|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||0601 To 1200|
|Locale Reference||atc facility : rod|
|Altitude||agl bound lower : 0|
agl bound upper : 0
|Operator||common carrier : air carrier|
|Make Model Name||B747-100|
|Operating Under FAR Part||Part 121|
|Navigation In Use||Other|
|Flight Phase||climbout : intermediate altitude|
|Route In Use||enroute : atlantic|
|Function||other personnel other|
|Qualification||other other : other|
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Qualification||pilot : atp|
|Anomaly||aircraft equipment problem : critical|
other anomaly other
|Independent Detector||other other : unspecified|
|Resolutory Action||flight crew : declared emergency|
none taken : detected after the fact
The autoignition temperature (the temperature at which vapors will spontaneously ignite) of jet-a fuel is lower than most people (including professionals) realize. Jet-a autoignition temperature = 410 degrees F. By comparison, gasoline autoignition temperature = 853 degrees F. Jet-a vapors ignite twice as easily as gasoline vapors. I believe most people intuitively think the autoignition temperature is much higher than it really is. This misconception leads to lax and dangerous use of this fuel. The vapor pressure of jet-a is very low, and I believe this leads to the misconception. Basically, it is difficult to generate jet-a vapors, however, once generated, they ignite very easily. I used to fly the B52G. The manual had a warning that appeared whenever fuel xfer operations out of the body tanks were discussed. The warning stated that the tank boost pumps were not to be run with the body tanks empty, otherwise, the fuel tank could explode. This warning was a result of a B52 which blew up on a touch-and-go landing. The cause was traced to a boost pump which ran dry and overheated. I speculate similar problems occurred on a recent airline disaster. I've enclosed msds sheets for jet-a and gasoline which shows physical properties for these fuels. Callback conversation with reporter revealed the following information: the reporter is a former military pilot who has recently taken some hazardous material training that brought the problems of jet fuel back to mind. He has sent this information to no one except the ASRS. He wishes that the ASRS send this on to the NTSB in case no one there has thought of this problem. He wanted to do this anonymously with the aid of the ASRS. The point of the discussion is 'that jet fuel vapors are hard to form but easy to ignite' when compared with gasoline.
Original NASA ASRS Text
Title: A FORMER B52 PLT, CURRENTLY EMPLOYED AS AN ENVIRONMENTAL ENGINEER, WANTS THE ASRS TO INFORM THE NTSB OF THE HAZARDS OF JET FUEL THAT MAY HAVE BEEN OVERLOOKED.
Narrative: THE AUTOIGNITION TEMP (THE TEMP AT WHICH VAPORS WILL SPONTANEOUSLY IGNITE) OF JET-A FUEL IS LOWER THAN MOST PEOPLE (INCLUDING PROFESSIONALS) REALIZE. JET-A AUTOIGNITION TEMP = 410 DEGS F. BY COMPARISON, GASOLINE AUTOIGNITION TEMP = 853 DEGS F. JET-A VAPORS IGNITE TWICE AS EASILY AS GASOLINE VAPORS. I BELIEVE MOST PEOPLE INTUITIVELY THINK THE AUTOIGNITION TEMP IS MUCH HIGHER THAN IT REALLY IS. THIS MISCONCEPTION LEADS TO LAX AND DANGEROUS USE OF THIS FUEL. THE VAPOR PRESSURE OF JET-A IS VERY LOW, AND I BELIEVE THIS LEADS TO THE MISCONCEPTION. BASICALLY, IT IS DIFFICULT TO GENERATE JET-A VAPORS, HOWEVER, ONCE GENERATED, THEY IGNITE VERY EASILY. I USED TO FLY THE B52G. THE MANUAL HAD A WARNING THAT APPEARED WHENEVER FUEL XFER OPS OUT OF THE BODY TANKS WERE DISCUSSED. THE WARNING STATED THAT THE TANK BOOST PUMPS WERE NOT TO BE RUN WITH THE BODY TANKS EMPTY, OTHERWISE, THE FUEL TANK COULD EXPLODE. THIS WARNING WAS A RESULT OF A B52 WHICH BLEW UP ON A TOUCH-AND-GO LNDG. THE CAUSE WAS TRACED TO A BOOST PUMP WHICH RAN DRY AND OVERHEATED. I SPECULATE SIMILAR PROBS OCCURRED ON A RECENT AIRLINE DISASTER. I'VE ENCLOSED MSDS SHEETS FOR JET-A AND GASOLINE WHICH SHOWS PHYSICAL PROPERTIES FOR THESE FUELS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR IS A FORMER MIL PLT WHO HAS RECENTLY TAKEN SOME HAZARDOUS MATERIAL TRAINING THAT BROUGHT THE PROBS OF JET FUEL BACK TO MIND. HE HAS SENT THIS INFO TO NO ONE EXCEPT THE ASRS. HE WISHES THAT THE ASRS SEND THIS ON TO THE NTSB IN CASE NO ONE THERE HAS THOUGHT OF THIS PROB. HE WANTED TO DO THIS ANONYMOUSLY WITH THE AID OF THE ASRS. THE POINT OF THE DISCUSSION IS 'THAT JET FUEL VAPORS ARE HARD TO FORM BUT EASY TO IGNITE' WHEN COMPARED WITH GASOLINE.
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.