Loss of equipment cooling causes a chain reaction.

Attributes
ACN	278111
Time
Date	199407
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : msy airport : iah
State Reference	LA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu tower : lax
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 130 flight time total : 14000 flight time type : 50
ASRS Report	278111
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
Experience	flight time last 90 days : 180 flight time total : 12000 flight time type : 1800
ASRS Report	278110
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : declared emergency
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

At cruise altitude atl-iah we got equipment cooling light, went to alternate and tried several times back to normal but got light back, returned to alternate and kept it there. Mins later got dual dc fail light on IRS. Called maintenance control. As we were talking to maintenance control, battery bus showed negative and the battery was discharging. Generators were normal. Anti-skid light came on. We asked maintenance if we should pull battery charger circuit breaker. They said 'yes,' we pulled it. Then we lost N1 and egt's, (both engines). As we were talking, we lost communication #2. WX at msy and WX between us and lft, we decided to continue to iah. We then lost captain's ADI and HSI. Switched his to #2. Tried to switch attitude but lost autoplt. We went back to normal to keep autoplt. We went to flight manual to see what we had or had lost. We then got reverser lights, red gear lights and elevator feel light. We tried to call flight attendants but the call button and PA didn't work. We declared emergency. I flew on autoplt to 2000 ft and then hand flew it. On long final I went back in cabin to verify gear lights. I made normal landing. As we taxied off runway, we smelled smoke. Captain had me get out of my seat and open cabin door since the switch didn't work. We saw thick smoke in cabin. Captain gave order to 'easy vector' out L1, L2 and R2. Nobody was hurt. The smoke was due to packs overheating.

Original NASA ASRS Text

Title: LOSS OF EQUIP COOLING CAUSES A CHAIN REACTION.

Narrative: AT CRUISE ALT ATL-IAH WE GOT EQUIP COOLING LIGHT, WENT TO ALTERNATE AND TRIED SEVERAL TIMES BACK TO NORMAL BUT GOT LIGHT BACK, RETURNED TO ALTERNATE AND KEPT IT THERE. MINS LATER GOT DUAL DC FAIL LIGHT ON IRS. CALLED MAINT CTL. AS WE WERE TALKING TO MAINT CTL, BATTERY BUS SHOWED NEGATIVE AND THE BATTERY WAS DISCHARGING. GENERATORS WERE NORMAL. ANTI-SKID LIGHT CAME ON. WE ASKED MAINT IF WE SHOULD PULL BATTERY CHARGER CIRCUIT BREAKER. THEY SAID 'YES,' WE PULLED IT. THEN WE LOST N1 AND EGT'S, (BOTH ENGS). AS WE WERE TALKING, WE LOST COM #2. WX AT MSY AND WX BTWN US AND LFT, WE DECIDED TO CONTINUE TO IAH. WE THEN LOST CAPT'S ADI AND HSI. SWITCHED HIS TO #2. TRIED TO SWITCH ATTITUDE BUT LOST AUTOPLT. WE WENT BACK TO NORMAL TO KEEP AUTOPLT. WE WENT TO FLT MANUAL TO SEE WHAT WE HAD OR HAD LOST. WE THEN GOT REVERSER LIGHTS, RED GEAR LIGHTS AND ELEVATOR FEEL LIGHT. WE TRIED TO CALL FLT ATTENDANTS BUT THE CALL BUTTON AND PA DIDN'T WORK. WE DECLARED EMER. I FLEW ON AUTOPLT TO 2000 FT AND THEN HAND FLEW IT. ON LONG FINAL I WENT BACK IN CABIN TO VERIFY GEAR LIGHTS. I MADE NORMAL LNDG. AS WE TAXIED OFF RWY, WE SMELLED SMOKE. CAPT HAD ME GET OUT OF MY SEAT AND OPEN CABIN DOOR SINCE THE SWITCH DIDN'T WORK. WE SAW THICK SMOKE IN CABIN. CAPT GAVE ORDER TO 'EASY VECTOR' OUT L1, L2 AND R2. NOBODY WAS HURT. THE SMOKE WAS DUE TO PACKS OVERHEATING.

Data retrieved from NASA's ASRS site as of July 2007 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.