introduce

They put fuel into the pipe. (Usually "introduce" means to put without force.)

No injection?

It might have been an error. This is what I would expect:

Fuel was injected into the pipe.

I need to ask a question about the grammar of "It might have been an error. This is what I would expect". May I ask? I asked first, because it might not related to the title of the post, but the question occurred to me in here. I guessed I should ask you first.

If it's a logical continuation of the discussion, sure, go ahead.

Thanks.

1)why did you use error, not mistake. (that wasn't grammatical)

2) It was an error, why did you use "might have been".
I would say "It was an error.", because that was clear. It wasn't a probable thing, but it was what happened.

3) This is what I would expect
Again, I didn't understand why did you use "would" in there. I would say: "This is what I expecte

USF1)why did you use error, not mistake. (that wasn't grammatical)

These two words are nearly interchangeable in this situation.

error noun 1. a deviation from accuracy or correctness; a mistake, as in action or speech: His speech contained several factual errors.

To introduce something is to bring upon it, to be new, or the beginning of, or the onset of. So, for "Fuel was introduced into the jet pipe" one way to see this is that "jet pipe" had never experienced any "fuel". Now that the "fuel was introduced into the jet pipe" we can assume that the pipes are no longer free from the fuel and that they have "at least once" had fuel in them.

In other

Thanks, for the reply.

gomblanSo, for "Fuel was introduced into the jet pipe" one way to see this is that "jet pipe" had never experienced any "fuel".

I don't think this is implied at all by "fuel was introduced into the pipe." It just means, as Alphecca Stars said earlier, that fuel was put into the pipe.