Date:	Saturday 8 June 2024
Time:	11:35
Type:	de Havilland Canada DHC-6 Twin Otter 300 Ikhana
Owner/operator:	Tropicair
Registration:	P2-BBM
MSN:	542
Year of manufacture:	1977
Total airframe hrs:	39322 hours
Cycles:	133123 flights
Engine model:	P&W Canada PT6A-27
Fatalities:	Fatalities: 0 / Occupants: 16
Other fatalities:	0
Aircraft damage:	Minor
Category:	Serious incident
Location:	Kikori Airport (KRI/AYKK), Gulf -   Papua New Guinea
Phase:	Landing
Nature:	Passenger - Non-Scheduled/charter/Air Taxi
Departure airport:	Kerema Airport (KMA/AYKM)
Destination airport:	Kikori Airport (KRI/AYKK)
Investigating agency:	AIC PNG
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
The DHC-6 Twin Otter aircraft was on an IFR passenger flight from Keremato to Kikori, when during the landing roll at the Kikori Airstrip, the aircraft experienced a runway excursion, rolling past the left airstrip boundary, into the drainage ditch where the nosewheel partially bogged into the ground. The nose cone also impacted the ground before the aircraft came to rest. There were no injuries sustained by persons on board.

The aircraft involved was an Ikhana remanufactured Twin Otter X2.

Causes [Contributing factors]:
The investigation identified factors that contributed to the runway excursion at Kikori Airstrip. Pilot actions and inactions interacted with the pre-existing conditions (latent) in the system which breached all defences resulting in the runway excursion.
• The investigation also noted that 4 days after the aircraft was released to service following the installation of a right-hand propeller assembly on P2-BBM and,11 days prior to the serious incident. Four (4) days after the aircraft was released to service, an entry was made in the aircraft's technical log regarding a propeller synchronization issue experienced by the flight crew. The crew had suggested re-rigging. This entry was classified by the flight crew as a Non-
Airworthy Defect (NAD). However, the defect was not assessed within 3 days, as per the Operator’s Maintenance Control Manual requirements by maintenance personnel responsible to determine if the defect was to be rectified or deferred.
• Beta asymmetric condition of the aircraft on landing. After touchdown and initial landing roll, the PIC applied Beta by retarding both power levers aft of the IDLE setting, to slow the aircraft down. Following the Beta application, the aircraft yawed to the left, the PIC then advanced the Left power lever back to IDLE to counter the yaw left. Overcorrection (pilot technique) of the left yaw coupled with a delay in the Beta response caused the aircraft to veer right of centre.
However, due to control inputs (rudder pedal input and asymmetric power application) maintained by the crew, the aircraft after tracking back onto the strip, continued left of the strip.
• Full reverse thrust and braking were ineffective in preventing the impact due to ground controllability issues due to environmental conditions (strip surface damp with standing water and physical characteristics of the strip)

Social media, Facebook, Television, PNG AIC
https://www.aic.gov.pg/investigation/936
https://www.airhistory.net/photo/648667.jpg (photo)
https://www.atsb.gov.au/publications/investigation_reports/2024/report/aa-2024-007

Other occurrences involving this aircraft


6 February 2023

P2-BBM

Tropicair

0

Between Kikori and Balimo, Western

non

Date/time	Contributor	Updates
08-Jun-2024 09:26	Petropavlovsk	Added
08-Jun-2024 09:27	ASN	Updated [Time, Aircraft type, Country, Embed code, Damage, Narrative, ]
08-Jun-2024 09:28	ASN	Updated [Total fatalities, Location, Destination airport, Source, Category, ]
08-Jun-2024 09:36	ASN	Updated [Aircraft type, Narrative, ]
08-Jun-2024 11:20	lagi	Updated [Location, Destination airport, Source, Narrative, ]
09-Jun-2024 04:32	Anon.	Updated [Narrative, ]
09-Jun-2024 04:34	ASN	Updated [Time, Total occupants, Departure airport, Source, Narrative, ]
09-Jun-2024 04:35	ASN	Updated [Narrative, ]
07-Jul-2024 17:11	ASN	Updated [Accident report, ]
09-Jan-2025 13:16	Petropavlovsk	Updated [Source, Narrative, ]
06-Feb-2025 17:37	ASN	Updated [Narrative, Accident report, ]