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Statuts: Accident investigation report completed and information captured
Date:mardi 1 décembre 2020
Heure:09:13
Type/Sous-type:Silhouette image of generic DHC6 model; specific model in this crash may look slightly different
de Havilland Canada DHC-6 Vista Liner 300
Compagnie:Air Sanga
Immatriculation: P2-ASM
Numéro de série: 389
Année de Fabrication: 1973-10-17 (47 years 2 months)
Heures de vol:48082
Cycles:83877
Moteurs: 2 Pratt & Whitney Canada PT6A-27
Equipage:victimes: 0 / à bord: 2
Passagers:victimes: 0 / à bord: 7
Total:victimes: 0 / à bord: 9
Dégats de l'appareil: Substantiels
Lieu de l'accident:Wobagen Airstrip (   Papouasie Nouvelle-Guinée)
Phase de vol: Au décollage (TOF)
Nature:Transport de Passagers Nat.
Aéroport de départ:Wobagen Airstrip, Papouasie Nouvelle-Guinée
Aéroport de destination:Bak Airstrip (AYBB), Papouasie Nouvelle-Guinée
Détails:
A de Havilland Canada DHC-6 suffered an airstrip excursion during takeoff from Wobagen Airstrip, Papua New Guinea.
That morning, the crew had flown to Wobagen on a passenger and cargo charter flight, landing at 08:47. Once on ground, the crew took passengers on board the aircraft and loaded cargo, to conduct a VFR charter flight to Bak Airstrip, located 3.8 nm north-east of Wobagen.
At about 09:13, upon reaching the threshold of strip 12, the captain, who was Pilot Flying, conducted a 180° turn and applied maximum power, transitioning from taxi into take-off roll.
The crew stated that after applying maximum power, the aircraft had a tendency to veer to the right. The captain tried to maintain the aircraft on centreline by using asymmetric thrust, however, as the aircraft accelerated down the strip, the tendency to veer right increased. About 154m down the strip, the aircraft began veering towards the right and tracked away from the centreline. As the aircraft passed the strip boundary (cone markers), with a recorded groundspeed of 40kt the crew aborted the take-off; power to idle and applied full brakes. The aircraft continued forward and veering right. Four seconds later, the aircraft impacted a drain.
The nosewheel subsequently separated from the fork causing the nose to drop and the nose gear subsequently collapsed. The momentum of the aircraft caused it to continue another 8m with the nose dragging across the ground before it impacted the right edge drain.

Wobagen Airstrip is a 600 m long airstrip (12/30) with a slope of 8° to the southeast. Landings are only permitted on runway 30, takeoffs only on runway 12.

Probable Cause:

Contributing Factors:
The crew did not action the appropriate take-off checklist which caused them to miss crucial checks and actions. This caused the engine abnormalities to go unnoticed after take-off power was applied. The abnormal parameters engine parameters remained unnoticed until impact.
The parameters of right engine indicate that it was performing at considerably lower power than the left engine, which was operating to the manufacturer’s specifications. The power difference between the right and left engine created the tendency of the aircraft to veer right.
The right engine T5 Turbine temperature exceeded the limit which shows that the overtemperature condition was sustained by the right engine. The wet deteriorated clay/silt surface did not allow aircrafts tires to gain sufficient traction to follow the control inputs of the PIC as he attempted to steer the aircraft back towards the centreline. As the aircraft accelerated towards the right, it ran over undulated surface. The aircraft continued veering right because the power was not reduced, and the asymmetric effect
continued. With the asymmetric thrust, the undulated slippery surface, the aircraft swerved right. This prompted the PIC to pull power into idle and apply full brakes. After pulling power to idle, and applying full brakes, the aircraft continued with momentum over the significantly slippery surface and impacted the drainage ditch at the edge.

Accident investigation:
Investigating agency: AIC PNG
Status: Investigation completed
Duration: 1 year and 5 months
Accident number: AIC 20-1006
Download report: Final report
Language: English

Sources:
» PNG AIC


Photos

photo of DHC-6-Vistaliner-300-P2-ASM
accident date: 01-12-2020
type: de Havilland Canada DHC-6 Vistaliner 300
registration: P2-ASM
photo of DHC-6-Vistaliner-300-P2-ASM
accident date: 01-12-2020
type: de Havilland Canada DHC-6 Vistaliner 300
registration: P2-ASM
 

Plan
Ce plan montre l'aéroport de départ ainsi que la supposée destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre Wobagen Airstrip et Bak Airstrip est de 7 km (4 miles).
Accident location: Approximate; accuracy within a few kilometers.

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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