# Accident 19970415005959A: Bolkms BK117B1, New York, NY, April 15, 1997

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: April 15, 1997, 17:37 local time
- Place: New York, NY
- Airport: 60th Street Heliport
- Damage: Destroyed
- Phase of flight: To Vertical (Helicopter Only)
- Operating rules: General operating rules (Part 91)
- Location: 40.7590° N, 73.9695° W: From the FAA, an estimate near the named town, within about 3 miles
- Nearby events: https://openairdocs.org/map.md?lat=40.7590&lon=-73.9695&mi=10
- Aircraft: N909CP, a cancelled registration (https://openairdocs.org/deregistered/N909CP-1997-08-29) (OpenAirDocs)
- Registry model: Messerschmitt-Bolkow-Blohm BK 117 B-2 (registry code 5626013, https://openairdocs.org/model/messerschmitt-bolkow-blohm-bk-117-b-2) (OpenAirDocs)
- Reported make and model: BOLKMS BK117B1
- People aboard: 1
- Fatal injuries: 1
- Pilot flight hours: 9,400 total, 3,900 in this make and model, 154 in the last 90 days
- NTSB investigation: [NTSB NYC97FA076](https://openairdocs.org/ntsb/NYC97FA076) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/19970415005959A

## Narrative

As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^.

(.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.

## The NTSB's investigation of this event (1)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB NYC97FA076](https://openairdocs.org/ntsb/NYC97FA076), Apr 15, 1997: Eurocopter MBB-BK117-B2 (N909CP), New York, NY, destroyed, 1 fatal. Probable cause: Fatigue failure of the vertical fin, accelerated by the installation of blind rivets in lieu of solid rivets in the replacement of the yaw SAS mount support, which resulted in the loss of helicopter…

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record.

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