Hydrogen fire on a LH2 transfer line to an aerospace vehicle

A hydrogen fire broke out at the aft end of the orbiter connected to the LH2 onboard tank of a space shuttle.
This happened during the abortion of the launch, occurred due to another cause, the failure to start of one of the three main engines. The leak and fire went unnoticed because the attention of the operators was focussed on the engine problem. The automatic pad’s fire suppression system came on to deal with the fire.

The exact location of the leak and the cause of it are not provided by the source.
From similar events it can be assumed that the leak was highly probably located at the connection between the umbilical transfer line and the onboard tank.
The fact that the fire, which could have caused arm to the crew, went unnoticed speaks for a lack of effective procedure. Nevertheless, the safety system functioned as expected and the fire was suppressed by the automatic fire suppression system installed on the launch platform.

various lauch aborts had already taken place in the previous days, for reasons unrelated to the LH2 systems

DESCRIPTION OF THE GROUND LH2 FUELLING SYSTEM
The liquid hydrogen (LH2) used as a fuel is kept in an 850,000-gallon tank (230 tons of hydrogen) on the northeast corner of the launch pad. The LH2 is transferred from the storage tank in a vacuum-jacketed line that feed into the orbiter and external tank via the tail service masts on the Mobile Launcher Platform.

DESCRIPTION OF THE ONOBARD LH2 TANK
The liquid hydrogen tank in the Space Shuttle's external tank had a capacity of approximately 390,139 gallons or (106 tons of hydrogen).

The automatic fire suppression system detected and extiguished the fire

Several events, one much more recent than this one (see for example HIAD_1223 and HIAD_1225) witness the difficulty to design and to maintain leak-free the complex liquid hydrogen transfer operations from ground to the vehicles, and the need of learning by doing.

What makes this event a special one, is the presence of personnel in the vicinity of the leak. When the launch was aborted, the crew had to leave the vehicle, but the flame was still on. The source report that “If the crew had evacuated at that time, they would have run through the invisible flames. When the crew did finally egress the shuttle, they received a good dousing of water. If the assumption of leak at the umbilical connection is correct, the flame must have been more than 5 m long, which is the distance between the umbilical connection (at 167 feet, 51 m) and the arm for the crew access to the orbiter (147 feet, 45 m).