# Accident 19980420007279A: Bell 206B, Grand Canyon, AZ, April 20, 1998

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: April 20, 1998, 16:15 local time
- Place: Grand Canyon, AZ
- Airport: Grand Canyon National Park
- Damage: Substantial damage
- Phase of flight: Pwr On Vertical Ldng/Rtrcrft
- Operating rules: General operating rules (Part 91)
- Operator: PG9A
- Location: 36.0295° N, 112.0196° W: From the FAA, an estimate near the named town, within about 3 miles
- Nearby events: https://openairdocs.org/map.md?lat=36.0295&lon=-112.0196&mi=10
- Aircraft: N8533F, a cancelled registration (https://openairdocs.org/deregistered/N8533F-2013-03-04) (OpenAirDocs)
- Registry model: Bell 206B (registry code 1181511, https://openairdocs.org/model/bell-206b) (OpenAirDocs)
- Registry engine: Allison 250 SER 400HP (registry code 03013, https://openairdocs.org/engine/allison-250-ser-400hp) (OpenAirDocs)
- Reported make and model: BELL 206B
- Reported engine: ALLSN 250C20B
- People aboard: 2
- Fatal injuries: 0
- Pilot flight hours: 4,200 total, 1,700 in this make and model, 110 in the last 90 days
- NTSB investigation: [NTSB LAX98LA139](https://openairdocs.org/ntsb/LAX98LA139) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/19980420007279A

## Narrative

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

HARD GROUND IMPACT DURING PRACTICE AUTOROTATION. FUEL CONTROL GOVERNOR SURGED AND SLOW RESPONSE IN POWER RECOVERY. (.4)THE INSTRUCTOR PILOT AND NEW COMPANY PILOT WERE PRACTICING AUTOROTATIONS, WHICH WERE TERMINATING IN A POWER-RECOVERY. THE FLIGHT INSTRUCTOR DEMONSTRATED A STRAIGHT-IN AUTOROTATION AND SAID THAT THE GOVERNOR LAGGED BEHIND BUT STAYED IN THE GREEN RANGE.  THE INSTRUCTOR STATED THAT THIS WAS TYPICAL OF THIS PARTICULAR HELICOPTER AND THAT HE DIDN'T CONSIDER THE GOVERNOR LAG UNUSUAL.  THE INSTRUCTOR THEN HAD THE DUAL STUDENT SET UP FOR A 180-DEGREE AUTOROTATION.  DURING THE MANEUVER HE TOLD THE STUDENT THAT HE WAS READY TO ROLL ON THE THROTTLE AT 200 FEET AGL.  HE STATED THAT AT 50 FEET AND 50 TO 55 KNOTS, THE PILOT FLARED THE HELICOPTER AND AT 15 FEET HE HAD THE PILOT PULL IN MORE COLLECTIVE.  AT THIS POINT, THE INSTRUCTOR PULLED IN SOME COLLECTIVE HIMSELF.  HE STATED THAT THE TORQUE GAUGE DID NOT MOVE AND THAT IT SOUNDED LIKE THE ENGINE SOUND WAS DRAGGING DOWN AND THE RPM'S IN THE DUAL TACH DECAYED.  THE FLIGHT INSTRUCTOR PROCEEDED TO TAKE THE CONTROLS AND LEVE                                                                                                              L THE AIRCRAFT. THE AIRCRAFT LANDED HARD AND CAME TO A COMPLETE STOP.  AFTER THE AIRCRAFT WAS SHUT DOWN, THE TAIL BOOM FAILURE CAN OCCUR IN AUTOROTATIONS WHERE TOUCHDOWN OCCURS AT 70 PERCENT MAIN ROTOR SPEED DUE TO A RESONANCE RESPONSE TO THE STRUCTURE TO THE MAIN ROTOR.  A POSTACCIDENT TEST OF THE GOVERNOR FUNCTION WAS PERFORMED.  POWER CHECKS WERE DONE TO DUPLICATE AN AUTOROTATION AND THE TESTS REVEALED THAT THE ENGINE WAS SLOW TO ACCELERATE AND THA GOVERNOR SURGED WITH CONTINUAL FLUCTUATION OF NG READINGS.

## 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 LAX98LA139](https://openairdocs.org/ntsb/LAX98LA139), Apr 20, 1998: Bell 206B (N8533F), Grand Canyon, AZ, substantial damage. Probable cause: The malfunction and erratic speed control of the engine's governor, and the flight instructor's delayed remedial action.

## Other reports on N8533F (2)

Matched to the same aircraft by N-number and date.

- [Accident 20101103049709A](https://openairdocs.org/incident/20101103049709A), Nov 3, 2010: Bell 206B (N8533F), Meeker, CO, Destroyed, 1 fatal. [privacy data omitted] Was PIC of a Bell 206, N8533F flying a part 91 pipeline patrol. They were approx. 10 miles north west of Meeker co. at approx 1500 local…
- [Accident 19790803032509A](https://openairdocs.org/incident/19790803032509A), Aug 3, 1979: Bell 206B (N8533F), Grand Canyon, AZ, Substantial damage. Engine quit en flight. Made autorotate hard landing. Defective engine-driven fuel pump. Inadequate maintenance.

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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