To repair large damaged areas, cut out the damaged sections and twist two
sections of tubing together to create the length needed and glue with RTV.
A
B
A
T WIST
B
A
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B
PULL
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ducting off and replace it. This can be expensive for every periodic
inspection needed on carb heat ducting for example. Resist the
temptation to cinch the clamps up tight. The ducting should be supported by clamps (Adel or MS21919 type) in hot areas and can be
supported with nylon tie-wraps in cabin areas.
If ducting has been damaged by minor abrasion or small holes, it
can be repaired using the appropriate color RTV silicone. Just massage the silicone into the damaged area and let it cure. If you are
careful, you can even make small patches to ducting. For larger damaged sections, the ducting can actually be screwed together, along
the spiral of the wire. Again, I assure the integrity of the bond by gluing it with RTV. However, usual practice is to periodically replace
the ducting when it is worn or damaged. I try to keep lengths of the
standard sizes around for periodic (annual) inspection time, and I
always put new ducting on during engine overhauls and cabin interior replacement.
I hope this discussion of ducting has offered a breath of fresh
air for you and will help you with constructing or maintaining your
aircraft.
Richard Koehler has been an EAA member since 1980. He is an active airframe
and powerplant mechanic with inspection authorization, a commercial pilot
with instrument and multi-engine ratings, and a technical counselor and
flight advisor.