Air carrier widebody transport experiences excessive heat under cabin floor due to a leak in the air...

Attributes
ACN	153764
Time
Date	199008
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : mlc
State Reference	OK
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude other other
Route In Use	departure other enroute airway : v63
Flight Plan	IFR
Person 1
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 : 165 flight time total : 18000 flight time type : 4000
ASRS Report	153764
Person 2
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical aircraft equipment problem : less severe
Independent Detector	other other : unspecified
Resolutory Action	flight crew : overcame equipment problem other other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

While climbing through 10000' MSL the #1 F/a notified the cockpit of a sudden whistling air nose and intense heat in the rear cabin. All indications were normal in the cockpit. The F/east isolated the #1 pneumatic system and #1 air conditioning pack and went to the cabin. The floor and wall around seat 40A was so hot that the F/east burned his fingertips while investigating. The air noise was still present and a scorching smell was noticed. The F/east reinstated the #1 pneumatic system and air conditioning pack and isolated the #2 systems. This stopped the air noise and after a period of time the heat buildup stopped and began to decrease. The F/east contacted our maintenance personnel and we were advised to return to dfw. We advised ATC of our need to return to dfw and that we needed to dump fuel. Fuel dumping was attempted but the dump system would automatically shut off each time the fuel dump switch was opened. The system acted as if it were sensing a fuel tank level at the minimum dump level. The F/east was finally able to dump only the fuel in the auxiliary tank at a very slow rate. The left wing dump valve remained open after fuel dumping was discontinued. The remainder of the fuel that could not be dumped was burned while holding at buj. A normal landing was made at 403000# gross weight. The following abnormalities were found by maintenance: 1) a leak in the air supply line to the fat cargo heat valve. 2) a faulty low level shutoff switch in #2 fuel tank.

Original NASA ASRS Text

Title: ACR WDB EXPERIENCES EXCESSIVE HEAT UNDER CABIN FLOOR DUE TO A LEAK IN THE AIR SUPPLY TO THE AFT CARGO HEAT VALVE. FLT ATTEMPTS TO DUMP FUEL FOR A RETURN TO DFW, BUT IS THWARTED BY A FAULTY LOW-LEVEL SHUTOFF SWITCH IN THE #2 FUEL TANK.

Narrative: WHILE CLBING THROUGH 10000' MSL THE #1 F/A NOTIFIED THE COCKPIT OF A SUDDEN WHISTLING AIR NOSE AND INTENSE HEAT IN THE REAR CABIN. ALL INDICATIONS WERE NORMAL IN THE COCKPIT. THE F/E ISOLATED THE #1 PNEUMATIC SYS AND #1 AIR CONDITIONING PACK AND WENT TO THE CABIN. THE FLOOR AND WALL AROUND SEAT 40A WAS SO HOT THAT THE F/E BURNED HIS FINGERTIPS WHILE INVESTIGATING. THE AIR NOISE WAS STILL PRESENT AND A SCORCHING SMELL WAS NOTICED. THE F/E REINSTATED THE #1 PNEUMATIC SYS AND AIR CONDITIONING PACK AND ISOLATED THE #2 SYSTEMS. THIS STOPPED THE AIR NOISE AND AFTER A PERIOD OF TIME THE HEAT BUILDUP STOPPED AND BEGAN TO DECREASE. THE F/E CONTACTED OUR MAINT PERSONNEL AND WE WERE ADVISED TO RETURN TO DFW. WE ADVISED ATC OF OUR NEED TO RETURN TO DFW AND THAT WE NEEDED TO DUMP FUEL. FUEL DUMPING WAS ATTEMPTED BUT THE DUMP SYS WOULD AUTOMATICALLY SHUT OFF EACH TIME THE FUEL DUMP SWITCH WAS OPENED. THE SYS ACTED AS IF IT WERE SENSING A FUEL TANK LEVEL AT THE MINIMUM DUMP LEVEL. THE F/E WAS FINALLY ABLE TO DUMP ONLY THE FUEL IN THE AUX TANK AT A VERY SLOW RATE. THE LEFT WING DUMP VALVE REMAINED OPEN AFTER FUEL DUMPING WAS DISCONTINUED. THE REMAINDER OF THE FUEL THAT COULD NOT BE DUMPED WAS BURNED WHILE HOLDING AT BUJ. A NORMAL LNDG WAS MADE AT 403000# GROSS WT. THE FOLLOWING ABNORMALITIES WERE FOUND BY MAINT: 1) A LEAK IN THE AIR SUPPLY LINE TO THE FAT CARGO HEAT VALVE. 2) A FAULTY LOW LEVEL SHUTOFF SWITCH IN #2 FUEL TANK.

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.

Air carrier widebody transport experiences excessive heat under cabin floor due to a leak in the air supply to the aft cargo heat valve. Flight attempts to dump fuel for a return to dfw, but is thwarted by a faulty low-level shutoff switch in the #2 fuel tank.