Fargoo - thanks again. I now have a copy of SIL 29 - 100 via Airbus. SIL mentions inspections to be carried out every 20 months for signs of deterioration and if witnessed replacement best before failure occurs (leak). Do you (or other helpful being) know if the inspections take place in conjunction with other maintainance and if there should be a log of same? Assume if airline are attentive then the leak should not occur as inspection should have revealed the problem prior - or am I being too harsh?