Piper SB 1244B mystery to me

[jeffs chips]

Roy Williams of Airframe Components gives probably the very best explanation of the mechanical implications and repair of Piper SB 1244B.

Maybe someone can clarify, though, when at minute 3 he is showing some mated aluminum with steel plating which has severely degraded around the area of the wingspar and because of how it is placed together in the assembled spar, it looks like it's decomposing from the inside-out. I fail to see how anything other than a pulled wing with interior inspection could even detect this and yet, people seem to think that boroscope into the area of the spar is sufficient to detect a failing spar.

I'm not a mechanic so can someone please clear this up for me? It would appear that any Piper aircraft so affected by the SB really should have the wing pulled and examined and anything short of that might be asking for trouble. I hear that's a costly job.

Thanks for any enlightenment.

 

[Bell206]

so can someone please clear this up for me?

Not all corrosion equals a loss of structural integrity. They've determined in 1244 that unless the indicated corrosion meets the defined limits requiring rework, the spar remains structurally serviceable.

 

[jeffs chips]

Thanks @Bell206. The troubling oversight - at least from what I'm seeing and I'm probably in error on this - is that you can't see the actual corrosion, at least in the example Roy gives in that video, with a boroscope. The entire wing must be removed and the plates of aluminum and steel at the joint must be pulled apart to view *inside* the two sides of the dissimilar metal, which corrodes at a faster rate apparently than similar metal plates held together. I would agree you are correct if you can view the corrosion, but the corrosion he is showing is totally unviewable from the outside.

Watch the video at minute 3.

 

[Bell206]

The troubling oversight - at least from what I'm seeing and I'm probably in error on this -

You're making a determination based solely on what you "see" and not what is actually there. As I mentioned earlier, not all corrosion equals a structural issue which is what Piper has determined also.

but the corrosion he is showing is totally unviewable from the outside. Watch the video at minute 3.

I watched it. What do you think is between any other critical steel to aluminum riveted parts on the aircraft? A bit of theatrics on his part to take it to that level.

 

[jeffs chips]

I suspected that was the case. . .