Help With Leak Test Results

Hi,

After reading as much as I could find, and assembling the necessary
tools, I have just started a leak testing program on my 1980 LS4.

I verified that my ASI is well sealed by creating sufficent vacuum on
the static input to show 100kt on ASI and observing no appreciable
airspeed decrease after several minutes.

After verifying the ASI, I used it to test my aft static lines. With
all 4 fuselage static ports blocked with tape, I T'd my 60cc syringe
into the static line, connected the assembly to the ASI and then pulled
suffient negative pressure to measure 100kt on the ASI. After clamping
off the syringe line I verified that the clamp worked by noting that I
could no longer change the ASI reading with the syringe, and then
recorded a 37kt ASI reading decrease over a 6 minute period (just over
6kt/minute)

My question is, do I need to start tearing up the seat pan and tracing
this line back into the fuselage, or is a 6kt/minute ASI reading
decrease OK?

One of the fine articles I read give a subjective threshold for
'goodness' but although the article talked about using the ASI as the
mesuring instrument, the stated threshold was "20ft/minute", (I'm
guessing they used the altimeter instead) ;-).

TIA,

Frank