2" flexible ducting (orange) approved for "negative pressure applications"?

[Philster2001]

Hi, I'm trying to source 2" (51mm) flexible (orange) ducting suitable for use in negative pressure applications, such as the hose which connects between the air intake and the carbies on my Rotax 912A. I have an AD which says I can't use the "Aeroduct SCAT" hoses because they are not suitable for negative pressure applications.

 

Thanks in anticipation, Phil

[Thruster88]

SCAT duct is the one to for induction systems. It has the wire inside exposed. It is used on certified aircraft, cessna beech etc. 

[KRviator]

SCAT is (usually) good depending on exact type. SCEET is bad. That's the one that has a lining in it to reduce turbulence, however, this lining can come adrift when used in negative pressure situations, such as induction tubing. Some SCAT hoses can also have the outer lining deteriorate between the wire helix and ingest that too, so it pays to keep an eye on it if its' used as part of your induction system.

Here's a good writeup from FSA in years gone by, incidentally discussing a Gazelle. I remembered it, but CASA's ruined the FSA website, so had to grab it from Wayback... The Wrong Part