The STC process

Tom-D

Tom-D

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Tom-D
AC-21-40 Chapter 2 para 2.2 (b.)

b. Applicant should submit a Certification Plan to the FAA for approval, (see figure 2-4) containing:
NOTE: Implementation of the certification plan will be at the discretion of the ACO Manager/Project Engineer. An implemented plan should also be revised throughout the program.

Who should write this plan?
 
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In my experience, working for helicopter OEM, the Cert Plan is written by the applicant and details how you intend to show compliance with the applicable FARs. The first response from the FAA may be a letter advising how long it will be before they will be able to look at your plan. With sequestration, manpower shortages and the low priority for certification activities it can be a long process.
 
Cert plans are typically written by an engineer. They go over how the program will comply with the appropriate FARs for what is being done. This is the first part that the FAA needs to agree with, because it outlines what you're going to do.
 
Tom-D said:
AC-21-40 Chapter 2 para 2.2 (b.)

b. Applicant should submit a Certification Plan to the FAA for approval, (see figure 2-4) containing:
NOTE: Implementation of the certification plan will be at the discretion of the ACO Manager/Project Engineer. An implemented plan should also be revised throughout the program.

Who should write this plan?
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The applicant writes the plan (sometimes using a hired gun).
 
There are guys who specialize in these things. While the ANS had some well versed A&P's /Repair station guys and a DER build up parts and ICA and submit AMOCs to the FAA, when it came down to getting the PMA we ended up with a hired gun.
 
Ted DuPuis said:
Cert plans are typically written by an engineer. They go over how the program will comply with the appropriate FARs for what is being done. This is the first part that the FAA needs to agree with, because it outlines what you're going to do.
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Yet engineers don't necessarily know squat about the FARs. Here, the "cert group" reviews and decides what FARs we need to show compliance with to approve the STC project. Depending on what the alteration is, you may need a lot of support.

Removing the OEM installed instruments system including the engine indication system and installing a glass panel on a Falcon 900 will involve lengthy testing by FAA pilots, including test flights in the experimental category.
 
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bnt83 said:
Yet engineers don't necessarily know squat about the FARs. Here, the "cert group" reviews and decides what FARs we need to show compliance with to approve the STC project. Depending on what the alteration is, you may need a lot of support.

Removing the OEM installed instruments system including the engine indication system and installing a glass panel on a Falcon 900 will involve lengthy testing by FAA pilots, including test flights in the experimental category.
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Well, keep in mind that my experience has been with slightly different setups than yours.
 
Anyone here interested in writing one?
 
What's the nature of the STC?
 
bnt83 said:
Cant answer a simple question? Sounds like the perfect candidate to work on an STC with.
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Why didn't you answer the original question?

My aircraft isn't the issue.
 
Tom-D said:
How would that matter to answer the question?
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Because then those of us who might be interested in writing will have a better idea of what you're asking.
 
Ted DuPuis said:
Because then those of us who might be interested in writing will have a better idea of what you're asking.
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To re-phrase the question, does it require a DER/DAR to write this plan?
 
Tom-D said:
To re-phrase the question, does it require a DER/DAR to write this plan?
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No. Your petition to the FAA would be for the DER/DAR to be delegated authority to approve said plan. You could write it if you felt up to it.
 
To take this a step higher, FAR 43-A says,

(xiii) Changes to the wing or to fixed or movable control surfaces which affect flutter and vibration characteristics.

How would you prove that that the minor repair, or modification does not effect the flutter of a rudder ?

The wording of this would tend to make the most minor thing a major modification.

yet we know any A&P can strip and repaint re-balance the flight control and be legal even if the balance has changed.

As was mentioned, my addition of the flasher to my rudder or a trim tab on any flight control, is that a minor or a major modification? and thus how do you show that it does not effect the flutter of the control.

I see aircraft all the time that have trim tabs added and no paper work to cover the modification, where do we draw the line ?
 
Ted DuPuis said:
No. Your petition to the FAA would be for the DER/DAR to be delegated authority to approve said plan. You could write it if you felt up to it.
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That is what I was thinking to start, I will call the FAA on monday and ask what /how to do this.
 
Tom-D said:
To take this a step higher, FAR 43-A says,

(xiii) Changes to the wing or to fixed or movable control surfaces which affect flutter and vibration characteristics.

How would you prove that that the minor repair, or modification does not effect the flutter of a rudder ?
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by balancing it IAW manufacturers specifications?

The wording of this would tend to make the most minor thing a major modification.

yet we know any A&P can strip and repaint re-balance the flight control and be legal even if the balance has changed.
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If it had been re-balanced, the balance is the same. The weight might be different.

