> >.  All certified aircraft hose assys are pressure
 > > > tested before the shop releases them to the customer.

 marc wiese wrote:
 >
 > I don't think so. Even if the AC says so! It "should be tested" for sure.
 > But don't count on it! Sometimes they don't even clean it out after
 > assembling it! (as if certification meant anything). Been there, seen it.

That depends on if it is or is not used in a "critical application." The
critical application hoses are procured only from manufacturers that are
"current" on the
QPL (qualified products list) for that NSN (National Stock Number). Each part
purchased by the government is assigned a NSN. It may have more than one part
number because each manufacturer has their own part numbering scheme. For
example a hose on a C-130H may have a NSN, say 4730-01-412-2399. This is a
critical application hose with two manufacturers qualified. Say Stratoflex
and Aeroquip. Both manufacturers have submitted samples to government labs
for testing to destruction. Every test that can be performed is performed.
Additional production samples are tested (destroyed) from each lot
manufactured. Tests are observed by a Government rep. This is done for every
contract for this hose. Every hose is pressure tested. Every hose is cleaned
and capped. Every hose has a metal sleeve spot welded on, that lists the
contract number, (the contract number includes the year of the contract for
shelf life items) the CAGE (commercial and Government entity), 00624 for
Aeroquip. And the manufacturers part number. These hoses are made to a number
of military specifications. The basic Mil-H spec is listed first. The QPL is
the last spec on the list with the same number as the basic spec. Two hoses
from the same manufacturer can be identical in construction and hose ends,
and have the same performance. They may have different part numbers. One for
the QPL item and one for the nonQPL item. Otherwise you have to research the
contract number to see if the QPL item was required. See any room for
disaster here?  It's worse than that, but you get the idea. Looking at the
stainless tag on the hose only tells you the government bought it, and maybe
what spec the hose and or the ends, and or the assembly was made to. Not how
good it is. If you don't know your hoses, have them made up new by an
Aeroquip dealer to the MIL-H for whatever you are doing. You can screw almost
any kind of reusable fitting on a MIL-H hose. That don't make it a MIL spec
assembly. If you can assemble the oil lines for your airplane in the garage,
don' t use them. Have them made by Aeroquip with crimped connections and
pressure tested. You should almost be able to pick up the plane by pulling on
one end of that hose. Would the one you found in the surplus pile be OK? How
about the one you found at the flymarket last year?
Lynn E. Hanover

 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.

http://home.earthlink.net/~rotaryeng/            http://www.linux.org