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<a href="news_article2829.html">Boeing sues Alcoa over faulty F-22 fighter jet parts</a>

I can't believe this. The F-22 already has defective parts installed in it?!? Now the solution is to inspect it more? So if we are saving money by just inspecting it instead of replacing are we placing people's lives under cost concerns? Remember it took over 20 or 30 years (eagle guys help me with this one) to "find" defective beams in the F-15 . At $120 million each you'd think they'd be more careful with their inspections of parts before installation on the final assembly of the aircraft.

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I wonder what it is exactly. If it has to do with chemical make-up, I'm pretty sure Boeing doesnt inspect parts to that extent. They expect their suppliers to deliver what they promise.

I used to deal with Alcoa parts. Mainly procurred spring washers, panel fasteners and other parts for sale to Indy car teams mostly, some overseas Formula 1 racing teams too. The components were small stuff, but very expensive. Maybe problems related to those types, but Alcoa also deals with lots of different parts and goodies.

So does this mean that the first 100 aircraft have a limited max G or just that they can Max G but they have to be inspected after every max G and taken out of flight line if deficiencies show??

And I hope the remaining 80 aircraft won't have this failure??

Perhaps USAF will use this news for a future request for additional 100 tranche2 Raptors. I'd support that.

Elite 1K Joined: Jul 22, 2005 Posts: 1088 Status: Offline

geogen wrote:

So does this mean that the first 100 aircraft have a limited max G or just that they can Max G but they have to be inspected after every max G and taken out of flight line if deficiencies show??

And I hope the remaining 80 aircraft won't have this failure??

Perhaps USAF will use this news for a future request for additional 100 tranche2 Raptors. I'd support that.

A more likely scenerio would be brain trusts like Ricionni, POGO, and the liberal left using it to crow about the F-22 being a defective lemon.

So does that mean that this problem will not be fixed, not only will not be fixed now but "ever"?

The parts in question (titanium) were not heat treated correctly, reducing the resistance to crack growth. That means they have all the strength needed for full limit maneuvers, but if cracks start to appear they will grow faster than desired. More frequent inspections will detect the presence of cracks sooner and will allow better tracking of crack growth. If crack length reaches certain limits, the parts are either repaired or replaced.

About 700 of these parts were made by Alcoa and approximately 10% were incorrectly heat treated.

Crack growth tracking is planned into every airplanes service life, so this is not a big deal. Cracks can grow faster than desired for a number of reasons, including using the airplanes harder than expected, degraded material properties, and metal cutting errors during manufacture. That is why there are extra margins designed into the structure. Every airplane has problems like this.

John,

Am I incorrect that the first 100 or so F-22s had stated components which were incorrectly manufactured? That is the point in focus I think. And it is a problem since of course these birds 'should' be training and operating 'as hard as expected' testing out the maximum envelopes, etc. To retrofit these components is surely going to take dozens of aircraft out of operation, for months at a time at $100s of millions if not $billions of dollars additional cost.

This is a major issue given that there is only 1 single tranche F-22 production program planned as of now, whereas if a more normal, multi-hundred unit program existed, (such as with initial F-16 issues), they could simply upgrade the follow-on batch. In such as case, the said 'problem' would not be unnatural and hence addressed in the next block.

In the current Raptor case they couldn't afford to screw up at all, given the significantly reduced numbers and single block program. Hence, my support for an additional 100 plus/minus Raptor tranche II line. (To be determined by next admin?)

Taking advantage of the supplemental purchase, the USAF could update with improved avionics, computing, radar and passive sensors further advancing the capabilities, survivability and deterrence value.

Geogen, I am not an insider on the F-22 program, but I speak from 40 years experience as a structural engineer for General Dynamics and Lockheed Martin. Everything I say about the F-22 problem is based on what I have read from many sources. First, discount everything you read in newspapers, they rarely ever get anything right.

As I said about 10% of the parts were incorrectly heat treated. I don't know how the parts were distributed on the "first 100" F-22s. So the problem is not near as wide spread as you may think. I wonder where you get the idea it will cost "100s of millions if not billions" to retrofit these relatively few airplanes, especially when it may not be necessary to retrofit them at all. Again, as I said, the problem is not one of reduced strength, but one of a POTENTIAL for reduced service life over many years.

The idea of spending billions on an additional 100 airplanes just to solve this problem is ludicrous. If we need another 100 airplanes, get them at whatever they cost of course. Did you see what Boeing is suing Alcoa for? A whole 12 million bucks, with a lot of that being legal fees for the lawyers.

I also think you may misunderstand in comparing 4000+ F-16s with 183 F-22. I assure you, any problems found in early F-16s were addressed in later airplanes, but we certainly did not let the early airplanes fly unsafely. They were repaired as needed, just the same as the F-22s will be.

Here is my guess as to what will happen. The normal fleet management program will track usage of every F-22, comparing actual usage with design usage. A new durability analysis will be performed on the discrepant parts using design usage and actual usage. New lifetime predictions will be made to determine if shorter inspection intervals will be required. The actual usage will be updated every 500 hours of flight time and the life analysis repeated. Inspection intervals will be adjusted as necessary. If cracks are eventually found, their growth will be closely monitored. If growth indicates reduced life, the parts will be repaired or replaced at one half the flight hours predicted for failure.

If they want to be extra conservative, they could manufacture some similarly discrepant parts and test them in the structural lab to determine their life under design usage conditions, to provide a baseline comparison with good parts.

This is a routine problem, believe me. Airplanes usage is never exactly the same as design. Structural parts never have the same strength or durability they are designed for. The load on the structure is never exactly the same as design. We accept these problems and solve them with factors of safety and two-lifetime usage.

I have used the the term "usage" several times, so I'd best explain it. For every combination of possible gross weight, fuel load, weapon load, altitude, airspeed, mission type, mission segment, maneuver type, and maneuver severity, there is a different load and stress on every part of the airplane. There are millions of possible combinations, so this whole spectrum of data is edited down to a reasonable number of conditions. That is called the design usage. The structure is analyzed for crack growth assuming cracks pre-exist in all critical structural parts , and a complete airframe is lab tested to two lifetimes of that usage. When the airplanes go into service the actual usage of every airplane is tracked and compared to design usage. Inspection intervals are adjusted according to the severity of the actual usage compared to the design usage.

Finding this problem at this stage of the F-22 service life proves that the system works. Look at the F-15 discrepant cockpit longeron, 36 years after the first flight. The USAF should be very pleased the F-22 problem was found so soon. Modern fighters are the most complex machines ever built. To have so few problems, our 4th and 5th generation airplanes are remarkable.

Once again, don't try to make a mountain out of a molehill.

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Boeing sues Alcoa over faulty F-22 fighter jet parts