The right main landing gear collapsed on impact when a Delta flight landed at Toronto’s Pearson International Airport last month, with the wing hitting the runway and fuel spray causing a massive fire, according to a preliminary report from the Transportation Safety Board of Canada.

There was no final cause of the crash in the report released Thursday, but the investigation found that the right main landing gear broke and collapsed on impact as the plane landed at a high descent rate.

The first officer, who was in her fifth straight day of flying, was at the controls of the plane, according to the report. She had 1,422 hours of flying total, which is below the Federal Aviation Administration minimum to be a commercial pilot.

She was able to fly commercially with a special exception from the FAA because she had a specific aviation degree and received a waiver, the report said.

All 80 people on board survived though 21 passengers were injured — two seriously, the report said.

Delta said in a statement, “For everyone at Endeavor Air and Delta, nothing is more important than the safety of our customers and our people. That’s why we remain fully engaged as participants in the investigation led by the Transportation Safety Board of Canada. Out of respect for the integrity of this work that will continue through their final report, Endeavor Air and Delta will refrain from comment.”

What happened right before the plane landed?

About 13 seconds before landing, the plane’s airspeed increased to 154 knots, “consistent with a performance-increasing wind gust,” according to the report. The first officer, who was flying the plane, pulled back the thrust levers to decrease engine thrust.

Then, 2.6 seconds before touchdown, the Enhanced Ground Proximity Warning System alert “sink rate” went off, indicating a high rate of descent, according to the report.

Less than one second before touchdown, the aircraft’s indicated airspeed was 134 knots and its groundspeed was 11 knots, per the report. The bank angle was 7.1 degrees to the right, and the pitch attitude was 1 degree nose up. The rate of descent was recorded as 1,110 feet per minute, according to the report.

What happened during touchdown?

The side stay attached to the aircraft’s right main landing gear fractured on landing, according to the report, while the landing gear retracted.

The wing root fractured between landing gear and fuselage, causing the right wing to release a “cloud of jet fuel” when it detached from the fuselage, according to the report, which then caught fire when the aircraft was sliding on the runway.

The report also revealed the cockpit door was jammed shut and the flight crew exited the plane through the emergency hatch on the ceiling of the cockpit.

After all 80 people on board evacuated, emergency personnel entered the fuselage and an explosion occurred outside the aircraft at the left wing root, according to the report, though the cause has not yet been determined for the explosion.

No obvious preexisting malfunctions were found on the components of the flight control, the report said.

Preliminary information from the flight data recorder did not have any “caution or warning messages” about the flight controls.

While the first officer had flown for five straight days, including the same day on a flight from Cleveland at 8:19 a.m., the captain had not flown for seven days. The captain has worked for Endeavor since October 2007. He has 3,570 hours total flight time and 765 hours on the CRJ-900.