MIAMI, FL, USA
HK360
BOEING 707-324C
SHORTLY AFTER TAKEOFF, THE #3 ENGINE AND PYLON SEPARATED FROM THE AIRPLANE AS A RESULT OF THE FAILURE OF THE PYLON INBOARD MIDSPAR SUPPORT FITTING. THE FITTING HAD CRACKED DUE TO FATIGUE, AND HAD BEEN CRACKED FOR SOME TIME. THE POINT OF CRACKING WAS NOT VISIBLE FOR INSPECTION ON THE WING. THE FITTING IS THE SUBJECT OF FAA AIRWORTHINESS DIRECTIVE 88-24-10 AND BOEING SERVICE BULLETIN 3183 WHICH REQUIRE VISUAL INSPECTION OF THE MIDSPAR FITTING EACH 1500 FLIGHT HOURS OR 600 CYCLES. THIS INSPECTION HAD BEEN COMPLETED ON THE FAILED FITTING ON JANUARY 2, 1992, 821 FLIGHT HOURS AND 328 CYCLES BEFORE THE FAILURE.
FAILURE OF THE #3 ENGINE PYLON INBOARD MIDSPAR SUPPORT FITTING DUE TO FATIGUE CRACKING WHICH RESULTED IN THE SEPARATION OF THE NUMBER THREE ENGINE AND PYLON. CONTRIBUTING TO THE ACCIDENT WAS THE INADEQUATE INSPECTION REQUIREMENTS OF THE MANUFACTURER AND THE FAA TO DETECT CRACKS IN THE MIDSPAR FITTING.
Source: NTSB Aviation Accident Database
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