Hear that whistle blow . . .

YOU might think that if a truck driver concerned about the safety of his rig arranged to have it checked out by the authorities, his employer would be pleased with such conscientiousness. But when Kenneth Prill had his rig inspected after its malfunctioning brakes caused an accident, Meyers Industries Inc. of Tecumseh, Mich., fired him.

And now the National Labor Relations Board has ruled -- for the second time -- that the employer's action is perfectly acceptable under the Taft-Hartley Act. Its reasoning is that Taft-Hartley protects ``concerted actions'' by or on behalf of a group of workers, and not the actions of a lone whistle-blower.

But in a California case in 1975 the NLRB in effect expanded the notion of ``concerted action'' to assume that individuals raising safety concerns, as Mr. Prill did in 1979, have the implied support of other workers. Indeed, in the Prill case another driver assigned to the rig had also complained and said he would not drive it unless it were repaired. And of course a tractor-trailer out of control on a public highway is not just a workplace hazard.

This latest NLRB ruling -- coming after an appeals court asked the board to reconsider its original 1984 decision -- is lamentable.

Nor is the Prill case, which may go to the Supreme Court, an isolated one. Last year, for instance, the NLRB let stand the firing of a shopping mall security guard who protested his employer's policy of merely ejecting drunks from mall property -- without arresting them or notifying police.

Whistle-blowers are as needed as ever, since they identify problems that call out for correction. They need protection, not punishment.