Multiple KC-135s found with keel beam corrosion

A KC-135 being prepared to fly back to its unit after PDM was found with about 1.5 inches of corrosion on the keel beam. After word was put out to inspect the beam on all aircraft, an additional 14 were found with corrosion.

Initially it was thought that it would take a year to complete the repairs, but with some creative thinking that was reduced to six months. An example of that was that the material needed that was the correct thickness would take 12 weeks to arrive. One of the machine shops was able to order a thicker material that arrived in two weeks, and machined it down to the correct size.

TINKER AIR FORCE BASE, OKLAHOMA -- The recent discovery and repair of corrosion on a structurally-crucial part in 15 KC-135 Stratotankers, accomplished jointly by several units at Tinker Air Force Base, has increased the safety of the fleet and gained recognition by high-ranking Air Force officials.

In April, an aircraft was being prepared for return to its unit following programmed depot maintenance, when a mechanic in the 76th Aircraft Maintenance Group was in the wheel well — a space the size of a small closet — and noticed about 1.5 inches of corrosion on the keel beam.

Mostly hidden by other structural components, the keel beam runs along 5 to 6 feet of the body of the KC-135, supporting the floor of the aircraft.

www.tinker.af.mil...

That is a cool story of proactive ingenuity. The article stated that the beam was made of standard Aircraft aluminum. Most likely a galvanic corrosion from being attached to another metal, like stainless steel in a humid environment. Good on them, and probably saved some lives by discovering it.

a reply to: charlyv

A combination of galvanic corrosion and electrolytic corrosion was the reason the WTC towers had to be demolished. The corrosion was noticed before the towers were finished.

. . . a mechanic . . .

Good man.

See it, say it, sorted.

#1 its cool that the crews can think out of the box. Kudos to the PDM Team.

#2 Its cool that the brass allowed that sort of creative thinking

Number 1 rule of corrosion.What you see is only a third of what corrosion is actually there.Stainless Steel plus Aluminium is the worst offender for galvanic corrosion.
LOL I like this line.

“Some of these (aircraft parts) are not made to be removed … This was one of those cases.”

Give me a drill,a hammer and a set of pin punches

a reply to: Blackfinger
When the SRM says you have reached a limit and an EA or EI says keep digging, you keep digging. Doesn't matter if it goes out of limits, that's what tech services is for, and the manufacturers people to work out. Happy days with a die grinder till the powders gone!

I did an old aircraft tailplane rib once,came out clean as a whistle after bead blasting.Put it through a mild acid bath and the middle of it turned black from inter granular corrosion.