As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT RETURNED TO PLATFORM AS A CONSEQUENCE THAT BEFORE TAKEOFF THE RIGHT GENERATOR FREQUENCY AND AHRS-2 WERE OUT OF SERVICE. THE REPORT WAS DEFERRED IAW MEL 24-1-B. DURING OVERNIGHT CHECK, THE RIGHT CSD AND OIL HEAT EXCHANGER WERE REPLACED IAW MM 24-10-01/-03, RESPECTIVELY AND THE AHRS-2 WAS TESTED IAW MM 34-21-10, BEING CORRECT. DEFERRED REPORT WAS CLOSED.