Incident Aerospatiale AS 350BA VH-PTH,
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ASN Wikibase Occurrence # 207113
 
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Date:Wednesday 19 May 1993
Time:09:35
Type:Silhouette image of generic AS50 model; specific model in this crash may look slightly different    
Aerospatiale AS 350BA
Owner/operator:
Registration: VH-PTH
MSN: 1653
Fatalities:Fatalities: 0 / Occupants:
Aircraft damage: Substantial
Location:27km NW of Jindabyne, NSW -   Australia
Phase: Manoeuvring (airshow, firefighting, ag.ops.)
Nature:Agricultural
Departure airport:7km N of Jindabyne, NSW
Destination airport:27km NW of Jindabyne, NSW
Investigating agency: BASI
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The helicopter departed Waste Point helipad at about 0925 to resupply huts with rations and fuel, and to undertake feral animal control. Apart from the cargo, a second crewmember and a passenger were carried. The aircraft approached the first hut (Tin Hut) in clear sky conditions with nil wind. The pilot said he carried out an aerial inspection of the landing area before commencing a landing towards the north. As the aircraft turned onto final approach at an altitude of about 6000 feet, with speed reducing to 20 knots, the engine lost power and the main rotor RPM drooped below the green arc. With about 100 metres left to run to the landing area, and unable to increase engine power, the pilot attempted an autorotation approach. The helicopter landed heavily and bounced before the tail rotor struck the ground. At the time of the accident the aircraft was being flown at about maximum gross weight. Manufacturer information indicated that the aircraft should have been capable of hovering in ground effect with regard to the ambient altitude/temperature conditions. The engine was subsequently removed from the aircraft and bench tested. No operational problems were revealed. The fuel control unit was then removed from the engine and tested. The test revealed that the fuel control unit had a slower than acceptable acceleration response time. This was due to contamination of the fuel control unit with what appeared to be sand. It is considered likely that in a marginal situation of high gross weight and altitude, any delay in fuel control response for increased engine power may have resulted in a considerable loss of height whilst the fuel control unit was responding to demand. The reason why the fuel control unit was contaminated could not be positively determined. The fuel control filter was serviceable and should have prevented the passage of grit into the fuel control unit. However, prior to engine start with the aircraft boost pump operating, fuel from the aircraft fuel supply can bypass the fuel pump and filter. Such contamination of the fuel supply need only have happened once, leaving the fuel control unit contaminated in such a way as to only become apparent at some later stage when engine response was critical.

Accident investigation:
cover
  
Investigating agency: BASI
Report number: 
Status: Investigation completed
Duration:
Download report: Final report

Sources:

https://www.atsb.gov.au/publications/investigation_reports/1993/aair/199301404/
https://www.atsb.gov.au/media/5227297/199301404.pdf

History of this aircraft

Other occurrences involving this aircraft
12 January 1996 VH-PTH 0 Wallemi National Park, NSW sub
Collision with pole or wires

Revision history:

Date/timeContributorUpdates
06-Mar-2018 12:00 Pineapple Added

Corrections or additions? ... Edit this accident description

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