Flight Crew Air Transport Pilot (ATP)
Confusion
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
General Maintenance Action; General Flight Cancelled / Delayed
Aircraft
With battery in the override position; APU door open; APU not running. Noticed white smoke followed by flames coming out of the [APU] tail pipe. APU fire bottle was discharged; did not extinguish flames. Fire Dept. shot dry chemicals followed by foam to extinguish flames. No fire warning in cockpit at any time.
Reporter stated the Gulfstream G-200 (Astra Galaxy) had been totally dark (no electrical power) for 20-30 minutes. They were waiting in the cockpit for fueling to finish because they are not allowed to start the APU during fueling operations. Fueler saw bright puffs of white smoke coming out from the APU tailpipe that erupted into flames. Later; after the Fire Department applied Dry Chemicals and foam to extinguish the fire; Maintenance removed the Honeywell APU which was immediately sent back to Honeywell for assessment before company mechanics could determine cause for the tailpipe fire. Since then; he has not heard any information from Honeywell regarding the incident.  Reporter stated this was not the first time an APU tailpipe fire has occurred on company G-200 aircraft. His air carrier has since developed a QRH APU Tailpipe Fire Check procedure. The APU tailpipe exits at the end of the aircraft's fuselage; not underneath or on top.
Captain reported he was informed by a Ground Fueler during fueling operations that white smoke followed by flames were coming out of the APU tail pipe on their Gulfstream G-200 (Astra Galaxy) aircraft. The APU door was open; but the APU was not running. No Fire Warning in cockpit. Discharge of APU fire bottle did not extinguish flames.