O azar é que o elevador parou quando eu estava saindo.

Yes, it’s natural. O azar é que... means something like The unfortunate thing is that..., The bad luck is that..., or more idiomatically The problem is that... in this context.

So:

O azar é que o elevador parou...
= The unfortunate thing is that the elevator stopped...

It sounds a bit more conversational and expressive than a plain factual sentence.

In Portuguese, abstract nouns often take an article when used in a general or specific statement.

So o azar here is not just bad luck in the abstract, but more like the bad luck / the unfortunate part of the situation.

Compare:

• Azar! = Tough luck! / Bad luck!
• O azar é que... = The problem / unfortunate thing is that...

Using o makes the phrase sound complete and idiomatic in this sentence.

Here, é que is simply part of the structure X é que..., which means the thing is that... or what happens is that...

So:

• O azar é que o elevador parou.
• literally: The bad luck is that the elevator stopped.

This is not the same as the emphatic é que you may see in other sentences. In this case, it is just the normal linking verb é + que introducing the explanation.

Parou is the preterite form of parar, and it shows a completed event:

• o elevador parou = the elevator stopped

This fits because the stopping is seen as a single event that happened at a particular moment.

If you said parava, it would suggest something habitual, repeated, or backgrounded, which does not fit as well here.

So the sentence contrasts:

• parou = the main event, completed
• estava saindo = the ongoing action in progress when it happened

Estava saindo means was leaving or was in the process of getting out. It describes an action that was ongoing when another event happened.

So:

• quando eu estava saindo = when I was leaving / as I was getting out
• quando eu saí = when I left

The first version focuses on the action in progress. The second sounds more finished and punctual.

In this sentence, Portuguese uses estava + gerund because the speaker wants to show that the elevator stopped during the act of leaving.

Saindo is the gerund of sair, which means to leave, to go out, or to get out.

In this sentence, it most likely means:

• getting out
• leaving

Because the sentence mentions an elevator, the most natural interpretation is probably I was getting out of the elevator.

Portuguese does not explicitly say do elevador here, because it is understood from context. If you wanted to make it clearer, you could say:

• O azar é que o elevador parou quando eu estava saindo dele.
• ...quando eu estava saindo do elevador.

Yes. Portuguese often drops subject pronouns when the verb already makes the subject clear.

So both are possible:

• quando eu estava saindo
• quando estava saindo

Both mean the same thing here.

Including eu can add a little emphasis or clarity, but it is not required.

This is an important tense difference.

quando eu estava saindo

• when I was leaving
• ongoing action
• background action interrupted by another event

quando eu saí

• when I left
• completed action
• sounds more like a finished point in time

So:

• O elevador parou quando eu estava saindo. = The elevator stopped while I was in the middle of getting out.

• O elevador parou quando eu saí. = The elevator stopped when I left.
  This sounds less natural if the idea is that it stopped during the action of exiting.

Grammatically, saindo by itself just means leaving / going out. The sentence does not explicitly say from the elevator.

However, because o elevador is the thing that stopped, the most natural reading is:

• the elevator stopped while I was getting out of it

If the speaker wanted to remove all doubt, they could say:

• ...quando eu estava saindo do elevador.

So the original sentence relies on context.

Yes. Portuguese is flexible here.

For example:

• O azar é que o elevador parou quando eu estava saindo.
• Quando eu estava saindo, o elevador parou.
• O elevador parou quando eu estava saindo.

All are grammatical.

The original version puts focus first on the unfortunate part of the story. If you move the time clause to the front, you emphasize the timing more.

They are close, but not always identical in tone.

• azar often means bad luck, misfortune, or even tough luck
• má sorte is a more literal bad luck

In this sentence, O azar é que... sounds idiomatic and natural.
You could say A má sorte é que..., but it is less common and sounds less natural here.

A more natural alternative could be:

• O problema é que o elevador parou...
• O ruim é que o elevador parou...

But O azar é que... works well if the speaker is framing it as an unlucky situation.