blocked vents
First post on R&N. Son of RB-211 chief engineer. Suspect spotter, but not stupid.
Blocked vents are a problem in cars and motorbikes. First hand experience. However, a boat experience leads me to suggest that evidence of this would have been immediately available to the AAIB.
Brand new boat fitted with a £30 freshwater distibution pump. Unfortunately the tank breather had tape over it. When we ran out of water I went to refill the tanks. Wouldn't take more than a few gallons into at least 40 gallons capacity. Investigate. Two stainless tanks almost completely crushed. Amazing what a cheap pump can achieve. Bet a 777 pump can get closer to 0 atm than a cheap ITT pump.
The tank structure is unlikely to to have been designed to cope with 'negative' pressure, and would display obvious signs of such.