Investigators probing the June 3 crash of Dana Air Flight 992 report that the aircraft’s flight data recorder (FDR) was destroyed in the post-crash fire, leaving them without key information to help determine why the MD-83 apparently lost power in both engines on approach to Lagos Muhammed Murtala Airport.

“The digital tape-based memory in the FDR succumbed to the post-crash fire and melted, consequently no data could be recovered,” Nigeria’s Accident Investigation Bureau (AIB) said in an interim report.

The aircraft’s cockpit voice recorder (CVR) captured 31 min. of audio, the interim report reveals. The flight crew discussed a “non-normal condition” concerning the “correlation” between the throttle setting and engine power indication/engine pressure ratio as the plane cruised toward the airport, investigators found.

At that point, the crew was not concerned that the problem would “affect the continuation of the flight,” the report said.

Just seven minutes later, however, as the plane began its initial descent, the crew became “increasingly concerned” about the engine readings, investigators determined. The crew continued the approach, deploying slats, extending flaps, and dropping the landing gear. At 15:42 local time—or about 27 min. into the CVR recording—the crew declared an emergency, citing a “dual engine failure . . . negative response from throttle.” About a minute later, the captain told the first officer that they had “lost both engines.”

“During the next 25 seconds until the end of the CVR recording, the flight crew was attempting to restart the engines,” AIB reported.

The airplane crashed in a residential area about 5.8 miles north of the airport, “approximately” on the extended centerline of Runway 18R. All 153 people on the aircraft were killed, as were 10 on the ground.

Investigators said that preliminary readings from fuel samples taken from the truck that serviced the aircraft and the refueling tanks at Abuja, where the flight originated, found no contaminants.