Narrative:

Some months ago; wanting to reduce the load in my already-over-45 pound flight bag; I purchased a pair of black flashlights by cyclops which run on CR123A lithium batteries. The package of two cost $20; and the batteries were included (also cyclops brand). These are led-type flashlights which appear rugged and are very bright; hence; useable for exterior preflight duties. During my last trip I had just finished the walk-around using one of these flashlights. The beam was dimming as I finished the exterior preflight and I assumed the batteries were wearing out; so I turned off the flashlight as I climbed the stairs and returned to the cockpit. In the cockpit; I laid the flashlight in the small (2x7x1 inches deep) compartment just outboard of my right knee (first officer seat) and continued my interior preflight. About 5 minutes later; there were two loud 'bangs' in rapid succession which I determined were coming from the flashlight. These sounded like gunshots (just about that loud) and blew the cap over the on-off switch past my arm and somewhere into the cockpit behind me. The smell of acrid smoke was in the air and I didn't really know if the darned case was going to blow up completely; so I grabbed the flashlight to get it into the back part of the cockpit (no; I didn't lob it into the first class area). The flashlight body was so hot at this point that it burned my hand and fingertips. I moved my flight bag to partially cover the light and pushed it back into the corner under the jumpseat. I called maintenance but didn't quite know what to ask for (in terms of support or tools) to get the hot flashlight with the potential to explode out of the cockpit. I asked for a mechanic with a long pliers or vise-grip. This led to some 'inspired commentary' from the maintenance guy on the frequency; but I convinced him this was necessary and I needed the guy right now! When the mechanic arrived I kept him out of the cockpit and explained the situation -- he replied; 'oh; sounds like battery overheat -- no problem;' and went into the cockpit; and with the pliers; grabbed the light and disappeared out the jetway door. So... The immediate crisis was over. I write all this to let you know that the cyclops brand of flashlight; or the batteries (CR123A; 3.0 volt lithium); also marketed by cyclops may be defective! They sure were in my case. I started thinking about what could have happened if I'd put the light back into my flight case -- would it have been hot enough to start my charts on fire? I don't want to test that.callback conversation with reporter revealed the following information: reporter stated the CR123A batteries used in his 'cyclops' flashlight were not rechargeable and believes they were of the lithium-metal type. The flashlight casing appeared to be made of aluminum and became very warm even as the light intensity was diminishing. The rubber end cap over the 'on-off' switch on the bottom of the light blew off when both batteries exploded. As noted in his report; after both batteries exploded; the flashlight casing became 'very' hot.

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Original NASA ASRS Text

Title: ACR PILOT REPORTS OF HIS 'CYCLOPS' BRAND FLASHLIGHT CONTAINING CR123A LITHIUM BATTERIES EXPLODING WITH TWO LOUD BANGS AND BLOWING THE CAP OFF THE FLASHLIGHT INTO THE AFT SECTION OF THE COCKPIT.

