# Accident 19980307002829A: Bell UH1B, Hollister, CA, March 7, 1998

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: March 7, 1998, 09:56 local time
- Place: Hollister, CA
- Damage: Destroyed
- Phase of flight: To Vertical (Helicopter Only)
- Operating rules: Agricultural (Part 137)
- Location: 36.8894° N, 121.2409° W: From the FAA, an estimate near the named town, within about 3 miles
- Nearby events: https://openairdocs.org/map.md?lat=36.8894&lon=-121.2409&mi=10
- Aircraft: N204DR, a cancelled registration (https://openairdocs.org/deregistered/N204DR-2013-08-21) (OpenAirDocs)
- Registry model: Bell UH-1B (registry code 1181410, https://openairdocs.org/model/bell-uh-1b) (OpenAirDocs)
- Reported make and model: BELL UH1B
- Reported engine: LYC T53L11D
- Fatal injuries: 0
- Pilot flight hours: 1,144 total, 40 in this make and model, 102 in the last 90 days
- NTSB investigation: [NTSB LAX98LA108](https://openairdocs.org/ntsb/LAX98LA108) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/19980307002829A

## Narrative

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

TAIL ROTOR GEAR BOX SEPERATED DURING SPRAY RUN. SPIRALLED TO GROUND. (.4)THE PILOT INITIATED A RIGHT TURN, THEN HE FELT AND HEARD A THUMP.  HE LOWERED THE COLLECTIVE AND ATTEMPTED TO STRAIGHTEN FROM THE TURN.  HE FELT A STRONG VIBRATION AND THE NOSE OF THE AIRCRAFT PITCHED DOWN.  A GROUND CREWMAN WHO WITNESSED THE ACCIDENT REPORTED THAT WHILE THE HELICOPTER WAS ABOUT 35 FEET AGL, HE SAW A LARGE PIECE OF THE TAIL AND A ROTOR BLADE FLY OFF THE SHIP, FOLLOWED BY THE TAIL ROTOR HUB ASSEMBLY, THE REMAINING BLADE, AND THE 90-DEGREE GEARBOX. THE HELICOPTER BEGAN A 360-DEGREE RIGHT SPIRAL, MADE 2 1/2 ROTATIONS, AND THEN IMPACTED THE GROUND IN A 30-DEGREE NOSE-DOWN ATTITUDE.  HE FURTHER NOTED THAT THE ENGINE STILL SEEMED TO BE PRODUCING ABOUT 60 PERCENT POWER.  THE TAIL AND TAIL ROTOR GEARBOX WAS FOUND ABOUT 125 FEET FROM THE FUSELAGE.  METALLURGICAL EXAMINATION OF THE VERTICAL TAIL FIN, TAIL ROTOR GEARBOX, AND TAIL ROTOR BLADES DISCLOSED AN AREA OF CHAFING WHICH WORE THROUGH THE VERTICAL FIN'S SPAR AND INITIATED A FATIGUE CRACK.  THE FATIGUE CRACK INITIATED IN AN AREA WHERE THE VERTICAL FIN DRIVESHAFT COVER FASTENED ON THE LEFT SIDE OF THE AIRCRAFT NEAR THE UPPER END.  CHAFING HAD OC      CURRED BETWEEN THE COVER AND THE SPAR, WEARING AWAY THE SPAR. ACCORDING T BELL, THE UH-1B REQUIRES A DAILY INSPECTION TO VISUALLY CHECK THE AREA OF THE UPPER VERTICAL FIN, PER THE AVIATION UNIT TECHNICAL MANUAL, WHERE THE FATIGUE CRACKING OCCURRED.                                                   (-23) WHILE SPRAYING A FIELD AND CLIMBING OUT TO CLEAR TELEPHONE WIRES, THE TAILROTOR AND TRANSMISSION SEPARATED FROM THE TAILBOOM AT APPROX 75 FEET OF ALTITUDE. THE AIRCRAFT SPUN TWO AND ONE HALF TIMES AND STRUCK THE GROUND FLAT (BELLY DOWN).

## 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 LAX98LA108](https://openairdocs.org/ntsb/LAX98LA108), Mar 7, 1998: Bell UH-1B (N204DR), Hollister, CA, destroyed. Probable cause: The failure of the maintenance personnel to recognize and repair the chafed area of the tail rotor driveshaft, which resulted in an in-flight separation of the tail fin and hub assembly.

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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