We get asked all the time why we "insist" on firesleeving our FWF hoses. Aside from the obvious reason of 'fire/heat' protection, and the extra instulation properties, and occurencelast week drove the point home.
Recieved an email and pics from a long time client---although NOT for this application---asking about potential damage. Apparently during some sort of maintenance procedure, something contacted the positive battery post and the oil pressure hose---unprotected. You can see the burn marks on the braid, and the burned through wires to the liner. Client says it didnt leak, but wanted an option.
1) Dont fly it, or even run the engine until its replaced. Just because it doesnt leak now, doesnt mean that in flight it wont. The braid had been compromised, so in that area the amount of fluid pressure retention is reduced. Eventually more wires would break and a bubble would try and form until pop goes the weazle.
Using some form of non-metallic protection over the braid----standard AS1072 firesleeve, or full silicone outer covering is a great reason to protect the hose. On our integral hoses, we have a conforming HIGH temp Silicone protective cuff that covers the crimp collar area, not only against heat/fire, but from outside occurences like this. (Ever dropped a screwdriver? You get the idea---it only takes a second to create a spark to potentially pinprick the liner and cause a leak.)
So, this isnt the first time this has happened, on wont be the last, but a good time to do a refresser on the little things that seem expensive at the time, but protentially catrastrophe saving in the long run.
Tom
Recieved an email and pics from a long time client---although NOT for this application---asking about potential damage. Apparently during some sort of maintenance procedure, something contacted the positive battery post and the oil pressure hose---unprotected. You can see the burn marks on the braid, and the burned through wires to the liner. Client says it didnt leak, but wanted an option.
1) Dont fly it, or even run the engine until its replaced. Just because it doesnt leak now, doesnt mean that in flight it wont. The braid had been compromised, so in that area the amount of fluid pressure retention is reduced. Eventually more wires would break and a bubble would try and form until pop goes the weazle.
Using some form of non-metallic protection over the braid----standard AS1072 firesleeve, or full silicone outer covering is a great reason to protect the hose. On our integral hoses, we have a conforming HIGH temp Silicone protective cuff that covers the crimp collar area, not only against heat/fire, but from outside occurences like this. (Ever dropped a screwdriver? You get the idea---it only takes a second to create a spark to potentially pinprick the liner and cause a leak.)
So, this isnt the first time this has happened, on wont be the last, but a good time to do a refresser on the little things that seem expensive at the time, but protentially catrastrophe saving in the long run.
Tom
