FAA grounds all B-17E,F, & G models

[RCS]

The FAA recently issued a directive to ground all Boeing B-17E, F, and G models over concerns related to wing issues.

There are 18 registered B-17's in the USA and which three are still flying. there is one in operation in the UK

[limpetmine]

It was bound to happen. These old birds can't fly forever.
Remember the N9M catastrophe. Last survivor of 4 built, and now gone, along with a seasoned pilot. My son and I were able to see it at the Chino Air Museum on a father son trip 1999.

2019 Northrop N-9M crash - Wikipedia

[browningautorifle]

Yes, too bad but they're 85 years on now? How much longer can they safely fly? More important to have them prefect on the ground than maybe destroying things when they crash.

[oldfoneguy]

Yes, too bad but they're 85 years on now? How much longer can they safely fly? More important to have them prefect on the ground than maybe destroying things when they crash.

The B17 can stay flying in the same way the B52 and the A10 is still in active service Jim. Regular inspection and maintenance schedules that are strictly adhered to and they can fly conceivably forever.
I find it very hard to swallow that after 85+ years they suddenly find a defect in the design of the wing spar grounding all flying examples? A week before the Memorial Day air shows kick off? Not trying to do wrong by the site here but it reeks of dirty politics.

[browningautorifle]

I find it very hard to swallow that after 85+ years they suddenly find a defect in the design of the wing spar

OK, possibly dirty pool as you say. I do know about the B52, have seen them do runs over me. I know there's guys flying aircraft their grandfathers flew.

[Bob Womack]

Going with what I've heard from the B-17 group on Facebook: This isn't a wing spar issue, it is a wing attachment issue. Apparently the EAA's Aluminum Overcast was discovered to have a two-inch gap between the port wing and root while out on tour! To find the problem they had to disassemble the plane and ship it home. They told the FAA what they discovered and the FAA issued an Advanced Directive for the rest of the survivors involving disassembly, advance imaging, and remediation if necessary. It isn't a hard inspection.



These are the parts in question, forward mounting plates and pins. The arrows point out where the pieces were relieved at service depots when they wouldn't reassemble after a service. Apparently one side had to be heated and the other had to be frozen before it could be done and some service depots didnt' know so the parts griped too much to be reassembled. The result over time could be hidden fracturing leading to the wings becoming loose! The parts aren't hard to find or fabricate. Aluminum Overcast and Sentimental Journey have been inspected and are back in the air already. Others are completing the process right now. The directive indicates that this may end up being a recurring 120 mo/2500hr inspection cycle for B-17s. More, HERE.

Bob

[GeeRam]

Going with what I've heard from the B-17 group on Facebook: This isn't a wing spar issue, it is a wing attachment issue. Apparently the EAA's Aluminum Overcast was discovered to have a two-inch gap between the port wing and root while out on tour! To find the problem they had to disassemble the plane and ship it home. They told the FAA what they discovered and the FAA issued an Advanced Directive for the rest of the survivors involving disassembly, advance imaging, and remediation if necessary. It isn't a hard inspection.

https://www.milsurps.com/images/impo...71269566-1.jpg

These are the parts in question, forward mounting plates and pins. The arrows point out where the pieces were relieved at service depots when they wouldn't reassemble after a service. Apparently one side had to be heated and the other had to be frozen before it could be done and some service depots didnt' know so the parts griped too much to be reassembled. The result over time could be hidden fracturing leading to the wings becoming loose! The parts aren't hard to find or fabricate. Aluminum Overcast and Sentimental Journey have been inspected and are back in the air already. Others are completing the process right now. The directive indicates that this may end up being a recurring 120 mo/2500hr inspection cycle for B-17s. More, HERE.

Bob

Those items in the photo posted are the items related to the previous AD issued back in 2001.

The new AD is in relation to the bolts that fix through the steel spigot that fits inside the tapered alloy spar tube, the end of this spigot is what attaches to those steel plates.

This updated article from aerovintage shows photo's from the items in a current dismantled B-17 being restored.

https://www.aerovintage.com/2023/05/...e-may-25-2023/

The big potential problem, will be if any NDT shows up any corrosion or cracks in the tapered ally tube section, rather than the steel spigot, as its impossible to reproduce these tapered spar tubes.
The steel spigot can be replaced, although to do so means taking the wings off.

[CINDERS]

So how do they go with the Spitfires main spar as its assembled then cranked at which point you cannot separate it to inspect it!

[GeeRam]

So how do they go with the Spitfires main spar as its assembled then cranked at which point you cannot separate it to inspect it!

Spitfire spar beams can be reproduced, in fact pretty much everything for a Spitfire can, or has been reproduced, and is a very different form of construction.

[jond41403]

Please forgive my ignorance but why is it impossible for them to reproduce the tapered spar tubes?