Date:	Tuesday 17 July 1990
Time:	16:40
Type:	de Havilland Canada DHC-5D Buffalo
Owner/operator:	Fuerza Aérea Ecuatoriana
Registration:	HC-BFH
MSN:	64
Year of manufacture:	1976
Fatalities:	Fatalities: 0 / Occupants: 2
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	Calgary International Airport, AB (YYC) -   Canada
Phase:	Landing
Nature:	Ferry/positioning
Departure airport:	Billings-Logan International Airport, MT (BIL/KBIL)
Destination airport:	Calgary International Airport, AB (YYC/CYYC)
Confidence Rating:	Information verified through data from accident investigation authorities

Narrative:
When the DHC-5D Buffalo touched down on runway 28 at Calgary International Airport, AB (YYC), the nosegear collapsed. Hydraulic fluid ignited and the aircraft burned out.

The aircraft was operating on a ferry flight from Quito, Ecuador to Calgary, Canada for repairs. Due to a previous accident the landing gear remained down during the ferry flight.

It was concluded that the self-centering mechanism could be forced off centre because of a system malfunction caused by the previous accident or by intentional nosewheel steering input, which would cause enough pressure to shear the pins. The internal damage to the controlcam mechanism allowed the wheels to be off centre at touchdown. Marks on the adjacent sides of the pulleys showed that the cable had been lodged in the space between the two pulleys. Although the extent of this damage was limited, it was representative of damage caused by the previous jungle accident and would have caused the sluggish response to nosewheel commands experienced earlier by the crew. When the weight of the aircraft settled on the misaligned nosewheel, the temporary ferry repairs failed in overload and the nosewheel collapsed.

Aviation Letter 287
ICAO Adrep Summary 3/90 (#8)
Scramble Vol.12, nr.05

Date/time	Contributor	Updates