Glasflügel 304 eS FES lithium battery fire at touchdown; cause undetermined

During a normal touchdown at Parham, the forward FES lithium polymer battery of a Glasflügel 304 eS ignited from electrical arcing. Smoke entered the cockpit on rollout; the pilot completed the landing and exited safely. The dislodged battery cover let an external fire develop, extinguished by foam after CO2 failed. Substantial damage to the FES battery box and surrounding fuselage; pilot uninjured. The cause of the arcing could not be determined. This was the second of three known FES battery fires; three safety recommendations followed for mandatory fire warning systems on FES-equipped sailplanes.

1. Aerotow landing: After an aerotow launch, extended ridge soaring with a brief motor run during a rain shower, the pilot returned for a normal circuit and smooth touchdown on the grass runway.
2. Battery ignites on touchdown: At touchdown, an electrical arcing event in the forward FES lithium battery caused it to ignite; the battery compartment cover fractured upward from inside and became dislodged.
3. Smoke enters cockpit: During the landing roll the burning battery produced smoke and fumes that moved forward into the cockpit; the pilot noticed a burning smell and visible smoke. No FCU warnings were recalled.
4. Pilot evacuates glider: The pilot completed the landing roll then vacated the cockpit normally without injury upon recognizing the smoke and fire.
5. External fire develops: After the pilot exited, the missing compartment cover let flames emerge from the forward battery bay, causing extensive fire damage to the fuselage battery box and surrounding structure.
6. Firefighting with foam: The airfield fire crew first attempted a CO2 extinguisher without success, then successfully extinguished the fire by applying aqueous film-forming foam into the FES battery compartment.
7. Fire damage; safety recommendations: The pilot was uninjured; the fire caused substantial damage to the forward battery, compartment, and nearby structure, the second of three known FES battery fires at the time.