Event
- Event ID
- 331
- Quality
- Description
An unscheduled venting of a stage LH2 tank occurred, creating a hazardous condition for personnel and creating a potential explosion/ fire.
- Event Initiating system
- Classification of the physical effects
- Unignited Hydrogen Release
- Nature of the consequences
- leak no ignition
- Macro-region
- North America
- Country
- United States
- Date
- -
- Component involved
- pressure regulator
- Failure mode
- leak, no ignition
- Initiating cause
- wrong operation
- Root CAUSE analysis
The flexible hose from a gas bottle was left connected to the LH2 vent valve control valve. Seepage through the regulator probably occurred and the regulator control or gas bottle control valve may have been left inadvertently open.
ROOT CAUSE was a mistake in the execution of the pre-launch procedures, possibly enabled by lack of checks.
- Root causes
- Date entry in HIAD
- 30/10/2025
Facility
- Application
- Non-road vehicles
- Sub-application
- Aerospace
- Hydrogen supply chain stage
- All components affected
control valve or regulator
- Process temperature range [C]
- cryogenic temperature (below -50°C)
- Location type
- Unknown
- Location
- countryside or desert
- Operational condition
- UNKNOWN
- Pre-event occurrences
The event occurred during a pre-launch checkout
Emergency & Consequences
- Number of fatalities
- 0
- Number of injured persons
- 0
In-depth data
- Release type
- gas
- Involved substances (% vol)
- H2 100%
- Probable IGNITION SOURCE
References
- Sources categories
- ORDIN
- Reference & weblink
Mishap no 40 in
P. L. Ordin, Review of hydrogen accidents and incidents in NASA operations, 1974, NASA TM X-71565
https://ntrs.nasa.gov/citations/19740020344Hankinson and Lowesmith, Qualitative Risk Assessment of Hydrogen Liquefaction, Storage and Transportation, FCH JU project IDEALHY, Deliverable 3.10 (2013)
confidential
(accessed October 2025)Lowesmith et al., Safety issues of the liquefaction, storage and transportation of liquid hydrogen: An analysis of incidents and HAZIDS, Int. J. Hydrogen energy (2014) https://doi.org/10.1016/j.ijhydene.2014.08.002
