Dear all, though you might be interested in the
following findings of a Neico build Lancair. Fortunately, it is not my
aircraft, but another which came in for a tyre change. The work shop asked
if I could share the info with the forum and ascertain if anyone has had a
similar (unfortunate) experience or heard of such an
occurence.
During an unscheduled tyre and tube change, it was discovered that
fuel was dripping out of the R/H wing at the wing attach point . Initially a
faulty drain was suspected but further investigation found the fuel to be
weeping out of the leading edge rib past proseal which has been used to seal
around an electrical wiring conduit. So the fuel was drained from the fuel
tanks and the wiring removed. As removal took place it was noticed that a
substantial amount of fuel was sloshing around in the leading edge, so a
hole was cut in the inboard rib to investigate. Approximately 7 litres of
fuel drained out of the leaking edge.
We suspect the fuel got into the leading edge by passing through some
defective part of the integral fuel tank, through the skin or spar and into
the leading edge.
The reason the defect was not discovered until now was that the
leading edge is almost completely sealed apart from the conduit, which
allows the wires for the strobe light to pass through. Upon drilling the
hole in the leading edge and draining the fuel we inserted a optical fibre
scope for inspection, the result was inconclusive. We also inserted the
probe into the fuel tanks (both inboard and out board and found some signs
that look like tears starting to form in the fibres and defective resin. But
until the wing is cut open it may be impossible to determine if these were
actual defects or just darken spots in the layup of the spar. Several of our
engineers and trained technicians from the Australian NDT services all
viewed the possible defects in the wing with optical fibre scope.
Our engineers have expressed concerns for this type of design and in
particular the previous history of AD/Lancair/2.this particular aircraft
appears to be a Neico build not an Avtex.
- Because
this aircraft has had a sloshing compound in the R/H wing at least three
times over the years.
- Because
there are no inspection panels in the leading edge
- Because
the leading edge is totally sealed, apart from the electrical conduit it was
only a matter of time before the fuel level in the wing made it up to the
strobe light and possibly an explosion with the right fuel air mixture. The
only other way in which this may have been discovered is if fuel was running
out of the conduit, which finishes up near the cockpit.
- The fuel
has been sitting in the leading edge for an unknown time- what effect does
this have on the resins, fibres and honeycomb, already there are small
delaminations appearing under the paint and inside the fuel tank.
- The
imbalance fuel effect on control during high wing loadings/slow speeds. We
estimate that the amount of fuel could have doubled before any signs may
have been evident.
Aircraft history:
Date
17.1.1994…… Statement of Compliance.
17.1.1994…….C of A carried out by Angus Aviation
7.12.1994…….AD/Lancair /Z carried out by Go-Air Products PTY LTD with
nil defects found.
30.9.1997…….RH Wing Re Sealed with slushing compound by Aquila
Aviation PTY LTD Job no
6896
12.5.1998…….RH Wing Fuel pickup replaced and RH wing resealed with
slushing compound, RH wing fuel line section replaced by Aquia PTY LTD job
no 7148
Nil other Log book entries regarding RH fuel tank.
12.10.2004 Fuel leak observed from RH wing. Investigation found fuel
in leading edge fwd of main wing spar (approx 8 litres) same cavity for electrical wires
from Nav and strobe
lights.
Unable at this stage to determine how fuel getting from wet wing
behind main spar, to forward of main spar due unable to access area forward
of main spar
The AD carried out in 1994 was for avtex
manufactured aircraft (unsure if the wings were assembled at their plant in
Ballina Australia then sent out to builders ). Apparently the initial
"sloshing" process was found to be faulty and wings were required to be
re-sloshed.
--
Gerard O Connell
Melbourne,
Australia
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