B-17G Aluminum Overcast Update

[aerovin2]

I just posted information from an update I received from the EAA about the status of B-17G Aluminum Overcast (44-85740, N5017N). Not a whole lot of new information but it does provide an authoritative update.

https://www.aerovintage.com/home/blog/

[terveurn]

????

How does this differ from the AD grounding all the flyable B-17's until the wing attachment points were visually inspected and modified to prevent this type of cracking.

Did not the EAA ship have this AD complied with and if so, is this a new problem for the airworthy aircraft.

[Chuck Giese]

????

How does this differ from the AD grounding all the flyable B-17's until the wing attachment points were visually inspected and modified to prevent this type of cracking.

Did not the EAA ship have this AD complied with and if so, is this a new problem for the airworthy aircraft.

The AD does not apply to the shear structure, only the upper and lower spar tubes at the wing terminal bolt hole area. The AD is concerned with dissimilar metals corrosion, steel wing terminals inserted into aluminum spar tubes. In order to satisfy the AD, it is necessary to remove the wing terminals, coat them with an anti-corrosion compound, and then re-insert them. There is an AMOC for periodic eddy current inspection of all of the bolt holes (looking for cracks), instead of the terminal pull (which requires a wing pull).

[terveurn]

????

How does this differ from the AD grounding all the flyable B-17's until the wing attachment points were visually inspected and modified to prevent this type of cracking.

Did not the EAA ship have this AD complied with and if so, is this a new problem for the airworthy aircraft.

The AD does not apply to the shear structure, only the upper and lower spar tubes at the wing terminal bolt hole area. The AD is concerned with dissimilar metals corrosion, steel wing terminals inserted into aluminum spar tubes. In order to satisfy the AD, it is necessary to remove the wing terminals, coat them with an anti-corrosion compound, and then re-insert them. There is an AMOC for periodic eddy current inspection of all of the bolt holes (looking for cracks), instead of the terminal pull (which requires a wing pull).

Again, I thought the EAA B-17 had this AD complied with.

Is this a different problems with the attach points, or just a continuation with the previous AD.

Does this mean all the flyers will have a new expensive inspection to deal with ?

[aerovin2]

The AD can be found here: https://www.federalregister.gov/docume ... -airplanes

The AD only addresses the wing side of the wing attach….not the fuselage side. The AD specifies inspections of the terminal wing fittings and the spar tubes (two per spar, upper and lower; four per wing) and the eight bolts holding each of the assemblies together.

So, the AD does not address the problem found on Aluminum Overcast. The AD has no doubt been complied with by the EAA or the airplane would not have been flying.

As to whether the FAA will determine this is a problem that could be further widespread…time will tell. No rumblings heard that way yet but I wouldn’t expect any at this point. The good thing is that the EAA crew found it themselves and are proactively addressing it.

[terveurn]

The AD can be found here: https://www.federalregister.gov/docume ... -airplanes

The AD only addresses the wing side of the wing attach….not the fuselage side. The AD specifies inspections of the terminal wing fittings and the spar tubes (two per spar, upper and lower; four per wing) and the eight bolts holding each of the assemblies together.

So, the AD does not address the problem found on Aluminum Overcast. The AD has no doubt been complied with by the EAA or the airplane would not have been flying.

As to whether the FAA will determine this is a problem that could be further widespread…time will tell. No rumblings heard that way yet but I wouldn’t expect any at this point. The good thing is that the EAA crew found it themselves and are proactively addressing it.

Thanks Scott - that is the information I was seeking.

Now to see if the FAA will mandate another expensive wing inspection on the flyable B-17 fleet

Dave