What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(.4)After climbing about 30' after takeoff, loud bang was heard, then helicopter (hel) rotated right, descended, struck edge of heliport, and descend into east river. Pilots evacuated underwater; passengers remained in cabin until retrieved by divers. Throttles were found in flight position. Investigation revealed upper 3' of vertical fin failed and separated from tail boom, along with tail rotor assembly. Exam of fractures revealed fatigue cracking of spar, frame assembly, stiffener rib, and skin on left side of fin. About 4-1/2 yrs before accident, yaw sas actuator mounting plate (originally attached to vertical fin with solid rivets) developed a crack and was replaced using blind rivets. Neither the repair nor substitution of rivets was addressed in manufacturer's maintenance manual. Info was found that blind rivets had about 1/2 the fatigue strength of solid rivets. No specfic reference by manufacturer or FAA was found to allow use of blind rivets for the repair. According to FAA advisory circular (ac) 65-9, bulbs, cherrylock rivets (a specific brand of blind rivets) were interchangeable structurally with solid rivets; however, ac 43.13 did not allow substitution with out manufacturer's approval. Interviews with previous passengers disclosed most were not aware of emergency exits in cabin or how to operate them; life vest (in sealed packets) were available, but not used. Procedures for loss of tail rotor thrust required emergency shutdown of both engines. Pic's last emergency training was about 3-1/2 years before accident.
As the FAA filed it
(.4)AFTER CLIMBING ABOUT 30' AFTER TAKEOFF, LOUD BANG WAS HEARD, THEN HELICOPTER (HEL) ROTATED RIGHT, DESCENDED, STRUCK EDGE OF HELIPORT, AND DESCEND INTO EAST RIVER. PILOTS EVACUATED UNDERWATER; PASSENGERS REMAINED IN CABIN UNTIL RETRIEVED BY DIVERS. THROTTLES WERE FOUND IN FLIGHT POSITION. INVESTIGATION REVEALED UPPER 3' OF VERTICAL FIN FAILED AND SEPARATED FROM TAIL BOOM, ALONG WITH TAIL ROTOR ASSEMBLY. EXAM OF FRACTURES REVEALED FATIGUE CRACKING OF SPAR, FRAME ASSEMBLY, STIFFENER RIB, AND SKIN ON LEFT SIDE OF FIN. ABOUT 4-1/2 YRS BEFORE ACCIDENT, YAW SAS ACTUATOR MOUNTING PLATE (ORIGINALLY ATTACHED TO VERTICAL FIN WITH SOLID RIVETS) DEVELOPED A CRACK AND WAS REPLACED USING BLIND RIVETS. NEITHER THE REPAIR NOR SUBSTITUTION OF RIVETS WAS ADDRESSED IN MANUFACTURER'S MAINTENANCE MANUAL. INFO WAS FOUND THAT BLIND RIVETS HAD ABOUT 1/2 THE FATIGUE STRENGTH OF SOLID RIVETS. NO SPECFIC REFERENCE BY MANUFACTURER OR FAA WAS FOUND TO ALLOW USE OF BLIND RIVETS FOR THE REPAIR. ACCORDING TO FAA ADVISORY CIRCULAR (AC) 65-9, BULBS, CHERRYLOCK RIVETS (A SPECIFIC BRAND OF BLIND RIVETS) WERE INTERCHANGEABLE STRUCTURALLY WITH SOLID RIVETS; HOWEVER, AC 43.13 DID NOT ALLOW SUBSTITUTION WITH OUT MANUFACTURER'S APPROVAL. INTERVIEWS WITH PREVIOUS PASSENGERS DISCLOSED MOST WERE NOT AWARE OF EMERGENCY EXITS IN CABIN OR HOW TO OPERATE THEM; LIFE VEST (IN SEALED PACKETS) WERE AVAILABLE, BUT NOT USED. PROCEDURES FOR LOSS OF TAIL ROTOR THRUST REQUIRED EMERGENCY SHUTDOWN OF BOTH ENGINES. PIC'S LAST EMERGENCY TRAINING WAS ABOUT 3-1/2 YEARS BEFORE ACCIDENT.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.