<?php
$array = array(
        'error' => array(
                'sql' => 119, 'fatal' => 8, 'reported' => 15
        )
);

function pimpmyarray($a,$depth){
    foreach($a as $k=>$v){
        if (is_array($v)){
            $a[$k]=pimpmyarray($v,$depth+1);
        } else {
            if ($k=='fatal'){
                $a[$k]=5;
            }
        }
    }
    return $a;
}

echo "Input array: ";
print_r($array);
echo "Output array: ";
print_r(pimpmyarray($array,0));
?>