202620 Complicated procedure foes away

As edited from MAIB (UK) PA summary 1/25

A ferry was on a scheduled run between two ports. The crew planned to carry out a routine test of the stored power launching system with the Fast Rescue Craft (FRC) during the transit. A toolbox talk was conducted before the test and the procedure for the stored power launch procedure was discussed. The vessel was stopped for the drill to take place. 

The vessel-specific procedure for the stored power launch of the FRC consisted of 20 steps, including the operation of seven different ball valves in the davit’s hydraulic system, located on two decks. The crew worked under instruction of a senior officer. When all the valves were thought to be in the correct positions and the boat was slewed out into the launching position, the order was given to operate the launch cable. When the launch cable was pulled, the FRC immediately fell about 9m to the water. Thankfully the FRC was uncrewed, so no injuries were incurred. However, the FRC was damaged beyond repair and had to be replaced.

The FRC was recovered and the launch system inspected. It was found that a valve for draining pressure from the hydraulic system was mistakenly left in the open position. The preliminary investigation found, among other things, that ball valve 9 (BV9) had been mistaken for BV6. The operation of BV9 was not included in the procedure for launching the FRC using stored power. Once BV9 was put in the open position, there was no hydraulic oil pressure available in the system to arrest the fall of the FRC once the launch cable was pulled.

The stored power launch system was subsequently tested using the documented procedure with the correct valve sequence and proven to work without incident.

Lessons learned

• Ideally, a procedure should fit on one page and be as simple as possible.
• In this case, the two valves were close together and the identification label for BV6 was sideways, so that it was not clear which valve it referred to (see photo - labels added to image). 9 and 6 can be confused when the orientation of the sign is not made clear.
• The BV9 valve was in the foreground and painted yellow, thus attracting more attention than the BV6 valve, which was in the background and more restrained in colour.

As edited from MAIB (UK) PA summary 1/25