C-130 fleet inspections ordered

The USAF issued a time sensitive technical order March 10th affecting all models of all C-130s in the inventory. A C-130H undergoing routine maintenance at Werner Robbins was found to have cracks in 5 of 13 upper wing barrel nuts. The outer wing attaches to the center wing with 13 bolts and barrel nuts on the top, and 15 on the bottom. All of the bottom barrel nuts were found to be fine, but the upper barrel nuts had cracks.

As of the 14th, 40% of the aircraft had been returned to service, with 2/3rds of the 600 aircraft inspected. Priority is on special operations, aeromedical, and forward deployed aircraft.

The cause of he cracks appears to be caused by hydrogen embrittlement. When exposed to hydrogen, metals such as high strength steel become brittle and crack.

WOW that is pretty spooky!!!!
Just imagine landing the thing and then finding out an hour later
that your C130 had these cracked nuts on it. I would personally be heading for the bar after that kind of news, lol.

Oh boy. I just hope our Air Force isnt going to devolve into flying these planes with just spit and chickenwire holding them together.

and I very much doubt Obama is going to spend any money on modernizing the AF and fixing our worn out fleet.

These planes go through a process called NDI which is a sort of x-ray of the planes structure every year. If they find a large number of problems in any one certain area, they will pull all in for inspection as standard ops. The C-130 is a beast of a plane. If you are the crew chief and your plane has cracks, you will have a less than enjoyable few months.

I have over 5000 hours on C-130 E/H1/H2/H3. They are going to modernize the H series and retire the older E series. This could be delayed with the Joint transport coming on line. This aircraft is about 1/2 of a C-130 but they will build many and spread them across all the services. So though it is 1/2 the cargo capabilities it will have shorter landing/takeoff distances that makes it useable in more tactical situations.

Yeah, we worry about hydrogen embrittlement in a lot of navy components too. But the thing about xrays, is it wont pick up unbonding due to the lack of a difference in shielding capability. so there could be a lot of molecular unbonding, and we'd never know. Do you know if they also do ultrasonic tests on the aircraft?

We got to watch them doing a test on our C-135s where they had to go rivet by rivet with a probe. They would circle the outside of the rivet, trying not to touch where the skin indents, while watching an o-scope. They couldn't watch where the rivet was, because they had to watch the screen for a jump in voltage. Any jump meant a crack. He had to do the entire wing on both aircraft. He let us try a couple, and we couldn't do it, even looking at the rivet area we were screening.

reply to post by Zaphod58


Its Warner Robins. The mechanics told supervisors about this problem for YEARS. Finally they listened and had to down all the planes at once. They could have spent the extra man hours and fixed the problem when they were in the depot station to begin with but never did and sent them out bad. Way to go US military!

I don't blame the depot guys at all. They're under a lot of pressure to keep the planes flying and get their inspections done as fast as possible, and get them back in service. There are other checks that are done at the unit level that could have caught them too. Unit level phase inspections go deep enough into the wing that they probably could have caught them there. Our -135 phase at the unit level tore deep into them.

I don't blame the depot guys either. I think the supervisors and the generals who have no idea how to fix a plane are in their offices making paper look good. The poor mechanics have to do what they say so, if a superior says let it fly, then it flies. Even though the mechanics, the ones fixing the problem tell them look, this is bad, we need to order parts for it, its going to take extra time for parts and labor, they don't care, paperwork says what we needed to fix is fixed so let it fly.
Thats what I am saying, this problem has been around for YEARS but no one listened to the mechanics, they let them fly cracked bolts and all.

reply to post by concerned190


We used to fly C-135s with problems that should have been fixed, but weren't right away. One of our birds had a pretty significant bit of post hangar fire skin damage, we flew it for 6 months or so before it went to PDM. We changed out the lights that melted, but that was about it.

When the problems aren't fixed, rest assured its not the mechanics fault, they tell the superiors but its up to the superiors to say yay or nay to get problems fixed.

reply to post by concerned190


Sometimes it's a matter of it either not having the budget, or it's not a problem that's going to cause a major issue yet. We used to fly our birds with corrosion in them because it was a matter of it being too expensive to fix at the time. As long as it wasn't something major that was an immediate SOF issue, then we'd fly it. One or two barrel nuts being cracked isn't a SOF issue yet.

Ok, I gotcha......I guess I thought it was a bigger deal than it was.
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