<< >> NASA ASRS Report 278957, August 1994

APU fire warning.

Attributes
ACN	278957
Time
Date	199408
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : cmh
State Reference	OH
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air taxi
Make Model Name	Falcon 20FJF/20C/20D/20E/20F
Operating Under FAR Part	Part 135
Navigation In Use	Other Other
Flight Phase	ground : preflight
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 100 flight time total : 13000 flight time type : 4400
ASRS Report	278957
Person 2
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 3500 flight time type : 100
ASRS Report	279636
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	flight crew : overcame equipment problem other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Shortly after starting the APU to perform preflight check, fire warning for APU came on. APU was shutdown and fire extinguisher was discharged. Advised captain, who was not on the airplane at the time. A mechanic checked the airplane as per a conversation with the company director of maintenance. No indication of fire could be found and was noted in the maintenance log. In a conversation with the captain, company director of operations and director of maintenance it was decided to continue the trip with provisions of aircraft MEL. APU was placarded and was not used for the remainder of the flight to the home base for maintenance. Supplemental information from acn 279626: he most likely, accidentally engaged the fire test on the APU. This has happened on other occasions with pilots and maintenance unfamiliar with the APU control panel. There was no sign of a fire or any abnormality. The fire bottle showed pressure and was not discharged. The reason being the APU RPM's must spool down below 5 percent before the extinguisher switch will fire the bottle. Being the fire extinguisher arming switch was activated, by mr. X earlier, when we pushed the fire test button, the extinguisher switch was accidently pushed and the fire bottle was discharged at that time. The fire test button and extinguisher button are not even a thumbs width away from each other. So both buttons unintentionally were pushed simultaneously.

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Original NASA ASRS Text

Title: APU FIRE WARNING.

Narrative: SHORTLY AFTER STARTING THE APU TO PERFORM PREFLT CHK, FIRE WARNING FOR APU CAME ON. APU WAS SHUTDOWN AND FIRE EXTINGUISHER WAS DISCHARGED. ADVISED CAPT, WHO WAS NOT ON THE AIRPLANE AT THE TIME. A MECH CHKED THE AIRPLANE AS PER A CONVERSATION WITH THE COMPANY DIRECTOR OF MAINT. NO INDICATION OF FIRE COULD BE FOUND AND WAS NOTED IN THE MAINT LOG. IN A CONVERSATION WITH THE CAPT, COMPANY DIRECTOR OF OPS AND DIRECTOR OF MAINT IT WAS DECIDED TO CONTINUE THE TRIP WITH PROVISIONS OF ACFT MEL. APU WAS PLACARDED AND WAS NOT USED FOR THE REMAINDER OF THE FLT TO THE HOME BASE FOR MAINT. SUPPLEMENTAL INFO FROM ACN 279626: HE MOST LIKELY, ACCIDENTALLY ENGAGED THE FIRE TEST ON THE APU. THIS HAS HAPPENED ON OTHER OCCASIONS WITH PLTS AND MAINT UNFAMILIAR WITH THE APU CTL PANEL. THERE WAS NO SIGN OF A FIRE OR ANY ABNORMALITY. THE FIRE BOTTLE SHOWED PRESSURE AND WAS NOT DISCHARGED. THE REASON BEING THE APU RPM'S MUST SPOOL DOWN BELOW 5 PERCENT BEFORE THE EXTINGUISHER SWITCH WILL FIRE THE BOTTLE. BEING THE FIRE EXTINGUISHER ARMING SWITCH WAS ACTIVATED, BY MR. X EARLIER, WHEN WE PUSHED THE FIRE TEST BUTTON, THE EXTINGUISHER SWITCH WAS ACCIDENTLY PUSHED AND THE FIRE BOTTLE WAS DISCHARGED AT THAT TIME. THE FIRE TEST BUTTON AND EXTINGUISHER BUTTON ARE NOT EVEN A THUMBS WIDTH AWAY FROM EACH OTHER. SO BOTH BUTTONS UNINTENTIONALLY WERE PUSHED SIMULTANEOUSLY.

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.