SALT LAKE CITY (AP) — Mechanical failure forced an air tanker to make a crash-landing in northern Nevada over the weekend, the National Transportation Safety Board said Tuesday.

The bay doors for the plane’s left-side landing gear failed to open as the aircraft approached the runway at the Minden-Tahoe Airport, NTSB investigator Kurt Anderson said.

Officials are trying to determine the cause of the jammed doors.

“The gear tried to extend, but the doors wouldn’t let it,” Anderson told The Associated Press.

The pilots knew their left-side landing gear wasn’t deploying and circled the airport trying to fix the problem. They were eventually forced to land.

A videotape shows the plane dropping to its belly and sliding across a runway. No one was hurt.

The Lockheed P2V was fighting a wildfire south of Reno on Sunday, the same day another firefighting plane of the same vintage went down in southern Utah, killing two pilots.

Once a Cold War-era submarine attack plane, the Lockheed P2V has for years been both a mainstay of the nation’s aerial firefighting arsenal and a cause for concern.

Flying in the turbulent, unforgiving skies above raging wildfires, the planes have crashed at least seven times from either mechanical problems or pilot error, causing 16 deaths, dating back to 1990 when they were slowly added to the nation’s firefighting fleet.

The plane’s fuselage is fitted with a tank for flame retardant.

The Lockheed P2V has both a jet engine and propeller under each wing. The jet engines provide added lift, which is useful for flying low over wildfires to drop retardant, Anderson said.

The Federal Aviation Administration and Forest Service will determine if the plane can be put back in service after repairs, he said.

Aside from dents and a bent propeller, Anderson said the plane was structurally intact.

The damage was so slight Anderson said he wasn’t certain the hard landing qualified as an accident.

“We have found no damage to the left wing or the primary structure of the aircraft,” he said.