Emergency descent procedure instituted for aircraft equipment problem in cruise. Diversion to altern...

Attributes
ACN	235596
Time
Date	199303
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : iad
State Reference	VA
Altitude	msl bound lower : 39000 msl bound upper : 39000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	other
Make Model Name	Light Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other other other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : instrument pilot : atp pilot : cfi
Experience	flight time last 90 days : 60 flight time total : 4000 flight time type : 800
ASRS Report	235596
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other other : unspecified
Resolutory Action	flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

In cruise at FL390, the passenger advised us (the flight crew) that the left rear passenger seat was very hot and that smoke was coming out from the side of the seat. I sent the first officer back to investigate and he told me that the wing heat line was overheated and extremely hot and that smoke was forming. I immediately checked the stabilizer/wing heat switch and noticed it was 'off' and had been off for at least 15 mins. We told center that we needed to make a precautionary landing at iad and I made a quick descent to 11000 ft where I knew I could turn off all bleed air if necessary. In the descent, the smoke condition stopped and the wing bleed air line cooled. We landed at iad with no further complications. After landing, maintenance revealed a loose connection in the stabilizer/wing heat line as well as a stuck bleed air line valve upstream, which explained why bleed air was present with the stabilizer/wing switch in the off position. Hot engine bleed air was exiting into the cabin.

Original NASA ASRS Text

Title: EMER DSCNT PROC INSTITUTED FOR ACFT EQUIP PROB IN CRUISE. DIVERSION TO ALTERNATE ARPT.

Narrative: IN CRUISE AT FL390, THE PAX ADVISED US (THE FLC) THAT THE L REAR PAX SEAT WAS VERY HOT AND THAT SMOKE WAS COMING OUT FROM THE SIDE OF THE SEAT. I SENT THE FO BACK TO INVESTIGATE AND HE TOLD ME THAT THE WING HEAT LINE WAS OVERHEATED AND EXTREMELY HOT AND THAT SMOKE WAS FORMING. I IMMEDIATELY CHKED THE STABILIZER/WING HEAT SWITCH AND NOTICED IT WAS 'OFF' AND HAD BEEN OFF FOR AT LEAST 15 MINS. WE TOLD CTR THAT WE NEEDED TO MAKE A PRECAUTIONARY LNDG AT IAD AND I MADE A QUICK DSCNT TO 11000 FT WHERE I KNEW I COULD TURN OFF ALL BLEED AIR IF NECESSARY. IN THE DSCNT, THE SMOKE CONDITION STOPPED AND THE WING BLEED AIR LINE COOLED. WE LANDED AT IAD WITH NO FURTHER COMPLICATIONS. AFTER LNDG, MAINT REVEALED A LOOSE CONNECTION IN THE STABILIZER/WING HEAT LINE AS WELL AS A STUCK BLEED AIR LINE VALVE UPSTREAM, WHICH EXPLAINED WHY BLEED AIR WAS PRESENT WITH THE STABILIZER/WING SWITCH IN THE OFF POS. HOT ENG BLEED AIR WAS EXITING INTO THE CABIN.

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.

Emergency descent procedure instituted for aircraft equipment problem in cruise. Diversion to alternate airport.