Friday, March 07, 2014

Nepal Airlines de Havilland Canada DHC-6 Twin Otter, 9N-ABU: Tribhuvan International Airport, Kathmandu, Nepal

NAC aircraft makes emergency landing at TIA: Passengers‚ crew safe but airlines left with no plane for domestic flights

 KATHMANDU: Nepal Airlines Corporation will no longer be able to conduct any domestic flight for some time, as the only aircraft that was performing inland operations was grounded today following engine failure.

The state-owned airline company’s Twin Otter was grounded after it encountered technical problems in the right engine. The fault was detected soon after it took off for Lamidanda from Tribhuvan International Airport in Kathmandu this afternoon.

“The aircraft was only around 100 feet above the ground when the right engine encountered problem,” Deputy Director at TIA’s Rescue Coordination Centre Bimalesh Karna told THT. Captain Sanjay Vaidya, who was the aircraft’s

commander, then shut down the right engine and used the left one to land the aircraft back at TIA, a reliable NAC source said. All 15 passengers, including two infants and one child, and three crew members, including co-pilot Prashant Rai, are safe.

Although nothing unfortunate happened, the incident has left NAC with no plane to conduct domestic flights. “Our sales department has informed this to all travel agencies and asked them to cancel all bookings,” NAC Spokesperson Ram Hari Sharma said.

NAC, which used to own 12 Twin Otters in its heyday, was operating around 22 domestic flights with only two aircraft for the last several months, until one of them crashed at Masine Lek of Khachikot in Arghakhanchi last month. Since then it had halved its domestic operations, severely affecting passengers of hilly and remote areas that are not connected by roads. “We are not sure how long it will take to fix the engine so that domestic operations can be resumed,” Sharma said.

Although it is not known what caused the engine failure, people at NAC’s flight safety department suspect ‘compressor stall’—a situation that occurs due to abnormal flow of air into the compressor. As per experts, after propellers of aircraft suck the air in, the air is compressed by a compressor following which energy is developed in the combustion chamber. The exhaust turbine then develops power and pushes the aircraft forward. “During this process, the air flow must have been interrupted

and may have even caused damage to compressor blades, which caused the engine failure,” the NAC source said.

This, however, should not mean the aircraft’s engine was old, he added. The engines of the aircraft, which was brought to Nepal in mid-1980s, had undergone an overhaul recently, and the one that failed today had completed only 250 hours of flight, the source said, adding engine overhauls are conducted after completion of 4,000 hours of flight.

Tragedy averted

KATHMANDU: The aircraft was only around 100 feet above the ground when the right engine encountered problem. Immediate emergency landing with no casualty was possible because TIA’s runway is about 3,000 metres in length and Twin Otter can land on runways as short as 500-600 metres. The risk might have gone up if the same incident had occurred in some of the rural airports where airstrip length is not even 600 metres.

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