The first court-ordered class of FDNY trainees — the oldest and most diverse in history — is flaming out.

Halfway through the 18-week Fire Academy course, the dropout rate has hit a sky-high 15 percent and could climb to a third of the 318 who started on July 29, according to insiders.

So far, 48 have dropped out. They include 23 of 123 court-ordered “priority hires,” mainly blacks and Latinos in their 30s and early 40s who took the FDNY entrance exam in 1999 or 2000 but were passed over.

The dropouts also include 23 of 176 FDNY paramedics seeking promotion and two of 20 “open competitive” candidates.

Four of eight women have also bailed. The eight were hailed as the most in an academy class since 1982, when a lawsuit forced the FDNY to bring on the first female firefighters.

In addition, an alarming number of “probies” have been injured — suffering sprains, fractures and other ailments — and put on medical leave, insiders say. Others teeter on the cusp of flunking out because they can’t handle the physical or academic demands.

Dropouts have been pushed to resign, rather than face termination, so they can “recycle” and join the next academy class.

“I’m good at the physical stuff — that wasn’t a problem for me,” said a near-40-year-old who first took the FDNY entrance test in 1999 and jumped at the chance to try again. But the exams, on topics from building construction to hazardous ­materials, tripped him up.

“The only thing was academic. I wanted to stay with it, but the people who run the academy felt my GPA was too low,” he said, adding that he could have improved his grades if given more time.

“I think I could have pulled it off. I left my job to try something new, and they kicked me to the curb.”

An FDNY insider called the 15 percent attrition at the halfway point “huge, an amazing difference from a normal probie class.”

Traditionally, an FDNY academy class loses about 10 percent over the entire training period. In May, 285 of 318 probies graduated from the academy, with a 10.3 percent dropout rate.

Under orders by Manhattan federal Judge Nicholas Garaufis in March 2012, the FDNY altered the composition of its academy classes, taking many candidates from a list of people who he ruled had been unfairly denied.

The result: a class with 66 percent minorities.

The FDNY also launched a program to prevent these new probies from failing, assigning lieutenants to each mentor trainees, giving them pep talks and tips on getting through the course.

Rank-and-file members call it coddling. “Do we have to wipe their noses too?” a veteran grumbled.

“But it’s not working,” an FDNY source said. “A lot of people on the judge’s list are heavier and older. You can’t expect them not to fall out. They’ve been in other lifestyles and careers for years, so it’s hard to stay in top shape.”

The high dropout rate angers the Vulcan Society, the fraternal organization of black firefighters whose lawsuit charging the city with hiring bias led to the court-ordered reforms.

Vulcan Society president John Coombs questioned the FDNY’s commitment to helping minorities succeed.

“Some of those instructors are out to break them,” Coombs said. “It’s psychological warfare.”

He said physical demands, such as running a mile and a half in 12 minutes, are too strictly enforced and said probies who show steady improvement are still being weeded out.

“We’ve never had so many injuries at the academy,” he said. “Are they overtraining the candidates?”

Paul Mannix, president of Merit Matters, a group of firefighters opposed to “quota” hiring, said trainers should not go easy.

“They’re sticking to the standards and not letting people get through who can’t do the job, no matter what their color or gender,” he said.