Fretting question

jaybee

jaybee

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jaybee
So how bad does fretting ( the black streaks from rivets ) have to be before you would -

  • Devalue the airplane for sale?
  • Not fly the thing?

I ask because with my limited current budget I thought about purchasing a 150 to fart around in a time or two that my friend owns. I learned to fly in the plane. Its always showed signs of fretting however, never found a loose rivet mind you but the black streaks are there.

Thinking back on my Private level training, I wonder how dumb I may have been to get in the thing like that. :eek:

I can't imagine drilling out and rebucking every rivet on a 150 to be worthwhile :dunno:
 
Ahhhh...the smoking rivet. Prior structures troop here. May be fun to shoot some rivets. I guess a good inspection is in order.
 
Corpsmaide said:
Ahhhh...the smoking rivet. Prior structures troop here. May be fun to shoot some rivets. I guess a good inspection is in order.
Click to expand...

I'm assuming, not being an A&P, that would entail drilling out the offending rivets ( which in this case are all the rivets on some of the panels ) and checking to see if the hole or substructure is elongated ?

As I said earlier hardly seems worth while on a 150 :wink2:
 
I seriously doubt you're looking at that many "smoking" rivets, the plane just probably has not been washed in a long while. The aerodynamics of a standard button head rivet cause dirt and grime to collect on the lee side.
 
Silvaire said:
I seriously doubt you're looking at that many "smoking" rivets, the plane just probably has not been washed in a long while. The aerodynamics of a standard button head rivet cause dirt and grime to collect on the lee side.
Click to expand...

Agree. Fretting is usually caused by minute vibration between two surfaces with high contact pressure like between a fan blade and a disc in a turbine engine.

Cheers
 
Is the airplane painted or polished aluminum? Reason I ask is that polishing can leave a black residue that looks similar to smoking rivets...

:needpics:
 
How many "smoking rivets" are you talking about? A couple? A couple thousand?
 
It is painted.

It has been over course of several years, so it has been through a wash cycle or two.

While I admit to not being an expert I'm 99% sure I know what fretting is and what it looks like :)

Looked on my hard drive, sorry no pics readily available.

Shoot, I don't know - let's say there are 10000 total on the whole plane then maybe 100 total on the whole plane :dunno:

Either way, even if I was incorrect about it being fretting the question and the advice would still be the same.

IF I was looking at that much actual fretting -
  • How much before it devalues the plane ?
  • How much before it becomes unsafe ?
Can we please discuss the topic rather than my technical prowess :wink2:
 
Just a guess without looking but the airplane was probably treated with a Corrosion Inhibiting Compound (CIC) like ACF-50 or Corrosion X which is similar to a light oil spayed all over the inside of the aircraft structure. Aircraft tend to exhibit the symptoms you describe afterwards.

And it shouldn't be a huge deal breaker but again, without pics it's hard to say.
 
jaybee said:
IF I was looking at that much actual fretting -
  • How much before it devalues the plane ?
  • How much before it becomes unsafe ?
Can we please discuss the topic rather than my technical prowess :wink2:
Click to expand...

If you are looking a 100 "actual" fretting rivets then you are looking at a very serious structural problem. Rivets don't just come loose and begin to fret, there is an underlying cause. Where exactly are these smoking rivets located? Are there cracks in the skin?
 
Yeah, usually only one here or there unless there is an underlying cause, such as the location of the flaps of a twin in the prop wash.
 
As part of the recent work on the 310, we ended up fixing a decent number of smoking rivets on the top of one of the wings. Probably a couple dozen total, I really don't remember the exact number. I can't remember what it cost, but it really wasn't too bad. Now this is compared to 310 expenses. On a 150, it might double the cost of your annual. Sounds like a lot when you put it that way, but in raw dollars not a ton.

Our A&P saw it at annual, but because of schedule constraints there wasn't time to fix them then. I asked him about it as a safety concern, and he said "Definitely not at this point - let's just do it when you get back." So I went on a short jaunt from Ohio to Belize and back, and then he pulled the plane in to have them fixed.

Talk to an A&P, find out how much it would cost to fix. Keep in mind you may have some others occur throughout your ownership. Consider whether you're interested in doing some owner-assisted work to help out on it.
 
If I remember correctly off the top of my head it was a couple of panels on top of the wings. Without an access cowl nearby I assume I would need to also pull the panels next to the panel needing work as well as the fuel tanks I assume to get in there properly.

More of a curiosity question more than anything. If I were to buy it I would definitely bring it up.

I definitely was not sure at what point it would become a safety issue.
 
jaybee said:
Shoot, I don't know - let's say there are 10000 total on the whole plane then maybe 100 total on the whole plane :dunno:

Either way, even if I was incorrect about it being fretting the question and the advice would still be the same.

IF I was looking at that much actual fretting -
  • How much before it devalues the plane ?
  • How much before it becomes unsafe ?
Can we please discuss the topic rather than my technical prowess :wink2:
Click to expand...
Reason I ask is a couple here and there, is a lot different than a couple hundered. A hundered is enough to look a little deeper, not necessarily devalue the airframe. I would say that is unusual to have that many. Make sure they are not "Tipped" which would be an indication of overstress. How many till it becomes unsafe? A lot, but the real answer is it depends. Are they all localized, what area are they in etc...

I don't think anyone can give you a solid answer without seeing it.

Good for you for asking
 
flyingmoose said:
Reason I ask is a couple here and there, is a lot different than a couple hundered. A hundered is enough to look a little deeper, not necessarily devalue the airframe. I would say that is unusual to have that many. Make sure they are not "Tipped" which would be an indication of overstress. How many till it becomes unsafe? A lot, but the real answer is it depends. Are they all localized, what area are they in etc...

I don't think anyone can give you a solid answer without seeing it.

Good for you for asking
Click to expand...

That was the main concern. I'm not trying to sell my buddy down the river but I know for certain while learning to fly with him that we took off over gross a couple of times.


Also I just wanted to say before anyone possibly gets on a soapbox that when you are new to something and someone with 30 years of experience says its fine :dunno: I'm not going to argue.

I'm not so naive to think that overloading didn't cause some kind of stress somewhere. I did want to talk about the actual airframe though, not the people - thank you.

I don't think anyone can give you a solid answer without seeing it.

Ill see what I can do about that
 
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