Learn Finnish: Matkustajan täytyi löytää hätäuloskäynti, ennen kuin hätätilanne alkoi. - The passenger had to find the emergency exit before the emergency started.

In Finnish, ennen kuin (before) introduces a subordinate clause. You must put a comma before it when it separates a main clause from a subordinate clause, which is different from English where we rarely put a comma before the word 'before'.

Does ennen kuin change the word order of the clause that follows it?

No, a clause starting with ennen kuin uses standard word order (subject + verb + object or complement). In this sentence, the subject hätätilanne comes normally right before the verb alkoi.

Why is matkustajan in the genitive case (ending in -n) instead of the basic form matkustaja?

This is required by the necessity verb täytyi (had to). In Finnish, the person who has to do something is put in the genitive case. You can think of it literally as 'It was of the passenger's necessity to find...'.

Normally an object gets an -n ending. Why is hätäuloskäynti in its basic dictionary form here?

When the main verb is a necessity verb like täytyy or täytyi, the total object does not take the usual -n ending. Since the person doing the action (matkustajan) already has an -n ending, the object hätäuloskäynti stays in its basic nominative form.

How are the words hätäuloskäynti and constructed?