TEMPSC failure to lower on demand

When some designs of TEMPSC are lowered from an installation, the hydraulic brake is released using stored pressure from a single nitrogen accumulator.

When the brake release lever on a TEMPSC was activated during an exercise, it was found that the accumulator had failed and held no pressure. As a result, the brake could not be released and the TEMPSC could not be lowered.

In the event of an evacuation, the installation could not have been abandoned.

Findings:

• Hydraulic system and nitrogen accumulator pressure were checked every 6 months under a planned maintenance regime, but not during weekly, bi-weekly and monthly planned maintenance.
• The accumulator was not fitted with a gauge or any means to monitor the pressure within the system between checks.
• Whilst the installation had planned to execute change to the system to include a pressure gauge, this had not yet been completed.