ASN Wikibase Occurrence # 30797
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Saturday 2 January 1999 |
| Time: | 22:15 LT |
| Type: |  Bell 205A-1 |
| Owner/operator: | City Of Los Angeles |
| Registration: | N58126 |
| MSN: | 30136 |
| Year of manufacture: | 1973 |
| Total airframe hrs: | 6361 hours |
| Engine model: | Lycoming T53-13B |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Van Nuys, California -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | Van Nuys, CA (KVNY) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
During a night training flight over mountainous terrain the pilot heard a loud 'clunking' sound, which was accompanied by vibrations. The engine then emitted a loud grinding, metallic grating sound. Simultaneously, warning lights, engine chip lights, and the rpm decay light became illuminated. The pilot lowered the collective and entered an autorotation but did not have sufficient airspeed and altitude to reach a dirt road, so he turned down a canyon and performed a hard flare and near-vertical descent with little forward speed. The helicopter landed hard and came to rest on rough uneven terrain surrounded by trees and high vegetation. Postaccident examination revealed that the engine power turbine as viewed from the exhaust exhibited damage. The number 4 turbine wheel was missing all of its blades and the blades on the number 3 turbine wheel were damaged. Scoring was evidenced on the inside diameter of the turbine case in the area of the Nos. 3 and 4 turbine wheels. All the vanes and inner and outer supports of the second stage power turbine nozzle were displaced and/or missing, and fragments of the outer vane support were torn and distorted. The third stage turbine nozzle exhibited extensive damage on the trailing edges of the vanes and on the shroud/outer housing. Metallurgical examination of the turbine components disclosed features indicative of overload fractures without evidence of material defects or fatigue. The metallurgist concluded that the overall type and degree of engine damage was indicative of a component failure in the second stage power turbine nozzle area; however, the cause of the component failure was not determined.
Probable Cause: A loss of engine power due to an undetermined component failure in the second stage power turbine nozzle area. Factors in the accident were the mountainous/hilly nature of the terrain and the dark night lighting conditions which precluded the pilot from selecting a suitable forced landing area.
Accident investigation:
 |
|
Sources:
NTSB LAX99TA066
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 27-Sep-2008 01:00 | ASN archive | Added |
| 29-Jan-2012 19:36 | Dr. John Smith | Updated [Time, Total fatalities, Total occupants, Other fatalities, Location, Country, Phase, Nature, Departure airport, Source, Damage, Narrative] |
| 25-Nov-2017 12:48 | ASN Update Bot | Updated [Time, Cn, Operator, Nature, Departure airport, Destination airport, Source, Damage, Narrative] |
| 14-Dec-2017 16:55 | ASN Update Bot | Updated [Cn, Operator, Departure airport, Destination airport, Narrative] |
| 08-Apr-2024 11:09 | ASN Update Bot | Updated [Time, Other fatalities, Departure airport, Source, Narrative, Category, Accident report] |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation