Two plural nouns in a row [duplicate]

When I put two plural nouns in a row, should I use plural form for both? Often, when I do so, it seems wrong.

Examples can be:

"components reliabilities" - referring to reliabilities of many different components
"components failures" - failures of components
"systems designers" - designers who creates systems

Another example popped up, as I am writing this question:

"words combinations" - combinations of words

I face this problem, since I am trying to write to cover general cases, without being specific. Also, I know that I could change the word order with 'of' in many cases (e.g. failures of components). But, sometimes, such modification doesn't fit well in a sentence. So, I decided to ask.

Any help would be appreciated.

I would use the singular for the first word in most of your examples:

• "component reliabilities"
• "component failures"
• "word combinations"

but

• "systems designers" This is different because the singular form is (or can be) a "systems designer" -- as a job title of someone who designs many systems, for example. "System designer" may be more appropriate if you're talking about a specific system: "This machine is useless. The system designer must have been an idiot".

You're forming a compound noun from 2 nouns, just not a familar one like "bus stop"

Changing the structure can make things better, it's not exactly a matter of word order though: "Component failures tend to release the magic smoke" is good, but "Components' failures tend to annoy their owners" also works. This last example uses the possesive plural (equivalent to "failures of components") and isn't a compound noun.