Spar Cap Replacement

[A64Pilot]

17 minutes ago, 47U said:

This statement is just a bit open-ended.  

Sounds like a catch-all statement allowing the FAA to hold a mechanic accountable for anything and everything.  

Yep, they intentionally do something similar in most FAR’s and I believe are often intentionally vague, requiring the mechanics or IA to form an opinion. That’s the Catch 22. I don’t think it’s as much to hold a Mechanic responsible as it is to absolve FAA responsibility, truthfully it’s exceedingly rare that they go after a mechanic. It’s also why I believe there are so many AC’s, being advisory only and not a regulation absolves the FAA, but also gives them the power to in effect hold you to an AC without having to go through the hassle of making a regulation, many AC’s in my opinion wouldn’t make it through the regulation process.

Years ago someone higher up in the FAA told all the inspectors that they could be personally held responsible for their actions as in sued and lose property etc., that when field approvals went to essentially forget about it.

They also very often in an attempt to close loop holes sometimes get very specific, which at least as often as not opens more loop holes, opens the door for “Well it doesn’t say I can’t do this or that”

FAA is one of the largest and most deeply rooted Bureaucracies, and once you a accept that the purpose of a Bureaucracy isn’t what it’s mission statement is, it’s to foster growth of and to protect the Bureaucracy.  If you accept that then a lot of their actions begin to make sense.

Edited February 18 by A64Pilot

[Pinecone]

14 hours ago, A64Pilot said:

Years ago someone higher up in the FAA told all the inspectors that they could be personally held responsible for their actions as in sued and lose property etc., that when field approvals went to essentially forget about it.

That does not jive with the Federal Tort Claims Act.

 

[geoffb]

what model M20 are we talking about here?

[geoffb]

TKS gets all over the interior of the airframe.  Gets in the wings from the under wing inspection panels, gets in up under the belly skins, runs down the vertical into the tail cone.  If it was at all corrosive, the plane would be junk by now in the 500 hrs since TKS install.

 

[A64Pilot]

7 hours ago, Pinecone said:

That does not jive with the Federal Tort Claims Act.

 

I didn’t think it logical myself, but more than one inspector told me it, it even got one of my inspectors worried at the plant.

I finally told him that not trying to be ugly but he’s not getting sued, he doesn’t have enough assets to even whet a Lawyers appetite, he still worried though

[A64Pilot]

I know very little about TKS myself, but these guys claim that unlike ground de-icings, TKS isn’t corrosive.

I didn’t think the ground stuff was either

https://www.cav-systems.com/tks/

[Pinecone]

18 hours ago, geoffb said:

what model M20 are we talking about here?

M20J

Avionics are original with addition of a 430

[Pinecone]

15 hours ago, A64Pilot said:

I didn’t think it logical myself, but more than one inspector told me it, it even got one of my inspectors worried at the plant.

I finally told him that not trying to be ugly but he’s not getting sued, he doesn’t have enough assets to even whet a Lawyers appetite, he still worried though

I had some interactions with a DOJ lawyer about FTCA.  And basically, if you are working within the scope of your job, you are not personally liable.  And since almost every job description includes "other duties as assigned," as long as you are within what you were told to do, you are covered.

[Pinecone]

15 hours ago, A64Pilot said:

I know very little about TKS myself, but these guys claim that unlike ground de-icings, TKS isn’t corrosive.

I didn’t think the ground stuff was either

https://www.cav-systems.com/tks/

I have heard that as TKS fluid ages, it becomes acidic and corrosive.

It is pretty much alcohol and ethylene glycol (car antifreeze).

[A64Pilot]

Normally if you heat a fluid it becomes more reactive, that is it accelerates corrosion significantly when hot.

So if car antifreeze was corrosive surely given a couple of decades it would destroy modern aluminum Auto engines and especially radiators as they are thin walled?

Last Summer my 2005 Mazda Speed Miata radiator started leaking, the seals on the plastic tanks were why, it’s common on old Miata’s. Anyway I looked inside the aluminum radiator, the metal was just as bright and clean as the new radiator was, so no corrosion at all in 19 years. I do flush and change coolant every three years, probably excessive, but cheap and easy to do. But it seems that at least the old Prestone green isn’t corrosive to aluminum?

Edited February 19 by A64Pilot

[Josiah Murphy]

On 2/17/2025 at 2:53 PM, Mark89114 said:

was wondering the same thing....I just see flaky paint......

I am just an internet expert.....

The grey oval in the center of the picture, located on the spar flange/ doubler is the corrosion. The alcad coating has flaked off and underneath/inside the grey hole is intergranular corrosion, from the surface it doesn't look terrible, but it's deep corrosion that that makes that particular part unrepairable and must be replaced. 

[N201MKTurbo]

Corrosion is almost always an electro-chemical process. It requires an electrolyte. It has to transfer ions from one place to another. Water is an excellent electrolyte. Most alcohols are poor electrolytes. Most organic chemicals like oil and gasoline are poor electrolytes. So, you cannot just say that fluids are corrosive. While alcohols are not corrosive, they absorb water which is.

[Pinecone]

10 hours ago, A64Pilot said:

Normally if you heat a fluid it becomes more reactive, that is it accelerates corrosion significantly when hot.

So if car antifreeze was corrosive surely given a couple of decades it would destroy modern aluminum Auto engines and especially radiators as they are thin walled?

Last Summer my 2005 Mazda Speed Miata radiator started leaking, the seals on the plastic tanks were why, it’s common on old Miata’s. Anyway I looked inside the aluminum radiator, the metal was just as bright and clean as the new radiator was, so no corrosion at all in 19 years. I do flush and change coolant every three years, probably excessive, but cheap and easy to do. But it seems that at least the old Prestone green isn’t corrosive to aluminum?

There were additives to prevent corrosion.  In the old days, that was one reason why you flushed the system every so often and replaced the anti freeze.