Date:	Wednesday 25 August 2021
Time:	16:18 LT
Type:	Enstrom 280FX Shark
Owner/operator:	Private
Registration:	G-OJBB
MSN:	2084
Year of manufacture:	1999
Engine model:	Lycoming HIO-360-F1AD
Fatalities:	Fatalities: 0 / Occupants: 1
Aircraft damage:	Destroyed
Category:	Accident
Location:	Rhobell Fawr, near Llanfachraeth, Snowdonia, Gwynedd, Wales -   United Kingdom
Phase:	En route
Nature:	Private
Departure airport:	Chester/Hawarden Airport (CEG/EGNR)
Destination airport:	Chester/Hawarden Airport (CEG/EGNR)
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
An Enstrom 280FX Shark crash landed at the summit of Rhobell Fawr, near Llanfachraeth, after suffering mechanical failure.

During a flight from Hawarden Airport, the pilot noticed a stone obelisk when approaching Rhobell Mountain and decided to take a closer look. Having flown past at 20 metres, he brought the helicopter into a hover. However, the helicopter suffered a loss of thrust from the tail rotor while hovering close to the ground near a mountain top, resulting in a loss of control and a hard landing. The pilot vacated the cockpit and suffered minor injuries.

The investigation found that the tail rotor gearbox revealed damage to the bevel gears and failure of a bearing, which was consistent with inadequate cooling and a lack of lubrication. In addition, there were inconsistencies in the way maintenance was performed on the tail rotor gearbox, compared to the helicopter manufacturer’s maintenance instructions. It is likely that insufficient oil was added to the tail rotor gearbox when it was serviced 25 flying hours prior to the accident.

As a result of the AAIB’s findings, three Safety Recommendations have been made relating to information in the helicopter Maintenance Manual regarding the required oil quantity and maintenance servicing interval for the tail rotor gearbox.

=Safety Recommendations=
*Safety Recommendation: 2023-001:
It is recommended that Enstrom Helicopter Corporation amends the wording in Section 4-15 of the Enstrom F28F and 280F series Maintenance Manual, to clearly identify the minimum and maximum oil levels required for tail rotor gearbox operation.
*Safety Recommendation: 2023-002
It is recommended that Enstrom Helicopter Corporation amends the Enstrom F28F and 280F series Maintenance Manual to achieve a consistent reference to the required quantity of oil for the tail rotor gearbox.
*Safety Recommendation: 2023-003
It is recommended that Enstrom Helicopter Corporation amends the 100 hr/Annual checklist and other related sections of the Enstrom F28F and 280F seriesMaintenance Manual to clearly reflect the intended periodicity for changing the tail rotor transmission oil.

=Damage to airframe=
Per the above AAIB Report "airframe damaged beyond economic repair"

1. South Snowdonia Search & Rescue Team facebook page 25 August 2021
2. AAIB Final Report: https://assets.publishing.service.gov.uk/media/63a1bd6ce90e0758710c2711/Enstrom_280FX_G-OJBB_02-23.pdf
3. https://www.dailypost.co.uk/news/north-wales-news/helicopter-pilots-lucky-escape-after-21487281
4. https://www.northwaleschronicle.co.uk/news/19560346.helicopter-crash-lands-snowdonia/
5. https://www.gov.uk/government/publications/aaib-current-field-investigations/air-accidents-investigation-branch-current-field-investigations
6. https://www.gov.uk/government/news/enstrom-280fx-g-ojbb-anniversary-statement
7. https://en.wikipedia.org/wiki/Rhobell_Fawr

The AAIB has published a report into an Enstrom 280FX (G-OJBB) after it suffered a loss of thrust from the tail rotor near Rhobell Fawr, Dolgellal, Gwynedd.
Read the report: https://t.co/J6VqRhUtum#AviationSafety pic.twitter.com/lLEUXWIDEj

— AAIB (@aaibgovuk) January 5, 2023

Enstrom 280FX Shark G-OJBB at Gloucestershire Airport 28 July 2016, 11:05 LT: Enstrom 280FX Shark G-OJBB at Sleap, Shropshire 1June 2021

Date/time	Contributor	Updates
05-Sep-2021 06:56	edk94	Added
05-Sep-2021 15:44	gerard57	Updated [Operator, Nature, Source]
05-Sep-2021 16:14	RobertMB	Updated [Aircraft type, Registration, Cn, Source, Narrative]
06-Sep-2021 13:35	Dr. John Smith	Updated [Time, Location, Source, Embed code, Narrative, Category]
06-Sep-2021 13:40	Dr. John Smith	Updated [Departure airport, Embed code]
06-Sep-2021 13:49	Dr. John Smith	Updated [Embed code, Narrative]
13-Mar-2022 17:31	Dr. John Smith	Updated [Embed code]
02-Oct-2022 20:56	Dr. John Smith	Updated [Source, Narrative]
23-Jun-2023 19:10	harro	Updated [[Source, Narrative]]