The National Transportation Safety Board blames the pilot and a ground crewman for the crash landing of a small helicopter at Tulsa International Airport in February.
Osage SkyNews 6 pilot Will Kavanagh spotted the damaged Robinson R-44 helicopter from the air on February 6, 2013.
He could tell the chopper was missing its tail rotor and could see that the aircraft had spun around several times on the ground.
In the NTSB's Probable Cause Report on the incident, it blames the accident on the "line technician's failure to remove the refueling mat from the helicopter fuselage following service, which resulted in the mat striking the tail rotor, and the pilot's inadequate preflight inspection."
The refueling mat is a roughly two-foot by one-foot rubber mat which is placed around the fuel filler tube to prevent damage to the helicopter's paint by the fuel nozzle.
In his Factual Report released in September, NTSB investigator Michael Folkerts wrote that the pilot was leaving TIA at about 5 p.m. to fly down to Jones Riverside. When the helicopter reached about 150 feet in altitude, the mat struck the tail rotor and knocked it off.
The pilot told the NTSB he felt the helicopter buck and start to turn to the right, so he immediately cut fuel to the engine and began an autorotation, a maneuver helicopter pilots use to land if they lose engine power or the tail rotor.
The pilot, who is rated as a commercial helicopter and instructor pilot with 1,255 hours of total flight time, landed safely and no one was hurt.
Witnesses found the mat and the tail rotor blades nearby.
Photos provided by the NTSB show the mat was almost ripped into two pieces.
The helicopter, which is owned by Crumpton Aviation, sustained some damage in the landing.