The Bureau of Safety and Environmental Enforcement (BSEE) draws lessons learned from the investigation of a fire on an offshore platform in the Gulf of Mexico involving a rental generator and air shutoff valves.
The incident stemmed from a malfunction in the engine’s air shutoff valves system. Initial investigation findings indicated that the oil fill cap was absent, and both exhaust gases and oil venting from the open fill neck were potential ignition sources.
Further inspection revealed significant fuel leakage into the engine, leading to the accumulation of unburnt diesel fuel. The primary cause of the incident was determined to be improper operation of the engine’s right bank air shutoff valve (air flap). The emergency air flap remained closed, restricting adequate airflow to the engine and preventing proper fuel combustion.
As a result, unburnt diesel fuel and excess oil that had leaked past the piston rings accumulated. This accumulation, combined with heat generated from the operational left bank, ignited the fire.
Contributing factors
- The right bank air flap failed to fully engage with its microswitch preventing the activation of a critical alarm that could have alerted personnel to the issue.
- The malfunction of the air shutoff valves during maintenance indicates that existing procedures or verification checks were insufficient to ensure that all components functioned properly before the engine was returned to service.
- The accumulation of unburnt diesel fuel and excessive oil levels suggests that inadequate monitoring or maintenance practices may have failed to detect and address fuel leakage past the piston rings.
- The absence of the oil fill cap may have contributed to the excessive oil levels and leakage, indicating a potential lapse in routine maintenance or post-maintenance inspection procedures.
Lessons learned
- Enhance inspection protocols for air shutoff valves and related alarm systems during routine maintenance to ensure proper functionality and early detection of potential failures.
- Conduct training sessions for personnel on monitoring engine performance, identifying abnormal conditions, and verifying the functionality of critical alarm systems to enhance operational awareness and response readiness.
- Review and update maintenance procedures to include comprehensive checks for potential fuel and oil leaks, especially following maintenance activities to confirm system integrity before returning equipment to service.
- Ensure diesel engine air intake shutdown devices are installed and fully operational in compliance with 30 CFR 250.856.
- Air intake systems should be functionally tested according to manufacturer instructions or prior to use.
- Incorporate requirements into rental generator procurement processes to include documentation of safety device functionality, engine maintenance history, and verification of critical operating functions. This recommendation addresses the contributing factors identified in this alert. Specifically, if an engine has more than one emergency air flap, each must be tested independently during the third-party inspection prior to commissioning, and each should be capable of shutting down the unit independently.