This maintenance Hi-Light alerts staff to the risk of partially disbonded fuel tank access door seals
remaining undetected prior to fuel tank access door installation.
An investigation of an in-service fuel leak occurrence on a B737NG aircraft has identified that partial seal disbond can be difficult to detect, even on a section of seal known to be disbonded.
It is recommended to apply firm pressure to the seal with fingertips and attempt to compress the seal over 1-2 inches of seal at a time. If a section of the seal is disbonded, the seal will “caterpillar” up out of access door groove (as shown in illustration above). The aircraft manufacturer is considering adding this procedure to the AMM. Note: AMM Task 28-11-11-900-801 provides instructions for replacing defective fuel tank access door seals on B737NG aircraft and AMM Task 28-11-11-908-00 for fuel tank access panel seal repairs on B737 Classic Series aircraft.
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