# Accident 19980420013579A: Bell 206L1, Los Angeles, CA, April 20, 1998

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: April 20, 1998, 21:30 local time
- Place: Los Angeles, CA
- Damage: Substantial damage
- Phase of flight: Level Off Touchdown
- Operating rules: Air taxi and commuter (Part 135)
- Operator: HEPA
- Location: 34.0602° N, 118.2400° W: From the FAA, an estimate near the named town, within about 3 miles
- Nearby events: https://openairdocs.org/map.md?lat=34.0602&lon=-118.2400&mi=10
- Aircraft: N87WC, a cancelled registration (https://openairdocs.org/deregistered/N87WC-2007-07-31) (OpenAirDocs)
- Registry model: Bell Helicopter Textron 206L-1 (registry code 1182107, https://openairdocs.org/model/bell-helicopter-textron-206l-1) (OpenAirDocs)
- Reported make and model: BELL 206L1
- Reported engine: ALLSN 250C28B
- People aboard: 2
- Fatal injuries: 0
- Pilot flight hours: 10,800 total, 1,800 in this make and model, 50 in the last 90 days
- NTSB investigation: [NTSB LAX98LA140](https://openairdocs.org/ntsb/LAX98LA140) (OpenAirDocs)
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/19980420013579A

## Narrative

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

ENGINE FAILURE SHORT FINAL TO ROOF TOP HELIPORT. MADE PAD BU HARD LANDING. ROTORS CHOPPED OFF TAILBOOM. (.4)THE HELICOPTER LOST ENGINE POWER WHILE ON APPROACH TO A ROOFTOP HELIPAD, APPROXIMATELY 50 FEET HIGH AND 50 FEET SHORT OF THE BUILDING.  THE PILOT LANDED THE HELICOPTER ON THE ROOF, SEVERING THE TAIL BOOM AT THE HORIZONTAL STABILIZER. THE SAFETY BOARD CONDUCTED A TEARDOWN EXAMINATION OF THE ENGINE.  DISASSEMBLY OF THE GAS PRODUCER TURBINE SUPPORT FROM THE POWER TURBINE SUPPORT REVEALED A FRACTURED FIRST STAGE TURBINE WHEEL, WHICH DISPLAYED A NINE AIRFOIL CHORDAL SEGMENT OF THE RIM SEPARATED FROM THE LARGER PORTION OF THE WHEEL.  ACCORDING TO THE ALLISON METALLURGIST, BOTH THE FIRST AND SECOND STAGE TURBINE WHEEL BLADES EXHIBITED EVIDENCE OF OPERATION OF TEMPERATURES IN EXCESS OF 2,200 DEGREES FAHRENHEIT.  BOTH PRIMARY AND SECONDARY RIM CRACK FRACTURES EXHIBITED EVIDENCE OF EXPOSURE TO EXTREME TEMPERATURES DURING THE ENGINE START SEQUENCE.  NO EVIDENCE OF ENGINE OIL FIRE WAS OBSERVED ON THE GAS PRODUCER TURBINE COMPONENTS. CHEMICAL ANALYSIS OF THE AFFECTED GA                                                                                                                         S PRODUCER TURBINE COMPONENTS INDICTED CONFORMANCE TO THE SPECIFIED MATERIAL TYPES. THE ALLISON METALLURGIST REPORTED THAT AN OVERTEMPERATURE EVENT OCCURRED AS A RESULT OF A HOT START WHEN BOTH WHEELS WERE NOT AT OPERATING TEMPERATURE; AN OVERTEMPERATURE EVENT OCCURRING WHEN THE ENGINE WAS AT OPERATING TEMERAUTRES WOULD HAVE MELTED THE FIRST STAGE TURBINE WHEEL BLADES.  THE SIZE OF THE GAMMA PRIME AT THE ALTERED LOCATIONS INDICATED THE EVENT OCCURRED APPROXIMATELY WITHIN THE LAST 10 HOURS OF ENGINE OPERATION.  NO HOT START OR OVERTEMPERATURE EVENT WAS REPORTED TO THE MAINTENANCE FACILITY.

## 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 LAX98LA140](https://openairdocs.org/ntsb/LAX98LA140), Apr 21, 1998: Bell 206L-1 (N87WC), Los Angeles, CA, substantial damage. Probable cause: An overtemp of the engine during start within 10 hours of the accident, and the failure to report the event to the maintenance facility.

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.