For those who aren't on the recent 3.2 build, Petah's Crate chances will look like this:

Tier 1: 63% chance uncommon fusion, 37% chance for rare fusion
Tier 2 -5: 63% chance uncommon fusion, 31% chance for rare, 6% chance for epic

Loyalty:
5 spins for Tier 1
14 spins for Tier 2
14 spins for Tier 3
14 Spins for Tier 4
14 Spins for Tier 5

Each crate contains 3 items.

This crate can only be bought a maximum of 15 times per day.

The crate was fixed in 3.2 to give players a fairer opportunity to gain parts. If you are on 3.2 please refer to the following FAQ (LINK)

Apologies for any confusion and inconvenience this may have caused.