Date:	Tuesday 3 March 2020
Time:	14:30 UTC
Type:	Eurocopter AS-350B-2 Ecureuil
Owner/operator:	PLM Dollar Group t/a PDG Helicopters
Registration:	G-PDGF
MSN:	9024
Year of manufacture:	2000
Fatalities:	Fatalities: 0 / Occupants: 1
Other fatalities:	0
Aircraft damage:	None
Category:	Serious incident
Location:	Glencoe, Lochaber, Argyll, Highlands, Scotland -   United Kingdom
Phase:	Initial climb
Nature:	Cargo
Departure airport:	Glencoe, Lochaber, Argyll, Highlands, Scotland
Destination airport:
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
AAIB investigation to Eurocopter AS-350B-2 Ecureuil, G-PDGF: Inadvertent release of underslung load, Glencoe, Lochaber, Argyll, Highlands, Scotland 3 March 2020. The incident was the subject of an AAIB Investigation, and the following is the summary from the AAIB report, published on 9 July 2020:

"Synopsis
During the refurbishment of an electricity line, G-PDGF was carrying an underslung load consisting of a 700 kg wooden pole which was then inadvertently released. The pole broke into two pieces when it struck a steep hill approximately 200 m from a minor public road, but clear of any built-up areas and third parties. There was no damage to the helicopter or lifting equipment. The operator considered the most probable cause for the inadvertent release of the load was that the sling, which was carrying the load, was not positioned correctly in the helicopter’s hook which was of the spring-loaded keeper design. As a result of this incident, the operator is continuing to phase out the use of this design of hook for most of its operations and has changed its procedures so that only the operator’s employees are permitted to load the hook when spring-loaded keeper hooks are used.

Analysis
The operator’s assessment of the incident considered four causes for the inadvertent release of the load: the inadvertent release of the electrically-operated hook by the pilot; the release of the hook due to an electrical malfunction; and two causes, similar in nature, that could cause the spring-loaded keeper to be forced open during flight.

The operator considered the most likely cause was that, when the load was hooked on at the storage facility, the sling carrying the load was not positioned fully into the semi-circular recess on the load bearing beam which normally provides additional protection against any movement of the sling. This would have allowed the sling to move during flight and, as the load spun rapidly, to overcome the resistance of the spring-loaded keeper thereby releasing the load. The operator considered it unlikely that the load was released inadvertently by the experienced pilot because the release system requires two independent switches on the cyclic to be depressed simultaneously to command a release. The hook and its release system were electrically checked by the operator’s engineering department and no faults were found; however, an intermittent fault could not be ruled out as an alternative cause for the inadvertent release of the load.

Conclusion
The most probable cause for the inadvertent release of the load was that the load had not been positioned correctly across the hook’s load bearing beam when the load was hooked on. At this time, the client’s employee, although having been trained in underslung load lifting operations, was working alone and was not being directly supervised. However, an intermittent fault could not be ruled out as an alternative cause for the release.

Safety action
As a result of this incident, the operator is taking the following action:

The operator is continuing to phase out the use of hooks with spring-loaded keepers in favour of using keeperless hooks for most of its operations. Additionally, the operator has amended its procedures so that, if spring-loaded keeper hooks are used, only the operator’s employees will carry out loading operations. The operator advised that, as keeperless hooks require the use of two hands, it will retain a few spring-loaded keeper hooks for tasks such as lifting a load from a scree-covered hillside, where using both hands poses a greater risk to the loader

Damage Sustained to airframe
Per the AAIB Report "No damage to the helicopter or lifting equipment, underslung load destroyed". As the helicopter was undamaged, it was quickly returned to service.

Glencoe or Glencoe Village (Gaelic: A’ Chàrnaich) is the main settlement in Glen Coe in the Lochaber area of the Scottish Highlands. It lies at the north-west end of the glen, on the southern bank of the River Coe where it enters Loch Leven (a salt-water loch off Loch Linnhe).

1. AAIB Report 9 July 2020: https://assets.publishing.service.gov.uk/media/5f1ad0853a6f407278c983d7/Eurocopter_AS350B2_G-PDGF_07-20.pdf
2. https://airport-data.com/aircraft/G-PDGF.html
3. https://airport-data.com/aircraft/G-FROH.html
4. https://www.planelogger.com/Aircraft/Registration/G-PDGF/
5. https://www.helis.com/database/cn/25859/
6. https://en.wikipedia.org/wiki/Glencoe,_Highland

Built 2000. First registered in the UK (from new) as G-FROH on 16 May 2000. Sold to PLM Dollar Group 14 December 2006 and re-registered as G-PDGF. Nominal re-registration 25 May 2007 to PLM Dollar Group t/a PDG Helicopters (same owners under a slightly different trading name).

As per the AAIB Report, G-PDGF was undamaged in the incident at Glencoe on 3 March 2020 (although the underslung load was destroyed) and the helicopter was returned to service. Total flying hours accumulated on the airframe: 13,399 as at 15 January 2024

G-PDGF: Eurocopter AS350B2 Transporting cement from Sandlodge to Mousa Pier, 10 August 2020

Date/time	Contributor	Updates
01-Oct-2024 06:32	Dr. John Smith	Added
01-Oct-2024 06:33	ASN	Updated [Accident report, ]