Date:	Friday 11 March 1983
Time:	14:52
Type:	Sikorsky S-61N-II
Owner/operator:	British Airways Helicopters
Registration:	G-ASNL
MSN:	61220
Year of manufacture:	1963
Fatalities:	Fatalities: 0 / Occupants: 17
Other fatalities:	0
Aircraft damage:	Substantial
Location:	North Sea, 77nm North East of Aberdeen -   United Kingdom
Phase:	En route
Nature:	Offshore
Departure airport:	Claymore platform
Destination airport:	Aberdeen Airport (ABZ/EGPD)
Investigating agency:	AIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Ditched into the North Sea 77 nautical miles North East of Aberdeen and sank after main rotor gearbox failure. All 17 persons on board (crew of 2 and 15 passengers) escaped unhurt, and were rescued. According to the following extract from the official AAIB report into the accident:

"SHORTLY AFTER DEPARTURE FROM AN OIL RIG THE CREW HEARD A LOUD BANG & EXPERIENCED VIBRATION FROM THE MAIN ROTOR TRANSMISSION. AT THE SAME TIME THE No.1 ENGINE WAS SEEN TO RUN DOWN & STOP. A DISTRESS CALL WAS TRANSMITTED & A CONTROLLED DITCHING WAS COMPLETED WITH THE HELICOPTER STABILIZED ON ITS EMERGENCY FLOTATION GEAR. HOWEVER, DURING DEPLOYMENT, BOTH LIFE RAFTS WERE PUNCTURED & RENDERED UNUSABLE BY SHARP PROJECTIONS ON THE HULL OF THE A/C. THE HELICOPTER WAS NOT DAMAGED IN THE ACCIDENT BUT LATER SANK AS A RESULT OF DAMAGE SUSTAINED DURING AN ATTEMPTED RECOVERY.

THE REPORT OF THE AAIB CONCLUDES THAT THE ACCIDENT WAS CAUSED BY FAILURE, IN FATIGUE, OF A SPUR GEAR IN THE MAIN ROTOR TRANSMISSION GEARBOX WHICH RESULTED IN A RUPTURE OF THE GEARBOX CASING & LOSS OF THE TRANSMISSION LUBRICATION OIL"

UK registration G-ASNL cancelled 31/10/1983 as "sold to United States of America". Wreckage recovered and was sold to Carson Helicopters as N4503E; rebuilt to S-61 Shortsky.

1. AAIB: https://assets.digital.cabinet-office.gov.uk/media/5422fd0840f0b6134200080d/Sikorsky_S61N_G-ASNL.pdf
2. CAA: https://www.caa.co.uk/docs/HistoricalMaterial/G-ASNL.pdf
3. https://www.helis.com/database/cn/21224/
4. http://www.griffin-helicopters.co.uk/accidentdetails.aspx?accidentkey=14442

British Airways helicopter Sikorsky S-61N, G-ASNL ditched in the North Sea, 77 nm North-east of Aberdeen on 11 March 1983

Date/time	Contributor	Updates
21-Dec-2012 11:59	TB	Added
21-Dec-2012 12:04	TB	Updated [Narrative, ]
01-Jun-2013 17:24	Dr. John Smith	Updated [Time, Source, Embed code, Narrative, ]
01-Jun-2013 17:34	Dr. John Smith	Updated [Embed code, Narrative, ]
12-Jun-2013 16:27	TB	Updated [Location, Source, Embed code, Narrative, ]
14-Jun-2013 14:04	helis	Updated
14-Jun-2013 18:04	harro	Updated [Damage, ]
16-Jul-2013 15:01	TB	Updated [Location, ]
26-Oct-2015 22:18	Dr.John Smith	Updated [Time, Location, Source, Embed code, Narrative, ]