Narrative: SOME MONTHS AGO; WANTING TO REDUCE THE LOAD IN MY ALREADY-OVER-45 LB FLIGHT BAG; I PURCHASED A PAIR OF BLACK FLASHLIGHTS BY CYCLOPS WHICH RUN ON CR123A LITHIUM BATTERIES. THE PACKAGE OF TWO COST $20; AND THE BATTERIES WERE INCLUDED (ALSO CYCLOPS BRAND). THESE ARE LED-TYPE FLASHLIGHTS WHICH APPEAR RUGGED AND ARE VERY BRIGHT; HENCE; USEABLE FOR EXTERIOR PREFLIGHT DUTIES. DURING MY LAST TRIP I HAD JUST FINISHED THE WALK-AROUND USING ONE OF THESE FLASHLIGHTS. THE BEAM WAS DIMMING AS I FINISHED THE EXTERIOR PREFLIGHT AND I ASSUMED THE BATTERIES WERE WEARING OUT; SO I TURNED OFF THE FLASHLIGHT AS I CLIMBED THE STAIRS AND RETURNED TO THE COCKPIT. IN THE COCKPIT; I LAID THE FLASHLIGHT IN THE SMALL (2X7X1 INCHES DEEP) COMPARTMENT JUST OUTBOARD OF MY RIGHT KNEE (FO SEAT) AND CONTINUED MY INTERIOR PREFLIGHT. ABOUT 5 MINUTES LATER; THERE WERE TWO LOUD 'BANGS' IN RAPID SUCCESSION WHICH I DETERMINED WERE COMING FROM THE FLASHLIGHT. THESE SOUNDED LIKE GUNSHOTS (JUST ABOUT THAT LOUD) AND BLEW THE CAP OVER THE ON-OFF SWITCH PAST MY ARM AND SOMEWHERE INTO THE COCKPIT BEHIND ME. THE SMELL OF ACRID SMOKE WAS IN THE AIR AND I DIDN'T REALLY KNOW IF THE DARNED CASE WAS GOING TO BLOW UP COMPLETELY; SO I GRABBED THE FLASHLIGHT TO GET IT INTO THE BACK PART OF THE COCKPIT (NO; I DIDN'T LOB IT INTO THE FIRST CLASS AREA). THE FLASHLIGHT BODY WAS SO HOT AT THIS POINT THAT IT BURNED MY HAND AND FINGERTIPS. I MOVED MY FLIGHT BAG TO PARTIALLY COVER THE LIGHT AND PUSHED IT BACK INTO THE CORNER UNDER THE JUMPSEAT. I CALLED MAINT BUT DIDN'T QUITE KNOW WHAT TO ASK FOR (IN TERMS OF SUPPORT OR TOOLS) TO GET THE HOT FLASHLIGHT WITH THE POTENTIAL TO EXPLODE OUT OF THE COCKPIT. I ASKED FOR A MECHANIC WITH A LONG PLIERS OR VISE-GRIP. THIS LED TO SOME 'INSPIRED COMMENTARY' FROM THE MAINTENANCE GUY ON THE FREQUENCY; BUT I CONVINCED HIM THIS WAS NECESSARY AND I NEEDED THE GUY RIGHT NOW! WHEN THE MECHANIC ARRIVED I KEPT HIM OUT OF THE COCKPIT AND EXPLAINED THE SITUATION -- HE REPLIED; 'OH; SOUNDS LIKE BATTERY OVERHEAT -- NO PROBLEM;' AND WENT INTO THE COCKPIT; AND WITH THE PLIERS; GRABBED THE LIGHT AND DISAPPEARED OUT THE JETWAY DOOR. SO... THE IMMEDIATE CRISIS WAS OVER. I WRITE ALL THIS TO LET YOU KNOW THAT THE CYCLOPS BRAND OF FLASHLIGHT; OR THE BATTERIES (CR123A; 3.0 VOLT LITHIUM); ALSO MARKETED BY CYCLOPS MAY BE DEFECTIVE! THEY SURE WERE IN MY CASE. I STARTED THINKING ABOUT WHAT COULD HAVE HAPPENED IF I'D PUT THE LIGHT BACK INTO MY FLIGHT CASE -- WOULD IT HAVE BEEN HOT ENOUGH TO START MY CHARTS ON FIRE? I DON'T WANT TO TEST THAT.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE CR123A BATTERIES USED IN HIS 'CYCLOPS' FLASHLIGHT WERE NOT RECHARGEABLE AND BELIEVES THEY WERE OF THE LITHIUM-METAL TYPE. THE FLASHLIGHT CASING APPEARED TO BE MADE OF ALUMINUM AND BECAME VERY WARM EVEN AS THE LIGHT INTENSITY WAS DIMINISHING. THE RUBBER END CAP OVER THE 'ON-OFF' SWITCH ON THE BOTTOM OF THE LIGHT BLEW OFF WHEN BOTH BATTERIES EXPLODED. AS NOTED IN HIS REPORT; AFTER BOTH BATTERIES EXPLODED; THE FLASHLIGHT CASING BECAME 'VERY' HOT.

Data retrieved from NASA's ASRS site as of May 2009 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.