Originally Posted by
Water pilot
Boeing Fined $4 Million for knowingly installing faulty parts
There must be more to this story, maybe it was covered elsewhere? Was the plan to certify the planes and fix them before delivery? That would be shockingly lax, but not as shocking as delivering planes with such a major known defect.
By the way, for reference "Muilenburg’s compensation last year was worth $23.4 million, including a $13.1 million bonus and $7.3 million in stock awards. Stock awards from previous years that vested in 2018 pushed Muilenburg’s haul to just over $30 million."
Say what ?? Cadmium and titanium in contact is a major no no - As far back as mid 1960's the embrittlement of titanium parts in contact with cadmium has been well studied and known.
Titanium is embrittled by cadmium from room temperature (solid Cd) up to the 320 C (molten Cd). This includes alloys such as Ti-6Al-4V, Ti-13V-11Cr-3Al, and Ti-8Al-1Mo-1V, not just CP Ti. The Cd must be smeared or pressed into highly stressed Ti surface such that the passive TiO2 film is compromised. References include the following:
"Stress Corrosion Cracking of Titanium Alloys" by R.W. Schutz, pages 265-297 in Stress Corrosion Cracking edited by R.H. Jones (ASM International, 1992)
"Solid Cadmium Embrittlement: Titanium Alloys", p 409 in Corrosion vol 236, no. 10, Oct 1970 by D.N. Fager and W.F. Spurr
"Solid Cadmium Cracking of Titanium Alloys", p 192 in Corrosion vol 20, no. 5, May 1973 by D.A. Meyn
A bit more - During the 2707 ( SST) program at Boeing in the 60's- and as a result of certain testing and information from other aerospace companies and military programs, the embrittlement issue was well known. So much so that all shop tools- wrenches, etc ( which are commonly cad plated ) were verboten. So boeing paid for personal tools to be stripped and nickel plated. Of course the embrittlement problem was worse at expected skin temperatures at supersonic speeds, and or also where moisture is present.
Corrosion Control
Lee H. ErbOriginally published September 1997
(Whether you’re building an SR-71 or a homebuilt with a titanium gear spring, this will be important...)DON’T MIX TITANIUM AND CADMIUM
A cadmium plated bolt installed in a titanium part will eventually result in titanium "embrittlement." Just recently I found out the mechanism for titanium embrittlement: The cadmium, under pressure and/or heat, will flow (infuse) between the grains of titanium. This weakens the grain boundaries and when the titanium is stressed, a crack will initiate.Use passivated stainless steel bolts in the AN and NAS series when bolting a titanium part. Examples are AN4C10 and NAS6304U-10. AN4C10 is a 1/4-inch diameter bolt, 1-5/64 (nominally 1 inch) long, 7/16-inch grip, made of a corrosion resistant steel in the 90 ksi tensile range. NAS6304U-10 is a 1/4-inch diameter bolt, ??? long, 10/16 grip, made of A286 corrosion resistant steel and unplated.
Note: The NAS63xx series is A286 cres (cres--corrosion resistant steel, i.e. stainless steel) in the 160 ksi tensile range. The NAS62xx series is alloy steel and the NAS64xx series is 6AL-4V titanium in 160 ksi tensile range at normal temperatures. At 450 deg F it is good for 95 ksi. (Bolt selection is another long subject.)
Even the preparers of the NAS specifications had to learn about titanium embrittlement. When the spec was initially prepared in 1968 there was a cadmium plated titanium bolt defined. The galvanic table indicates that it would act sacrifically as on a steel bolt. It was declared "Inactive for New Design" after December 1991.
Thanks again to Steve Mitchell and Ron Yarborough for sharing their knowledge.
https://corrosionjournal.org/doi/abs...9312-26.10.409
So what magic system is Boeing using to prevent such embrittlement ??
