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Found a 1978 service bulletin that changed how I test fuel pumps
I was digging through old records on a 727 from the 80s and stumbled across a Boeing service bulletin from March 1978. Turns out the recommended test pressure for those old fuel boost pumps was 15 psi, not the 20 psi my shop manual said. Has anyone else found old bulletins that totally contradicted what you were taught?
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benc5320d agoTop Commenter
Guess my shop manual was writing fiction all those years.
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paulw8721d ago
Oh man, that's wild. So the shop manual was just straight up wrong for years? Makes you wonder how many pumps got swapped out for no reason because they read 18 psi and everyone thought they were bad. Did the bulletin say anything about why they dropped it to 15, like was it causing seal failures or something? I've seen old AD notes that changed torque values on engine mounts before but never a pressure spec that different.
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