As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - FLT 3537 - AFTER TAKEOFF, LANDING GEAR SELECTED TO UP POSITION. GEAR DID NOT RETRACT. CREW SELECTED LANDING GEAR TO DOWN POSITION AND RETURNED TO DFW. PERFORMED OPERATIONAL CHECK OF LANDING GEAR. NO DEFECTS NOTED. DISCREPANCY COULD NOT BE DUPLICATE. AIRCRAFT RETURNED TO SERVICE. (M)