Narrative:

I have a concern about the center fuel tank access door on the B737-700; 800 series aircraft. This particular access door is located above the air conditioning pack like all generation B737S. The older B737S require the center tank access door to be sealed with a fuel tank sealant in order to act as a secondary seal; however; the newer 700 and 800 series do not require a secondary seal. Although the access door on the 700 and 800 series has a different part number than the older B737; the fact that if the door develops a leak with an extremely hot air conditioning pack located just below; there is a high probability that a fire or explosion could occur. In the wake of all the new measures currently in force to make fuel tank safety a priority; the omission of a secondary seal or mylar seal at this critical non-vented area is in my opinion an accident waiting to happen. I would appreciate your assistance in this matter in providing some form of background if this is in fact a correct procedure or if it had just been overlooked and the concern I have is justifiable.callback conversation with reporter revealed the following information: the reporter believes this is a safety of flight item. This lack of a secondary seal also applies to the B737-700 and 900 models and was missing from the maintenance manual tank entry procedure. The reporter believes that while the tank access door is a different part number; the internal seal is still mounted in the door the same as the early B737 aircraft. The concern of the reporter is the non-vented area where a fuel leak or seep on hot engine pneumatic ducts and pack equipment could be catastrophic.

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Original NASA ASRS Text

Title: A DIRECTOR OF QUALITY CONTROL RPTS CONCERN REGARDING A LACK OF SECONDARY SEAL FOR THE CENTER FUEL TANK ACCESS DOOR; WHICH IS LOCATED ABOVE THE LEFT PACK ON THE B737-800. THE EXTERIOR SECONDARY SEAL HAS BEEN ELIMINATED FROM THE MAINT MANUAL.

Narrative: I HAVE A CONCERN ABOUT THE CENTER FUEL TANK ACCESS DOOR ON THE B737-700; 800 SERIES ACFT. THIS PARTICULAR ACCESS DOOR IS LOCATED ABOVE THE AIR CONDITIONING PACK LIKE ALL GENERATION B737S. THE OLDER B737S REQUIRE THE CENTER TANK ACCESS DOOR TO BE SEALED WITH A FUEL TANK SEALANT IN ORDER TO ACT AS A SECONDARY SEAL; HOWEVER; THE NEWER 700 AND 800 SERIES DO NOT REQUIRE A SECONDARY SEAL. ALTHOUGH THE ACCESS DOOR ON THE 700 AND 800 SERIES HAS A DIFFERENT PART NUMBER THAN THE OLDER B737; THE FACT THAT IF THE DOOR DEVELOPS A LEAK WITH AN EXTREMELY HOT AIR CONDITIONING PACK LOCATED JUST BELOW; THERE IS A HIGH PROBABILITY THAT A FIRE OR EXPLOSION COULD OCCUR. IN THE WAKE OF ALL THE NEW MEASURES CURRENTLY IN FORCE TO MAKE FUEL TANK SAFETY A PRIORITY; THE OMISSION OF A SECONDARY SEAL OR MYLAR SEAL AT THIS CRITICAL NON-VENTED AREA IS IN MY OPINION AN ACCIDENT WAITING TO HAPPEN. I WOULD APPRECIATE YOUR ASSISTANCE IN THIS MATTER IN PROVIDING SOME FORM OF BACKGROUND IF THIS IS IN FACT A CORRECT PROC OR IF IT HAD JUST BEEN OVERLOOKED AND THE CONCERN I HAVE IS JUSTIFIABLE.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR BELIEVES THIS IS A SAFETY OF FLT ITEM. THIS LACK OF A SECONDARY SEAL ALSO APPLIES TO THE B737-700 AND 900 MODELS AND WAS MISSING FROM THE MAINT MANUAL TANK ENTRY PROC. THE RPTR BELIEVES THAT WHILE THE TANK ACCESS DOOR IS A DIFFERENT PART NUMBER; THE INTERNAL SEAL IS STILL MOUNTED IN THE DOOR THE SAME AS THE EARLY B737 ACFT. THE CONCERN OF THE RPTR IS THE NON-VENTED AREA WHERE A FUEL LEAK OR SEEP ON HOT ENG PNEUMATIC DUCTS AND PACK EQUIP COULD BE CATASTROPHIC.

Data retrieved from NASA's ASRS site as of January 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.