Improper maintenance led to a helicopter crash that killed two Marines from Camp Pendleton earlier this year, according to a new report.

Capt. Adam Satterfield and Major Elizabeth Kealey were killed on January 23, when the UH-1Y Venom helicopter they were piloting crashed just 400 feet from a landing site at a Marine base in Twentynine Palms. And now, a Marine Corps investigation reveals that the crash was caused by improper maintenance that caused the transmission to seize and the main rotor to stop, reports the L.A. Times. The report also revealed that pilot misjudgment was also a factor in the crash.

According to the investigation, a filter cover was improperly installed, causing the transmission to lose oil while the two Marines were flying from Camp Pendleton that day. And while a warming light turned on, the pilots decided not to reroute to a closer airport in Palm Springs or Yucca Valley. Instead, they continued to the Twentynine Palms base, which according to investigators "was directly causal to this mishap."

Major Kealey, 32, was from Indiana, Pa. and was a weapons training instructor and a pilot. Capt. Satterfield, 25, was from Oldham, Ky., and in addition to being a pilot, also supported training operations in the Southern California region. Both pilots were a part of the Marine Light Attack Helicopter Squadron 169.

According to the Times, Maj. Gen. Michael Rocco, who serves as the commanding general of the 3rd Marine Aircraft Wing, approved of the report and its recommendation that there should be no punishment for Marines involved in the vehicle's maintenance.