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Last updated: 3 December 2021
Statuts:Enquête Officielle
Date:mercredi 19 décembre 1984
Heure:11:08
Type/Sous-type:Silhouette image of generic DH3T model; specific model in this crash may look slightly different
de Havilland Canada DHC-3T Cox Turbine Otter
Compagnie:Cox Aircraft Corp.
Immatriculation: N4247A
Numéro de série: 421
Année de Fabrication: 1964
Heures de vol:7445
Moteurs: 1 Pratt & Whitney Canada PT6A-135
Equipage:victimes: 0 / à bord: 1
Passagers:victimes: 0 / à bord: 2
Total:victimes: 0 / à bord: 3
Dégats de l'appareil: Substantiels
Conséquences: Written off (damaged beyond repair)
Lieu de l'accident:Alki Point, Seattle, WA (   Etats-Unis d'Amérique)
Phase de vol: En vol (ENR)
Nature:Test
Aéroport de départ:Seattle-Boeing Field International Airport, WA (BFI/KBFI), Etats-Unis d'Amérique
Aéroport de destination:Seattle-Boeing Field International Airport, WA (BFI/KBFI), Etats-Unis d'Amérique
Détails:
The re-engined turboprop Otter was performing a test flight maneuvers when problems with the modified fuel system occurred. Ice blocking a fuel vent line caused a partial collapse of the main (engine feed) fuel cell which produced an erroneous fuel quantity reading. In addition, the main tank overflow shutoff valve was leaking, so tank overflow occurred. The fuel overflow caution light illuminated and auxiliary tank fuel pump feed to main automatically shut down. Due to miscalibration, this system overrode pilot attempts to restart aux fuel pumps. The pilot remained in test area troubleshooting rather than an immediate return to base. He finally noted main tank gauge continued to read 'full.' En route to Boeing Field, fuel starvation occurred. He attempted a forced landing in a small athletic field in a residential area rather than ditch in Puget Sound. The aircraft touched down, then bounced across an adjacent street. The arresting action of telephone wires on the vertical fin brought the aircraft to rest in a residential backyard.

Probable Cause:

PROBABLE CAUSE:
fuel system,vent..blocked(total)
fluid,fuel..starvation
CONTRIBUTING FACTORS:
precautionary landing..delayed..pilot in command
terrain condition..none suitable
fuel supply..misjudged..pilot in command
fuel system,tank..distorted
engine instruments,fuel quantity gage..false indication
fuel system,fuel shutoff..leak

Sources:
» NTSB


Photos

photo of DHC-3T-Cox-Turbine-Otter-N4247A
accident date: 19-12-1984
type: de Havilland Canada DHC-3T Cox Turbine Otter
registration: N4247A
photo of DHC-3T-Cox-Turbine-Otter-N4247A
accident date: 19-12-1984
type: de Havilland Canada DHC-3T Cox Turbine Otter
registration: N4247A
photo of DHC-3T-Cox-Turbine-Otter-N4247A
accident date: 19-12-1984
type: de Havilland Canada DHC-3T Cox Turbine Otter
registration: N4247A
photo of DHC-3T-Cox-Turbine-Otter-N4247A
accident date: 19-12-1984
type: de Havilland Canada DHC-3T Cox Turbine Otter
registration: N4247A
 

Plan

Les informations ci-dessus ne représentent pas l'opinion de la 'Flight Safety Foundation' ou de 'Aviation Safety Network' sur les causes de l'accident. Ces informations prélimimaires sont basées sur les faits tel qu'ils sont connus à ce jour.
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