As was mentioned, my addition of the flasher to my rudder or a trim tab on any flight control, is that a minor or a major modification? and thus how do you show that it does not effect the flutter of the control.

I see aircraft all the time that have trim tabs added and no paper work to cover the modification, where do we draw the line ?
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The flasher would be a balance thing, the trim tab would probably be more than that. But still a balance thing as well. Both (flasher, and/or trim tab) affecting the balance, and thus the flutter characteristics, would most likely be a major alteration.
I would think you should have a handle on this already.

I
 
bluerooster said:
I would think you should have a handle on this already.
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Like I've said, my aircraft light is not the subject aircraft.

You make the assumption that the balance of the flight control will meet the flutter requirements. it will not.

Call your PMI, see if they will sign off a 337 after a modification when you only rebalance the control with in the manufacturers spec.

the light on my rudder is on center with the hinge line, and rotates with the rudder and is not in the airstream to effect the airflow over the control surface. The rudder skin was not cut, no hardware was added, nothing was added to modify the rudder in any other way except to add 2 oz to the entire weight of the rudder.
 
Tom-D said:
Like I've said, my aircraft light is not the subject aircraft.


You make the assumption that the balance of the flight control will meet the flutter requirements. it will not.

Call your PMI, see if they will sign off a 337 after a modification when you only rebalance the control with in the manufacturers spec.

the light on my rudder is on center with the hinge line, and rotates with the rudder and is not in the airstream to effect the airflow over the control surface. The rudder skin was not cut, no hardware was added, nothing was added to modify the rudder in any other way except to add 2 oz to the entire weight of the rudder.
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Then it would seem that, lacking any other info. The safest way would be wind tunnel, and flight test. Or "ride the coattails, of someone else who already did it.
 
bluerooster said:
Then it would seem that, lacking any other info. The safest way would be wind tunnel, and flight test. Or "ride the coattails, of someone else who already did it.
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Or consider it a minor mod.
 
Tom-D said:
Or consider it a minor mod.
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The light would be a minor mod, done the way yours is.
But a trim tab (where none existed before) on the otherhand.... A minor mod?
 
Tom-D said:
Or consider it a minor mod.
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Well, you could always propose that it is a minor mod and see if the FSDO accepts it.

(I love the FAA definitions of minor and major changes)
 
Bob Noel said:
Well, you could always propose that it is a minor mod and see if the FSDO accepts it.

(I love the FAA definitions of minor and major changes)
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Why would you give them a chance to say no?

Once they are onto you ------> They are onto you.
 
Tom-D said:
Why would you give them a chance to say no?

Once they are onto you ------> They are onto you.
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That, sir, is the conundrum.
Don't give them the chance to say "no". consider it a minor mod.
Then something happens, totally unrelated to the mod, but the logs get perused by the powers that be, and it comes to light that there has been a mod which they consider to be a major mod, but logged as minor, or not logged at all.
Then what?
 
Tom-D said:
Why would you give them a chance to say no?

Once they are onto you ------> They are onto you.
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Who decides if a mod is minor?
 
bluerooster said:
The guys going through the logs after a calamity? (Even though the calamity had nothing to do with the mod.)
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Unless there is a circumstance indicating the mod was the problem.. probably no.
 
bluerooster said:
That, sir, is the conundrum.
Don't give them the chance to say "no". consider it a minor mod.
Then something happens, totally unrelated to the mod, but the logs get perused by the powers that be, and it comes to light that there has been a mod which they consider to be a major mod, but logged as minor, or not logged at all.
Then what?
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Lots of items to vary that process.
 
I worked on several projects at work where we paid for a 3rd party to develop an STC or paid a STC holder to change their STC to include installation on our airplanes.

If you pay a DER you probably get someone that already has a business relationship with folks at the FAA ACO (Aircraft Certification Office).

I've been toying with the idea of trying to become a consulting DER myself, still not sure how much value there is in it. I have to see what I run into getting alterations approved on my own airplane.

I don't think a DER can approve an STC. I know our company DERs can approve certain Major Repairs, but cannot approve STCs.

A DER can write 8110s to approve data, and recomend approval of the STC package, but the final approval is still the FAAs.

There are a number of other approval authorities like Designated Alteration Station (DAS), they can approve an STC on behalf of the FAA. They typically have several project reviews with the FAA in the course of the developing a package, so the FAA is in the loop.

Sometimes, if the installation is very similar to one already certified, the approval process is much shorter. It's got to be documented correctly.
 
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