False fire warning traced to a bleed air leak on #2 engine.

Attributes
ACN	309606
Time
Date	199507
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zoa
State Reference	CA
Altitude	msl bound lower : 37000 msl bound upper : 37000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zoa artcc : zau
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 240 flight time total : 5000 flight time type : 250
ASRS Report	309606
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa other other : unspecified
Resolutory Action	flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

#4 aft cargo smoke detector and master warning light flashed on and off momentarily 2 times, and on at least 1 occasion the #2 engine 'a' loop fire detector also flashed. Maintenance control was called and they indicated a probable bleed air leak. The #2 engine bleed air was turned off per maintenance control. No further indication occurred. All detection circuitry tested normally during and after the indications ceased. All emergency and abnormal procedures were reviewed. Lead flight attendant was advised. Associated cargo temperature indication showed normal at 65 degrees F and we took it lower when we selected a lower temperature. Logbook write-ups the days prior indicated a temperature difference in the #2 pneumatic manifold. For this reason I believe maintenance control was correct.

Original NASA ASRS Text

Title: FALSE FIRE WARNING TRACED TO A BLEED AIR LEAK ON #2 ENG.

Narrative: #4 AFT CARGO SMOKE DETECTOR AND MASTER WARNING LIGHT FLASHED ON AND OFF MOMENTARILY 2 TIMES, AND ON AT LEAST 1 OCCASION THE #2 ENG 'A' LOOP FIRE DETECTOR ALSO FLASHED. MAINT CTL WAS CALLED AND THEY INDICATED A PROBABLE BLEED AIR LEAK. THE #2 ENG BLEED AIR WAS TURNED OFF PER MAINT CTL. NO FURTHER INDICATION OCCURRED. ALL DETECTION CIRCUITRY TESTED NORMALLY DURING AND AFTER THE INDICATIONS CEASED. ALL EMER AND ABNORMAL PROCS WERE REVIEWED. LEAD FLT ATTENDANT WAS ADVISED. ASSOCIATED CARGO TEMP INDICATION SHOWED NORMAL AT 65 DEGS F AND WE TOOK IT LOWER WHEN WE SELECTED A LOWER TEMP. LOGBOOK WRITE-UPS THE DAYS PRIOR INDICATED A TEMP DIFFERENCE IN THE #2 PNEUMATIC MANIFOLD. FOR THIS REASON I BELIEVE MAINT CTL WAS CORRECT.

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.