Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Los Angeles, California 90012
Monday, April 20, 1998 21:30 PDT
NTSB Narrative Summary Released at Completion of Accident
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 gas producer turbine components indicated 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 temperatures 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.
NTSB Probable Cause Narrative
An overtemp of the engine during start within 10 hours of the accident, and the failure to report the event to the maintenance facility.
Event Information
| Type of Event | Accident |
| Event Date | 4/20/1998 |
| Event Day of the Week | Monday |
| Time of Event | 2130 |
| Event Time Zone | Pacific Daylight Time |
| Event City | LOS ANGELES |
| Event State | CALIFORNIA |
| Event Country | -- |
| Zipcode of the event site | 90012 |
| Event Date Year | 1998 |
| Event Date Month | 4 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | |
| Event Location Nearest Airport ID | |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | Not pertinent |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 2150 Pacific Daylight Time |
| Direction of event from weather observation facility (degrees) | 220 |
| Weather Observation Facility ID | LAX |
| Elevation of weather observation facility | 126 |
| Distance of event from weather observation facility (units?) | 11 |
| Time Zone of the weather observation | PDT |
| Lighting Conditions | Night/Dark |
| Lowest Ceiling Height | 0 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Unknown |
| Sky Condition for Lowest Ceiling | Broken |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 5 |
| Air Temperature at event time (in degrees celsius) | 14 |
| Dew Point at event time (in degress fahrenheit) | 13 |
| Wind Direction (degrees magnetic) | 250 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 7 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 30 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 2 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 1436 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Apr 21 1998 12:00AM |
| NTSB Notification Time | 815 |
| Fiche Number and/or location -used to find docket information | IMAGE |
| Date of most recent change to record | Feb 26 2001 8:07AM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N87WC |
| NTSB Number | LAX98LA140 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 135: Air Taxi & Commuter |
| Type of Flight Plan filed | Company VFR |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Bell |
| Aircraft Model | 206L-1 |
| Aircraft Series Identifier | 206L-1 |
| Aircraft Serial Number | 45201 |
| Certified Max Gross Weight | 4050 |
| Aircraft Category | Helicopter |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 5 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | 100 Hour |
| Date of Last Inspection | Jan 24 1998 12:00AM |
| Airframe hours since last inspection | 69 |
| Airframe Hours | 3738 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | MICHAEL TAMBURRO |
| Aircraft Owner Street Address | 7240 HAYVENHURST AVENUE |
| Aircraft Owner City | VAN NUYS |
| Aircraft Owner State | CA |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 91406 |
| Operator is an individual? | -- |
| Operator Name | HELINET |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | 16425 HART STREET HANGAR 2 |
| Operator City | VAN NUYS |
| Operator State | CA |
| Operator Country | |
| Operator Zip code | 91406 |
| Operator Code | HEPA |
| Owner has at least one certificate | Yes - certificate holder |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | Unknown |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Non-scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Cargo |
| Type of Flying (Per_Bus / Primary) | Unknown |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | ONT |
| Departure City | ONTARIO |
| Departure State | CA |
| Departure Country | |
| Departure Time | 2110 |
| Departure Time Zone | PDT |
| Destination Same as Local Flt | crash at destination city |
| Destination Airport Code | |
| Destination City | |
| Destination State | |
| Destination Country | |
| Specific Phase of Flight | Approach |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Feb 26 2001 8:07AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 0 |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |