The deadly Fire Ball accident at the Ohio State Fair last month was caused by “excessive corrosion,” says the ride maker.

An investigation conducted by the Dutch manufacturer of the pendulum-type thrill ride — which swings riders 40 feet in the air and spins them — has found that the thickness of its gondola support beam’s wall had been “dangerously reduced” over the years due to rust.

“This finally led to the catastrophic failure of the ride during operation,” Albert Kroon, product manager for KMG International BV, said in a statement Sunday.

The “excessive corrosion” was discovered inside the Fire Ball’s gondola support beam during a “metallurgical inspection” of the ride, Kroon said.

It ultimately caused the metal arm of the ride to be weakened to the point of breaking off — which is exactly what happened July 26 at the Ohio State Fair, when one of its passenger gondolas detached from the supporting sweep arm and went flying into the air. The malfunction left one person dead and seven others, ages 14 to 42, injured.

“KMG has reviewed the results of the inspection and worked with industry safety experts to develop an inspection protocol in the form of a Safety Bulletin to allow properly inspected and maintained rides to safely reopen,” Kroon said.

The company had ordered fair and carnival operators throughout the country to stop using the Fire Ball ride and others like it following the accident at the Ohio State Fair.

The family of 18-year-old Tyler Jarrell, who died after being hurled off the Fire Ball ride, reportedly is planning on filing a wrongful death suit against KMG.

The teen had just enlisted in the Marine Corps and was to head to basic training next year.

He is one of 22 people, since 2010, to have suffered fatal injuries from an amusement park or carnival attraction.