A few years back , I was witness to a couple of lengths of flexible fuel hose which had suffered badly from what can only be described as "serious internal haemorrhaging". The worrying part though was that it looked perfectly serviceable from the outside.
With this in mind , I try to stay pretty thorough at PtF renewal time with respect to MPD 1998-019 R1.
In CAP-562 , the CAA recommend dropping a ball bearing approx. 90% of the hose's internal diameter down the pipe to determine any degradation. Sound advice , but how many LAA'ers would have one of them in their 'odds n sods' box.
Small lengths of hose can be removed and visually inspected, but for longer ones in-situ , I have found that getting a split-pin whose head will fit into the I.D. bore without snagging is a good and practical alternative.
Disconnect either end and insert a length of locking wire through , twist it onto the eye of the split-pin and simply pull it through . It works , I've just done it.
Keep the locking wire on its roll and it can be re-used.
I'm certainly not criticising the content of MPD 1998-019 R1 , as it does cover itself by stating that one should ensure bore size is correct and there is adequate free-flow. But it doesn't really emphasise that the worst bit is probably on the hose's inner wall even if the outside looks good.
Apologies in advance if I'm telling granny how to suck eggs here , as I'm fully aware that most LAA'ers are massively knowledgeable, experienced and very 'hands-on'.
Just waiting for someone to say, "yeah ,,done that for years mate"
