Democratic lawmakers from Massachusetts sent a letter to Defense Secretary Lloyd Austin this week requesting he ground the controversial Osprey aircraft, sharing concerns after a recent investigation found serious incidents involving the hybrid aircraft have spiked in recent years.

The Monday letter from Sens. Elizabeth Warren (D) and Ed Markey (D), along with Rep. Richard Neal (D), pointed to the "spike in grave safety issues over the past few years that include the need to address mechanical issues at the center of many of the aircraft’s past crashes."

"Given the current concerns about the safety of the V-22, the aircraft should be grounded, and should not be deployed again until the platform’s significant deficiencies are fully addressed," the lawmakers wrote, demanding answers to several questions about the safety of the Osprey.

The Osprey is one of the U.S. military's most controversial aircraft. The V-22 is valued because it takes off and lands like a helicopter and flies like a plane, making it a hybrid aircraft that can maneuver into challenging areas.

© The Hill