Yankee Lady grounded

[whistlingdeath77]

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.

This information is incorrect

[OD/NG]

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.

This information is incorrect

O.K., please set the record straight then. I want to be as accurate as possible.

[menards]

I was speaking to Mike Kellner a number of years ago, he said the tooling to make these was sold to China.

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?

The B-17 group may need to get together and figure out an AMOC (alternative means of compliance).

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?

It may be more cost effective to go to the static airframes and pull out and/or swap airworthy spars for one that will never fly again....

[YAF340]

I have flown with the Yankee Lady for the last 17 years. We are not aware of any spar problem with her at this time. We are on hold until we see what the AD, which we know is coming says. It just does not make any sense to burn a bunch of fuel to get the Pilots ready and have to park her. Joe

[JohnB]

Once it's clear what the issue is, it sounds like a project for the B-17 owners consortium.

Share the cost of tooling up the repair and getting a bulk (very relativity speaking) buy.

I had thought about using the sparsu from static aircraft, but you would be looking at a lot of labor for spars of unknown quality. A lot of the parked ships led hard lives as fire bombers or have been outdoors for the past 78 years.

Last edited by JohnB on Sat Apr 22, 2023 2:29 pm, edited 1 time in total.

[bomberfan]

I have flown with the Yankee Lady for the last 17 years. We are not aware of any spar problem with her at this time. We are on hold until we see what the AD, which we know is coming says. It just does not make any sense to burn a bunch of fuel to get the Pilots ready and have to park her. Joe

Thanks for chiming in Joe, you and I have spoken multiple times at Thunder, Oshkosh and AirExpo in MN. I started this thread with the mention of spar problems because that's what was reported on Facebook. I'm guessing this means that was incorrect? If so, do you know what sparked this latest AD? Was it the issues with Aluminum Overcast? Or something else?

[YAF340]

I don't have any direct information at this time and won't be the first to know at our Hangar. What I've been told, it started with Aluminum Overcast and things that were found on a couple others that are under restoration. How long we'll be down depends on what the AD says we have to do. Joe

[phil65]

https://www.eaa.org/airventure/eaa-airv ... tz5D7KL7kw

Phil

[lucky52]

On " Aluminum Overcast ", is the problem with the wing attach fittings on the fuselage or something to do with the wing spars themselves?

[JohnB]

If the spars are that difficult to reproduce, what are the quasi-"new build" B-17s using?
Or did each of them come with good spars and wing attach sections?

[bomberfan]

If the spars are that difficult to reproduce, what are the quasi-"new build" B-17s using?
Or did each of them come with good spars and wing attach sections?

The wing attach pieces have been fabricated previously, they're not a major issue. The spar tubes themselves are a nightmare. As far as the "new builds" go, it sounds like Liberty Belle is using the inner wing panels from the aircraft they recovered from Dyke Lake. They'll likely need a new set when it comes time to restore that aircraft. I've heard a couple of stories about what Champaign Lady had done, but from what I gather, they're using the inner wing sections from a wrecked fire bomber, possibly it had good spars? Desert Rat is still in need of a solution, and with the fuselage approaching completion, they'd probably like that to be sooner than later.

[menards]

If the spars are that difficult to reproduce, what are the quasi-"new build" B-17s using?
Or did each of them come with good spars and wing attach sections?

The wing attach pieces have been fabricated previously, they're not a major issue. The spar tubes themselves are a nightmare. As far as the "new builds" go, it sounds like Liberty Belle is using the inner wing panels from the aircraft they recovered from Dyke Lake. They'll likely need a new set when it comes time to restore that aircraft. I've heard a couple of stories about what Champaign Lady had done, but from what I gather, they're using the inner wing sections from a wrecked fire bomber, possibly it had good spars? Desert Rat is still in need of a solution, and with the fuselage approaching completion, they'd probably like that to be sooner than later.

On the spar tubes...One of the facebook groups recently put out a post about the spar tubes. A square tube with rounded corners, The O.D of the tube is a constant 2 and 11/16th inches. The post did not give wall thickness at either end of the tube, but id did say the interior of the tube tapers at a linear rate for approx 1/2 the tube, and then a different linear rate to the end of the tube where the I.D. is the thinnest.

tolerances were +/- 10%

Who would have thought lifes greatest construction mysteries would be the Pyramids and B-17 wing spars.

[bdk]

Who would have thought life's greatest construction mysteries would be the Pyramids and B-17 wing spars.

Too bad Leonard Nimoy isn't around any longer to investigate!

The problem is that the "tribal knowledge" used to make these parts back in the day is gone. Whatever vendor you use will have to reinvent the processes and planning, as well as build new tooling and fixtures. You will also need to find a vendor that is willing to mess around making 5 or 10 sets rather than 100 sets or more that they would do for a commercial or military aircraft program. With only 5 sets or so to be built, it is hard to amortize the trial and error non-recurring costs that would be required to figure this all out.

Another possibility is to redesign the spar caps to be made by alternate methods, perhaps a machined part. This would require some structural analysis and depending on the aircraft certification may require a DER or other FAA approvals.

If this is merely a fatigue concern, there may be an opportunity to put doublers in that area to lower the stresses and limit fatigue accumulation or crack growth rate.

[Cvairwerks]

I found some of the tube data....the external dims are not a problem....2x 2 11/16ths. The internal profile is the big one. I wasn't able to find anything on the internal profile, other than a set of BAC numbers and that they are 4130 with a heat treat to 100Ksi. I would suspect that they were either hot formed in a set of dies, or hot rolled in a closed die and then heat treated afterwards. Today, it's possible that they could be chemical milled and then finished, but that would require some testing.

[menards]

I found some of the tube data....the external dims are not a problem....2x 2 11/16ths. The internal profile is the big one. I wasn't able to find anything on the internal profile, other than a set of BAC numbers and that they are 4130 with a heat treat to 100Ksi. I would suspect that they were either hot formed in a set of dies, or hot rolled in a closed die and then heat treated afterwards. Today, it's possible that they could be chemical milled and then finished, but that would require some testing.

Constant external die and floating moving mandrel that is pulled through the external die for the internal taper. The more I have read about it, its not that they dont know how it was done or how to do it, its just that the tooling would need to be recreated to make the parts. No one has been willing to spend the $ to recreate the dies and manufacture a run of parts. Probably talking big $ for just a small run.