A gulfstream galaxy flight crew declared an emergency and landed as soon as possible following recei...

Attributes
ACN	984436
Time
Date	201112
Local Time Of Day	0601-1200
Place
Locale Reference	BFI.Airport
State Reference	WA
Aircraft 1
Make Model Name	Gulfstream G200 (IAI 1126 Galaxy)
Operating Under FAR Part	Part 91
Flight Phase	Climb
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	DC Generation Indicating and Warning System
Person 1
Function	Captain
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor Flight Crew Instrument
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 13600 Flight Crew Type 220
Person 2
Function	First Officer
Qualification	Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 3750 Flight Crew Type 750
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

While climbing through about 26;000 ft on the way to 40;000 ft a 'battery hot' message appeared on our cas system. The battery temperature indicated 170 degrees and in the red. The checklist had us isolate the battery from the bus so there would be no charging. We monitored the temperature for a few seconds to see if there was a change. There was none. At this point the checklist says if the temperature is above 160 degrees to 'land as soon as possible.' the fear of course is a nicad battery thermal runaway. We had no choice but to declare an emergency as that action would enable us to land as soon as possible in case it was an actual thermal runaway of the battery. We landed approximately 15 minutes later being given priority handling by ATC and making an ILS approach. The battery temperature indicator read 170 degrees all the way to engine shutdown. After landing it was discovered that the battery was cool and the temperature sensor was faulty giving us the maximum reading. My gut feeling was there was not a thermal runaway; but I felt it not prudent on my part to second guess the system and elected to take the safest course of action.

Original NASA ASRS Text

Title: A Gulfstream Galaxy Flight Crew declared an emergency and landed as soon as possible following receipt of a battery overheat warning. Subsequent investigation determined the source was actually a faulty sensor.

Narrative: While climbing through about 26;000 FT on the way to 40;000 FT a 'Battery Hot' message appeared on our CAS system. The battery temperature indicated 170 degrees and in the red. The checklist had us isolate the battery from the bus so there would be no charging. We monitored the temperature for a few seconds to see if there was a change. There was none. At this point the checklist says if the temperature is above 160 degrees to 'Land as soon as Possible.' The fear of course is a NiCad battery thermal runaway. We had no choice but to Declare An Emergency as that action would enable us to land as soon as possible in case it was an actual thermal runaway of the battery. We landed approximately 15 minutes later being given priority handling by ATC and making an ILS approach. The battery temperature indicator read 170 degrees all the way to engine shutdown. After landing it was discovered that the battery was cool and the temperature sensor was faulty giving us the maximum reading. My gut feeling was there was not a thermal runaway; but I felt it not prudent on my part to second guess the system and elected to take the safest course of action.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A gulfstream galaxy flight crew declared an emergency and landed as soon as possible following receipt of a battery overheat warning. Subsequent investigation determined the source was actually a faulty sensor.