Warbird Information Exchange

Edited

Announced on Facebook, B-17G Yankee Lady has been voluntarily grounded. They didn't get into specifics, but it sounds like it was in anticipation of an upcoming FAA AD.

While this has turned out to not be because of an actual issue found, it does bring up a problem facing the B-17 community. The spars themselves have been a real nightmare for those restoring Forts. They're a nightmare to manufacture. They're a square tube with a wall thickness that tapers from one end to the other, with all of the taper being on the inside of the tube. So far, nobody in the US has been found that can manufacture these. I was speaking to Mike Kellner a number of years ago, he said the tooling to make these was sold to China. He says he was leery about having them make the tubes because China is famous for sending out wrong alloys and claiming them to be correct. I hope a solution can be found, we're quickly running low on flyable B-17s.

I just added a post to my aerovintage.com site that provides a bit of an overview.

https://www.aerovintage.com/2023/04/15/new-b-17-wing-ad-forthcoming/

_________________
Scott Thompson
Aero Vintage Books
http://www.aerovintage.com
WIX Subscriber Since July 2017

Thanks Scott, your post is, like always, well done and very informative. I've been looking into the spars for close to a decade after a conversation with Mike Kellner. They are fairly complicated and tough/ not currently possible to replicate. Hopefully, someone can be located who can manufacture the various parts needed to get the fleet back in the air.

Yep, all B-17's worldwide are about to be grounded. The AD is forthcoming and operators have been notified to fly their B-17's to whatever location they wish before the AD becomes effective and the aircraft can't fly. My understanding is this all goes back to "Aluminum Overcast" originally and then "Yankee Lady", which had the same or similar issues. The FAA is about to publish this emergency AD shortly.

Unfortunately, there is a high probability that we won't see any B-17's fly this year after the AD is issued.

A few years ago, the Erickson Aircraft Collection replaced the fuselage side structure wing attachments on their B-17, which I presume is the same area of work/attention being addressed here? It appears that this same work has been underway over the last year on the Mid America Flight Museum's B-17, which is being worked on at the Erickson Aircraft Collection facilities.

Hard to believe that with today's technology we can't replicate what was made 80 years ago.

bomberfan indicates the tooling was sold to China. They bought the tooling in hopes of cornering the B-17 spar market? Does it have another use?

_________________
45-47=-2

I'm assuming it has other uses, but I'm not 100% sure. I'm going off what Mike told me.

For the metallurgist & engineering minds, is the internal taper intentional, or the result of the extrusion process? And does it serve a purpose? Finally, is this type of part seen on any other Boeing (or other) products?

Ken

_________________
"Take care of the little things and the big things will take care of themselves."

Many (many!) years ago, I was taken on a tour of British Aluminium's extrusion/drawing plant in Redditch, UK.

One discussion centered on tapered yacht masts. From memory, and it's not far short of 50 years ago, they used aluminium dies which wore and became larger as the tubes were pulled through them thus creating the taper.

I suspect the issue is not a matter of technology but a matter of financial sense. The cost to make the tooling can only be offset by roughly ten customers worldwide. Plus the new spars will last roughly fifty years before new ones would be needed again. The numbers just don't work. Now maybe we will all get lucky and there will be rich person out there somewhere who does not care about the lack of financial sense and will step up and do it anyway. Always a possibility in the warbird community. Hopefully it wlll happen.

The B-17 group may need to get together and figure out an AMOC (alternative means of compliance). It was done for Mallard centre sections.

I wonder if they could be enticed to sell them back if they still exist? I have wondered if that P-61 they have could be bought back also.

Everything has a price.

Interesting, I hadn't heard of any existing B-17 tooling before. I assume it wasn't left over from the war, so did someone recreate it?


I remember seeing a video that the Champaign Aviation Museum was repairing the spars they had by splicing in a new solid inner core.[1] Is it possible that something similar could be done in this situation?

_________________
Tri-State Warbird Museum Collections Manager & Museum Attendant

Warbird Philosophy Webmaster

Didn't the old Evergreen museum's B-17G (now owned by Collings) have the same issues? How'd they fix them?

_________________
Life member, 91st BG Memorial Association
Owner, 1944 Willys MB #366014
Former REMF (US Army, O3)