When the question of aft cabin noise was being discussed at a Board Level meeting at Lockheed, Lloyd Frisbee, one of the VP's got some clay and a model of the L-1011, and slapped a fairing below the lip of the S-duct inlet to the top of the cabin.
" Do something like that", he said.
Aero took the model and SCALED the finger shaped clay, and we built it to their drawing! And flew it. And it actually worked!
The first part made was intended as mock-up only, as assembled on the #1 Tristar. We had sent some of the mechanics to Scaled Composites to learn how to work in foam for the job. Not intended for flight, nor stressed at all properly.
We flew it anyway.
Lost a BIG chunk out of it the evening before the Tristar was due in Burbank for a company open house. Lots of scrambling around patching the hole in the fairing that swing shift...
2 weeks later, an inspector in a cherry picker happened to look down at the horizontal, and noticed a giant gash about 15 feet out from the fuselage on the same side the piece had come off the fairing. The thing would have had to fly directly out from its location to hit the stabilizer there. A few layers of fiberglass tore right thru the thick skin of the horizontal.
And then we took it off. The acousta-nuts who had measured aft-cabin noise came back to get another "baseline" inflight data..
They're walking around in the aft cabin with their Nagra recorders checking this and that...
Up forward over the wing in the data center, we hear this whistling noise... but back there in the aft cabin, which had zero insulation, you couldn't!
Walked back, looked up.. and THRU the skin, where all the rivets holding the bottom of the fairing had been, but yet to be replaced!
No wonder it whistled!