Foam Gluing Flaw Killed Columbia Astronauts

Freshly Exhumed writes "Now it can be told: NASA's Columbia Accident Investigation Board has blamed the faulty application of insulating foam for the loss of the Columbia orbiter. From the chief engineer for the external tanks project: '...NASA concluded after extensive testing that the process of applying some sections of foam by hand with spray guns was at fault.' And further: 'It was not the fault of the guys on the floor; they were just doing the process we gave them'."

Comments

There is no GLUE!

[teridon]

Nor are there any tiles, as more than two fool implies.

The foam is sprayed on, and it adheres directly to the External Tank's aluminum substrate (and itself, of course). Some metallic sections of the tank are coated with epoxy before being sprayed. But the process is slightly different on the bipod structure:

The insulated region where the bipod struts attach to the External Tank is structurally, geometrically, and materially complex. Because of concerns that foam applied over the fittings would not provide enough protection from the high heating of exposed surfaces during ascent, the bipod fittings are coated with ablators. BX-250 foam is sprayed by hand over the fittings (and ablator materials), allowed to dry, and manually shaved into a ramp shape. The foam is visually inspected at the Michoud Assembly Facility and also at the Kennedy Space Center, but no other non-destructive evaluation is performed.
-- excerpt from CAIB report vol. 1, p. 51

You can get all the CAIB reports here.