IT'S TIME TO cordon off the Philadelphia Police Department and declare it a crime scene.

At this point, what's long been happening inside that broken department is a crime - against good cops whose reputations are tarnished by dirty cops, against residents who've lost faith in a force that's supposed to protect and serve them, and against the laws that cops are supposed to uphold but that bad cops continue to break . . . and break . . . and break, with little or no consequence.

We can't seem to go more than a few weeks without hearing about a cop getting fired, arrested or benched because of an investigation, while we're being assured that there isn't some systemic problem.

"This [insert latest transgression] does not represent all cops," said [insert name of latest mayor, commissioner, police union president].

The latest black eye for the department came yesterday when six narcotics officers were arrested in a federal corruption probe, charged with robbing, kidnapping and extorting drug suspects for nearly seven years. Five of the six officers pleaded not guilty. The sixth did not have a lawyer and will be arraigned on Monday.

The feds say this band of crooked cops helped themselves to not only half a million dollars, but also to Rolex watches, electronics and a Calvin Klein suit.

Being crooks with expensive tastes wasn't enough. The cops also apparently made a game of their corruption, assigning themselves points for beating drug suspects and even dangling one from a 30-foot-high balcony.

"These officers don't represent the majority of this department," Police Commissioner Charles Ramsey said.

"The overwhelming majority . . . of our officers are hardworking, dedicated and honest," Mayor Nutter said.

Sound familiar?

Can we all agree that we know that? And then can we agree that it doesn't amount to squat? Bad cops, no matter if there's two or 2,000, are a fast-spreading cancer that is proving to be fatal not just to a department but to a city that's constantly being told to trust their police force, that they're getting a bad rap from lying criminals or reporters who are out to get them.

Ramsey knows that. Yesterday, he said the crimes amount to a "malignancy" within the department. He suspended all six with the intent to dismiss.

At least 75 cops have been arrested since 2009, according to a tally by the Daily News.

The way these cops behaved is the stuff that bad, really bad, crime dramas are made of. Except here in Philly, it's real.

Here's a snapshot of what Philly cops have been accused of and arrested for - and sometimes (not often enough) fired or jailed for doing: selling crack, receiving oral sex from prisoners, passing bad checks, pointing guns at a doughnut shop employee and at a church security guard, assaulting ex-wives and girlfriends, driving under the influence, extortion, tax fraud. The list goes on.

The list is so long and the actions so egregious that if this were another department, a neighborhood even, with that many criminals running around, we'd wonder why someone wasn't calling 9-1-1.

That's easy - because the no-snitch culture inside the Police Department is stronger than on any closemouthed Philly street corner. And when cops are talking, too many are making excuses.

These cops arrested yesterday had apparently done these heinous things for years - and lots of people knew about it. In 2012, District Attorney Seth Williams said his office no longer trusted their testimony in drug cases. Hundreds of prior arrests were dismissed, nearly $1 million in lawsuits have been settled, so far.

But those cops weren't pulled off street duty until January, and things didn't get going until one of the corrupt cops flipped and cut a deal for himself. The old adage applies: There is no honor among thieves.

Another problem is the department's inability to punish its own because of bizarre arbitration rulings that don't just protect bad cops, but empower them to keep doing what they're doing because, hey . . . who cares if you punch a woman on video? Who cares if you stop kids walking to a basketball game because they look suspicious? Who cares if you sexually assault someone in your cruiser and the victim actually manages to save some proof?

Just say, as Officer Michael Paige did in 2007, that the victim must have found a used condom from one of his many other dalliances. Paige later returned to work, with back pay.

Ramsey called the latest police scandal "one of the worst cases of corruption that I have ever heard." Wait for it: I'm sure we'll be able to say that again, sooner than we think.

When we can no longer distinguish the good guys from the bad, it's time to stop making excuses and start realizing we have a crisis.

Somebody get the yellow tape. We've got a crime scene on our hands.

Phone: 215-854-5943

On Twitter: @NotesFromHel