NASA ripe for Poka Yoke?

[Wes Bucey]

Do you think NASA might be ripe for Poka Yoke?

Shuttle Gears Were Installed Backward
Mon Mar 22, 9:34 PM ET
By MARCIA DUNN, AP Aerospace Writer
CAPE CANAVERAL, Fla. - To prevent another catastrophe, NASA (news - web sites) will replace braking mechanisms on all its space shuttles after discovering some of the gears were installed backward.

Shuttle program manager Bill Parsons said Monday he has launched an investigation into why the rudder speed brake gears — all old original parts in the shuttle tails — were never inspected in more than two decades of flight. If one of the improperly installed gears had been in a high-stress position, it probably would have led to the destruction of the spacecraft at touchdown, he said.

"Bottom line is, it was not good," Parsons said.

The rudder speed brake is used to guide and slow the shuttle as it comes in for a landing. If even one of the four sets of gears that operate the mechanism jams, then the spacecraft could not land safely.

As it turns out, the reversed gears found recently in Discovery were in the least stress-prone position and never failed. But one of the replacement gears — a spare set that was also installed backward — would have ended up in a much more high-stress location in the tail.

All the rudder speed brake gears in NASA's inventory — dating as far back as the 1970s — are being X-rayed to see whether they were properly built, and to look for rust and microcracks, already spotted on some gears.

Parsons said new or refurbished gears should be installed in time for shuttle flights to resume next March, after a two-year grounding following the Columbia tragedy. The extra work may put NASA a week or two behind, but "I think we'll be able to make that up," he said.

Discovery will fly first because the work is further along. Atlantis must be ready to quickly go to the Discovery crew's rescue at the international space station, however, if need be during an emergency.

The installation problem surfaced late last year and prompted NASA to delay the next shuttle flight from fall 2004 to spring 2005.

"Because of the way these gears go together, you can actually make a mistake and put them in incorrectly, and there was not a good process back in the timeframe" to catch mistakes, Parsons said.

He said the maker of the rudder speed brake mechanisms, Hamilton Sundstrand in Rockford, Ill., now has better quality control.

At the same time, NASA is inspecting the plumbing in each of its three remaining shuttles. The hoses in question are also original shuttle parts and some are starting to leak, Parsons said.

"As we deal with aging vehicle kind of issues, we will find other things along these lines as well, I'm sure," he said.

Parsons said engineers are making good progress on the inspection booms and wing-repair kits that will be required on all future shuttle flights.

Columbia was destroyed and its seven astronauts were killed during re-entry last year because of a hole in the left wing caused by a piece of insulating foam that broke free at liftoff.

[Claes Gefvenberg]

Originally Posted by Wes Bucey

Do you think NASA might be ripe for Poka Yoke?

CAPE CANAVERAL, Fla. - To prevent another catastrophe, NASA (news - web sites) will replace braking mechanisms on all its space shuttles after discovering some of the gears were installed backward.

Ouch! Yes, Poka Yoke sounds like a good idea. In fact, I think we can all use the text above as food for thought. Most of us could probably find similar mishaps in our own companies. I know I can...

/Claes

[The Taz!]

My question is why wasn't it picked up on the original inspections. . . never mind the subsequent ones. . . do they use Control PLans?? Aerospace developed FMEA's . . . did they address it?? Will they update it?

Agree totally that a Poka Yoke in the design is needed.

[Randy]

Chuck Yeager found an installation flaw in an aileron assembly of the F86. Mechanics could (and did) install a bolt contrary to design requirements that would (and did) cause the controls to freeze when inverted (Yeager was able to take corrective action).

We found things on the Blackhawk, Apache and other aircraft that could be done likewise.

Murphy lives, and designers can't beat him...there is always a bigger hammer!!

[The Taz!]

Originally Posted by Randy

Murphy lives, and designers can't beat him...there is always a bigger hammer!!

Randy. . .

This is why God created Quality Professionals! . . . massochistic as we are. . .

[Randy]

I've seen "Q professionals" sign off on insignificant items like tail rotors blades installed backwards, mis-matched hardware, krappy welds, horribly erroded compressor blades, mis-installed servo's, and numerous other trivial things related to aviation maintenance. A majority of the time the "Q professional" had no hands on experience to apply to the "Q" requirement...neither do most engineers. The problem I see is a growing lack of relevent and personal technical expertise of the people involved with systems design and inspection.. Lot's of theory, but no practical application of the theory to fall back on on their part.

Besides...shuttle flights are all validation flights anyway. The last one proved that there was a design and systems flaw as validation tests are supposed to.

[Claes Gefvenberg]

Originally Posted by Randy

The problem I see is a growing lack of relevent and personal technical expertise of the people involved with systems design and inspection.. Lot's of theory, but no practical application of the theory to fall back on on their part.

Yes. Hands on experience is priceless. On the other hand, the opposite extreme can be just as devastating: People with lots of hands on experience but lacking the theoretical insight can cause havoc just as easily...

Originally Posted by Randy

Besides...shuttle flights are all validation flights anyway. The last one proved that there was a design and systems flaw as validation tests are supposed to.

Considering how complicated that contraption is, that has to be absolutley correct. We can not and should not expect any venture into space to be particularly safe for many years to come, if ever... We must remember that it takes a failure in but one of all those systems to cause disaster. With that in mind, I think the shuttle is a great success in spite of the two accidents.

/Claes

[The Taz!]

Originally Posted by Randy

The problem I see is a growing lack of relevent and personal technical expertise of the people involved with systems design and inspection.. Lot's of theory, but no practical application of the theory to fall back on on their part.

I can't agree with you more . . . I remember when I first started to work as a platform QE at a company making fuel delivery systems. . . the ME took me by the hand and made me assemble a bunch of them. . .

I also remember a company that took all new design engineers and put them in inspection for a few weeks. . . they found how not to design things. . .

There needs to be a balance. . .

yes. . . I have to admit I have a new respect for the shuttle Crews. . as one astronaut commented, "he's sitting on top of 40,000 parts made by the cheapest supplier" Don't remember which one. . . Oh well. . .