Date:	Friday 17 February 2023
Time:	09:00 UTC
Type:	Airbus Helicopters H-175B
Owner/operator:	Offshore Helicopter Services UK Ltd
Registration:	G-MCSH
MSN:	5034
Year of manufacture:	2018
Fatalities:	Fatalities: 0 / Occupants:
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Serious incident
Location:	Elgin PUQ Installation, Central North Sea -   United Kingdom
Phase:	Standing
Nature:	Offshore
Departure airport:	Elgin-Franklin Oil Platform, North Sea, 130 miles East of Aberdeen
Destination airport:	Aberdeen International Airport (ABZ/EGPD)
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
An Airbus H175 helicopter operated by Offshore Helicopter Services UK (OHS) has suffered significant damage. G-MCSH flew a 130-mile sector to the Elgin installation on the North Sea, due east of Aberdeen on the morning of Friday 17th February, departing just before 7.30am. Unfortunately, the aircraft had a tail rotor issue prior to its return flight, and the tail rotor chip light illuminated – stranding the helicopter on the rig. While parked on the Elgin rig, Storm Otto came through and snapped at least three of its five blades off close to the root.


AAIB Conclusion
The investigation highlighted issues with wind reporting on the Elgin PUQ and other offshore platforms. No cause for these inaccuracies could be provided which remains a problem for operations relying on accurate wind information, especially when nearing high wind limits. Improved quality assurance would assist in identifying potential causes and allow notification where helicopter operations may be affected.
The cause of the TGB chip light would not have prevented continued operation of the helicopter, but this information was not known at the time and shutting the helicopter down on the offshore helideck was considered appropriate, despite the oncoming storm conditions. An opportunity to identify the failure of the rotor brake prior to departure was missed which became a significant factor in the sequence of events leading to the blade failures. This led to an inability to apply the blade ties after shutdown on the platform, although these would not have necessarily prevented damage to the blades occurring due to the strength of the winds experienced. The investigation identified inappropriate and missing mooring equipment being kept on the platform. The HCA is taking action to address this, but will require the co-operation of the operator and helideck owner in doing so. There were also no blade mooring poles being carried on the aircraft in view of the high winds.
The rotor brake was found to be partially seized because of organic material build up on one of the brake pad guides, allowing restricted movement of the mobile brake pad and reduced braking force to slow and stop the rotor system when the rotor brake was applied.
The cause of the organic material build up could not be identified.
A review of the environmental reports related to the construction of the Elgin PUQ and later addition of an accommodation block raised issues over exceedances of CAA limits and a lack of operational procedures to compensate. Both the operator and current management within the HCA were unaware of this information and they will now be carrying out their own review.
The loss of chronological flight data recording was caused by the helicopter’s input power profile providing insufficient time for the FA5000 CVFDR brownout capacitors to achieve their fully charged state. A software modification to the CVFDR is available that corrects this. The CVFDR ARINC717 loop back signal was also found to be out of specification, for which the helicopter manufacturer’s analysis showed that it resulted in a loss of flight data
at 10 minute intervals. The helicopter manufacturer has provided a change to the flight recording system and intends to improve its Helionix software. The CVFDR manufacturer initially advised it was developing a hardware modification to resolve the loss of data, but subsequently advised it had stopped this activity as it considered the root cause may be due to other system integration issues. It stated its investigation was ongoing.

1. AAIB 1st Anniversary Statement 17 February 2024: https://www.gov.uk/government/news/anniversary-statement-ec175-b-g-mcsh
2. https://helihub.com/2023/02/20/airbus-h175-blades-snapped-off-at-the-root/
2. https://www.energyvoice.com/oilandgas/north-sea/484468/helicopter-stranded-on-totals-elgin-platform-after-blades-snap-during-storm-otto/
3. https://www.pprune.org/rotorheads/651472-helicopter-blades-damaged-storm-otto.html
4. https://www.energyvoice.com/health-safety-environment/491335/storm-otto-helicopter-totalenergies/
5. https://www.flightradar24.com/data/aircraft/g-mcshhttps://www.helis.com/database/cn/51138/

https://www.gov.uk/aaib-reports/aaib-investigation-to-airbus-helicopters-ec175-b-g-mcsh

Airbus G-MCSH Arriving at Sumburgh, Shetland Isands 25 January 2022

Dyce-based helicopter blades snap on rig during storm Otto
byu/wrath_blast_rewind inAberdeen

Date/time	Contributor	Updates
16-Jun-2024 06:53	Dr. John Smith	Updated [Source, Narrative, ]
16-Jun-2024 06:53	ASN	Updated [Aircraft type, ]
21-Apr-2025 17:56	Anon.	Updated [Embed code, ]
22-May-2025 11:18	Anon.	Updated [Aircraft type, Source, ]
22-May-2025 11:23	ASN	Updated [Time, Aircraft type, Narrative, Accident report, ]