mysql - SQL Syntax Error in PHP code - adding together two values -

i keep getting syntax error in mysql code within php file. i'm trying increment/add value in table time variable. if me out i'd appreciate it.

php:

$sql = "update aircraft set maintenanceflighttime = (maintenanceflighttime + $maintenanceduration), aircraftid = $aircraftid"; 

error:

update aircraft set maintenanceflighttime = (maintenanceflighttime + 00:10:00), aircraftid = 8 have error in sql syntax; check manual corresponds mariadb server version right syntax use near ':10:00), aircraftid = 8' @ line 2 

you cannot add string '01:01:01' time column can use addtime()

$maintenanceduration = '00:10:00';  $sql = "update aircraft         set maintenanceflighttime = addtime(maintenanceflighttime, '$maintenanceduration')         aircraftid = $aircraftid";