L-19 Leaf spring installation

[flyingredyeti]

So, I've seen reference, on this forum, to the heavy-duty L-19 spring being installed as an upgrade on the 170. My question is, does anyone have approved/accepted data allowing this alteration? I have found no STC for it, and Univair only lists the spring set (P/N L19TWS), as applicable to the L-19. Are we talking about different spring sets?

[flyingredyeti]

Okay, I'll jump-start this by adding a bit more. Among other references on the forum to this installation, I've seen Bruce & George debating the reasoning & results of using this spring, and I've seen the modification referred to as a minor alteration. However, this is definitely not a minor alteration, nor is the substitution of the stock bolt for the L-19 eyebolt. Why? Because, per Part 43 appendix A, any alteration to landing gear is a major alteration.

That said, knowing this is a major alteration to the Cessna 170, where is the basis or justification for installing it?

I can think of a few reasons not to.

[bagarre]

It sounds like you're answering your own questions.

No one is going to stop you from hiring a DER and filing a 337 for replacing the tailwheel main spring from that of an L-19 if that's what you want to do.

The other option is to source a 170 tailwheel spring.

[flyingredyeti]

You are correct David, but finding approval for myself is not the intent of the question. I am challenging the premise for making such an alteration, and would like to hear what people have to say in response.

-joshua

[bagarre]

Oh. You're trying to start an argument.
I understand now.

[flyingredyeti]

Sure, but a productive argument. I believe many decisions in aircraft maintenance are based on assumptions, 2nd-hand information, and carry-over practices, from other industries, that don't necessarily apply. So, why not bring such topics out in the open for clear discussion?

-joshua

[bagarre]

There is no approval for installing an L-19 main spring on a 170.
Nor is there approval for installing an L-19 eye bolt on a 170.

Continue your sermon.

[wingnut]

Okay, I'll jump-start this by adding a bit more. Among other references on the forum to this installation, I've seen Bruce & George debating the reasoning & results of using this spring, and I've seen the modification referred to as a minor alteration. However, this is definitely not a minor alteration, nor is the substitution of the stock bolt for the L-19 eyebolt. Why? Because, per Part 43 appendix A, any alteration to landing gear is a major alteration.

That said, knowing this is a major alteration to the Cessna 170, where is the basis or justification for installing it?

I can think of a few reasons not to.

You are inserting words into the regs, which makes a conversation with you impossible

[flyingredyeti]

"Title 14: Aeronautics and Space
PART 43—MAINTENANCE, PREVENTIVE MAINTENANCE, REBUILDING, AND ALTERATION
Appendix A to Part 43—Major Alterations, Major Repairs, and Preventive Maintenance

(a) Major alterations—(1) Airframe major alterations. Alterations of the following parts and alterations of the following types, when not listed in the aircraft specifications issued by the FAA, are airframe major alterations:

(i) Wings.

(ii) Tail surfaces.

(iii) Fuselage.

(iv) Engine mounts.

(v) Control system.

(vi) Landing gear.

(vii) Hull or floats.

(viii) Elements of an airframe including spars, ribs, fittings, shock absorbers, bracing, cowling, fairings, and balance weights.

(ix) Hydraulic and electrical actuating system of components.

(x) Rotor blades.

(xi) Changes to the empty weight or empty balance which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft.

(xii) Changes to the basic design of the fuel, oil, cooling, heating, cabin pressurization, electrical, hydraulic, de-icing, or exhaust systems.

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

[bagarre]

Hey look,
he can copy and paste too.

[flyingredyeti]

David, I would like to hear your feedback on the topic too, if you have any. Otherwise, I don't see why you keep posting, as you haven't said anything yet.

[bagarre]

Neither have you.
All you're doing is trolling the forum looking for a fight.

[flyingredyeti]

All right man, then please feel free to ignore my posts on move on, as I will do with your hostile replies to mine.

[wingnut]

"Title 14: Aeronautics and Space
PART 43—MAINTENANCE, PREVENTIVE MAINTENANCE, REBUILDING, AND ALTERATION
Appendix A to Part 43—Major Alterations, Major Repairs, and Preventive Maintenance

(a) Major alterations—(1) Airframe major alterations. Alterations of the following parts and alterations of the following types, when not listed in the aircraft specifications issued by the FAA, are airframe major alterations:

(i) Wings.

(ii) Tail surfaces.

(iii) Fuselage.

(iv) Engine mounts.

(v) Control system.

(vi) Landing gear.

(vii) Hull or floats.

(viii) Elements of an airframe including spars, ribs, fittings, shock absorbers, bracing, cowling, fairings, and balance weights.

(ix) Hydraulic and electrical actuating system of components.

(x) Rotor blades.

(xi) Changes to the empty weight or empty balance which result in an increase in the maximum certificated weight or center of gravity limits of the aircraft.

(xii) Changes to the basic design of the fuel, oil, cooling, heating, cabin pressurization, electrical, hydraulic, de-icing, or exhaust systems.

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

The above copy/paste does not contain the word "any" as you suggest in a previous post. If you are truly interested in a productive discussion, and truly believe the alteration you are describing in this thread is a major alteration, then I'll participate. However, I will not administer medicine to the dead. If you are only interested in being right, find another sandbox.
The following links are by no means intended to offer definitive 'proof', but as a starting point please read the content in these links. Then also follow the referenced material and read it as well.

https://www.aopa.org/news-and-media/all ... lterations
https://www.aopa.org/news-and-media/all ... ons-part-2

There is also a very good publication entitled "Northwest Mountain Region, Guide to Aircraft Alterations". I have a paper copy, but I can't find it online. I can scan the section discussing major versus minor and post when I have time.
Obviously my opinion differs from yours. If I were to only reference FAR43 Appx A, I would have no choice but to agree with you. Fortunately there exist much more information. This is a beginning.

[lowNslow]

Del, thanks for the links both good reads. As stated in the article the real problem is at the regional level where interpretations vary wildly. My local FSDO thinks that installing any avionics is a major alteration. I still haven't figured out how they came up with this after reading the FARs.

I have also found the "Northwest Mountain Region, Guide to Aircraft Alterations" a very good read, tho it looks like the FAA took it down off there site - I just happen to have a pdf version.