Unsecured eyebolt-retaining nut backs off, allowing sheave to drop to rig floor

What happened?

While conducting a run in hole (RIH) with 7 inch completion, the tubing retrievable sub-surface safety valve (TRSSSV) control line sheave fell onto the rig floor.
The 48lbs (22kg) sheave was suspended from the rig floor hydraulic hoist at a 12ft (4m) height.
Why did it happen?

Sheave eyebolt-retaining nut backed off, allowing the sheave to drop to the floor.
No securing, retaining or locking devices to prevent the nut from backing off.
The grease nipple was painted over, thereby preventing proper maintenance of the pin.
Non-compliance to dropped objects prevention scheme (DROPS).
Sheave was certified and had passed the onshore quality assurance (QA) / quality control (QC inspection).The potential for a ‘dropped object’ incident was not identified.
What did they learn?

Before mobilising to rig site, ensure quality assurance (QA) / quality control (QC) inspection standards comply with DROPS guidance and company regulations.
Review planned maintenance systems (PMS) of contractor equipment used at height.
Ask yourself or your crew

How could this happen here?
How can you tell if eyebolt retaining nuts are secured? What securing/retaining/locking devices should we use and when?
What measures do we have on site to ensure that potential dropped objects have been identified before starting work? How can we improve?

Published on 20/07/20 1404 Views

A tubing retrievable sub-surface safety valve (TRSSSV) control line sheave weighing 48lbs (22kg) fell onto the rig floor. The sheave was suspended from a height of 12ft (4m). No injuries were reported.

Courtesy of DROPS