As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON APPROACH TO LGA, AIRCRAFT LOST BOTH PRESSURE AND QUANTITY IN THE 'A' HYDRAULIC SYSTEM. CREW DECIDED TO DIVERT TO JFK DUE TO LONGER RUNWAYS. FLIGHT 522 MADE AN UNEVENTFUL LANDING IN JFK. NWA MAINTENANCE REPLACED THE RIGHT OUTBOARD FLAP HYDRAULIC POWER UNIT. LEAK AND OPERATIONAL CHECK OK.