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ASN Wikibase Occurrence # 786
Last updated: 29 November 2021
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Type:Silhouette image of generic S61 model; specific model in this crash may look slightly different
Sikorsky S-61N
Owner/operator:KLM Noordzee Helicopters
Registration: PH-NZC
MSN: 61-465
Fatalities:Fatalities: 6 / Occupants: 6
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:North Sea -   Netherlands
Phase: En route
Departure airport:Amsterdam/Schiphol
Destination airport:Chaparral oil rig via Texel
During flight outbound to the oil rig "Chaparral" in the Dutch sector of the North Sea, one of the rotor blades failed halfway along its spar due to fatigue originating at a corrosion pit. The failed blade caused rotor disc imbalance, causing the helicopter to encounter excessive vibrations. These vibrations are likely to have caused an on-board fire. The helicopter became uncontrollable and crashed in the North Sea.

Twelve prior spar cracking cases had occurred. Metallurgical investigation by NLR suggested the OEM's "fatigue design methods were highly unconservative" as actual crack propagation after potential detectability by a pre-flight BIM test was rapid.

Hamburger Abendblatt 11.5.1974



Photo of PH-NZC courtesy

Rotterdam / Maasvlakte-Havenmonding [ Off-Airport ]
24 October 1973; (c) Photo Archive

Carson Helicopters, Perkasie Heliport, PA

Revision history:

21-Jan-2008 10:00 ASN archive Added
19-Dec-2009 08:56 TB Updated
26-Apr-2011 15:54 TB Updated [Time, Phase, Nature, Departure airport, Destination airport, Source, Narrative]
26-Apr-2011 16:01 TB Updated [Destination airport, Narrative]
09-Aug-2014 18:36 Aerossurance Updated [Nature, Destination airport, Source, Narrative]
15-Oct-2015 17:42 jevage Updated [Narrative]
09-Apr-2016 13:56 tipekusair Updated [Photo, ]
11-Aug-2017 11:46 Aerossurance Updated [Source, Narrative]

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