMAing starters (and now PlanePower PMAing alternators). Whelen is working on PMAing the various LED lights they have for the rest of the plane, which is a wonderful thing. We're likely going to give them more business in part because of this, and put LEDs on other parts of the plane.
 
DutchessFlier said:
IF I am not mistaken, the Whelen LEDs are STC and PMA'd as well. Mine were installed under the STC with a log book entry only by my A&P / IA
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IF the aircraft was equipped with the strobes the PMA is for a direct replacement part.

If the Aircraft was not equipped prior, the STC is to instal a new item to the aircraft.
 
The Whelen's come with both a PMA and their old STC form in the box before they had finished PMA. You get to choose. LOL.
 
Tom-D said:
IF the aircraft was equipped with the strobes the PMA is for a direct replacement part.

If the Aircraft was not equipped prior, the STC is to instal a new item to the aircraft.
Click to expand...

That depends. Whelen has managed at least with the LED landing/taxi lights to get a PMA. They've also managed it with a few other lights where the PMA replaces what was previously an incandescent item.

Look for this more in the future. Hopefully they'll eventually be able to extend it to magneto replacements.
 
Ted DuPuis said:
That depends. Whelen has managed at least with the LED landing/taxi lights to get a PMA. They've also managed it with a few other lights where the PMA replaces what was previously an incandescent item.

Look for this more in the future. Hopefully they'll eventually be able to extend it to magneto replacements.
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That enters into the fit form and function rules that are never applied the same from FSDO to FSDO.

Here is the question, If the Whelen STC was applied to your aircraft, does it require a PMAed part to replace the bulbs/LEDs?

or are you replacing the bulbs/LEDs with regular replacement parts?
 
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An STC doesn't automatically mean that a major alteration is being performed. A good example would be clamping a set of Rosin sun visors onto tubing - nothing even remotely "major" about it but all Rosin visors are covered under their STC so after clamping them to the tubing you fill out a 337 form and that is solely because you are incorporating something that has a Supplemental Type Certificate onto your aircraft.
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Isn't another way of saying this that Rosen got the STC as a marketing stunt, to silence all the A&Ps out there who cannot be bothered to read Part 43 Appendix A and determine that changing a sun visor is not a Major Alteration ;)
 
peter-h said:
Isn't another way of saying this that Rosen got the STC as a marketing stunt, to silence all the A&Ps out there who cannot be bothered to read Part 43 Appendix A and determine that changing a sun visor is not a Major Alteration ;)
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Not arguing with this statement, because there is some truth to that.
There are some Rosen installs, however, that require drilling new holes in the structure. I would imagine that requires the STC.
 
Surely, drilling holes in an unpressurised hull can be done under AC43-13?

That is how radio/TCAS antennae are done, so a visor should be no different.

Here in the UK, there are certain shops that insist on a DER package for any drilling - even fitting a mounting bracket for say a TAS box to the luggage compartment floor. Obviously this is a ripoff (at $2000) but few customers will know that.

I just don't believe that an STC is needed for this work. The FAA regs list stuff which needs an STC and there is no way IMHO a visor mount could be in that category unless the holes fall in a structurally vital piece of metal.
 
peter-h said:
Surely, drilling holes in an unpressurised hull can be done under AC43-13?

That is how radio/TCAS antennae are done, so a visor should be no different.

Here in the UK, there are certain shops that insist on a DER package for any drilling - even fitting a mounting bracket for say a TAS box to the luggage compartment floor. Obviously this is a ripoff (at $2000) but few customers will know that.

I just don't believe that an STC is needed for this work. The FAA regs list stuff which needs an STC and there is no way IMHO a visor mount could be in that category unless the holes fall in a structurally vital piece of metal.
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Do you call the front spar carry thru a vital piece of metal?

because that is the place that the sun visors attach to the Cessna 100 series.
 
peter-h said:
Surely, drilling holes in an unpressurised hull can be done under AC43-13?

That is how radio/TCAS antennae are done, so a visor should be no different.

Here in the UK, there are certain shops that insist on a DER package for any drilling - even fitting a mounting bracket for say a TAS box to the luggage compartment floor. Obviously this is a ripoff (at $2000) but few customers will know that.

I just don't believe that an STC is needed for this work. The FAA regs list stuff which needs an STC and there is no way IMHO a visor mount could be in that category unless the holes fall in a structurally vital piece of metal.
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Even if you were drilling into a piece of plastic you are installing equipment that was not part of the original type certificate. The STC is going to help you get the 337 finished. I agree that it shouldn't be that complicated to get some things done but its the world we live in.
 
flyingmoose said:
Even if you were drilling into a piece of plastic you are installing equipment that was not part of the original type certificate.
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There are a great many things that can be done in non structural parts that are considered a minor modification.
 
Tom is right. Minor alterations do not require a 337 or an STC. A minor alteration is an alteration that is not major.

Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications—

(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.
 
FlyWithScott said:
Tom is right. Minor alterations do not require a 337 or an STC. A minor alteration is an alteration that is not major.

Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications—

(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.
Click to expand...

The quandary is, if you must drill a hole, did you alter the structural strength ?
 
The "appreciably" part is interesting as well.
 
Tom-D said:
All STC's are a modification. and are entered in the aircraft history records by a 337 approved by the inspection A&P-IA.

Read the top of the back page..
Click to expand...

Tom-D said:
Any alteration such as a STC requires a 337.

any patch/repair/change of any kind will require a 337 as a pre-approved data, as the STC is or a field approval approving the data that you submit to FSDO.
Click to expand...

They above is what Tom said earlier. It is the same as I am saying. STC requires a 337 because you are modifying the type certificate. Even if it is minor the FAA whats to know what all has been modified on the aircraft.

FlyWithScott said:
Tom is right. Minor alterations do not require a 337 or an STC. A minor alteration is an alteration that is not major.

Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications—

(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.
Click to expand...
I know where the definitions are thanks. FSDO here says any STC product automatically requires 337. Now if its different elsewhere IDK.
The above produce that was discussed was the Rosen shade. I agree that It comes with STC.
 
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flyingmoose said:
They above is what Tom said earlier. It is the same as I am saying. STC requires a 337 because you are modifying the type certificate. Even if it is minor the FAA whats to know what all has been modified on the aircraft.


I know where the definitions are thanks. FSDO here says any STC product automatically requires 337. Now if its different elsewhere IDK.
The above produce that was discussed was the Rosen shade. I agree that It comes with STC.
Click to expand...


Exactley do you think a company would spend all the money on getting an STC approved if their product could be installed as a minor mod without an STC?
 
flyingmoose said:
... Even if it is minor the FAA whats to know what all has been modified on the aircraft.
Click to expand...

Why do you think the FAA wants to know if the aircraft has a minor alteration? Why do they need to know this? They don't care.

VanDy said:
Exactley do you think a company would spend all the money on getting an STC approved if their product could be installed as a minor mod without an STC?
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Why do you think an STC for Rosen sunvisors cost the company very much at all? It's not the same as getting an STC for a different engine approved. Something minor may take take some paperwork and time but there are lots of STCs for minor things that have been approved for little cost. I suspect as a marketing ploy, the STC owners planned on making a few bucks selling the STC for their "FAA Approved" alteration which probably didn't require one in the first place.
 
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