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Ed Block
He wrote a letter to AlgoPlus Consulting Ltd. in
Halifax, of which
the contents I quote in full here: "I’m
sorry I couldn’t get back to
you sooner, but things are definitely moving fast. I
wanted to first
congratulate you on being able to appreciate the need
for statistical
analysis in making any meaningful decision (although
obviously limited
by the quality of that data). The problem then is how
to fine-tune the data.
In 1982 I conducted a survey of the major aircraft
manufacturers who
were members of the SAE’s High Temperature
Insulated Wire Committee
(see enclosure #1). This poll provides keen insights
into the evolution
of the design criteria used in the selection of
various wiring insulation
types for the initial construction of these aircraft.
I have since acquired
additional documentation (see enclosure #2) that
amplifies the specific
changes that were made, and obviously only when an
insulation material
was shown to fail. The move from Polyvinyl Chloride
(PVC) used since
jet-powered aircraft, came about due to the
insulation material failing the
FAA’s only prehistoric flammability test (60
degree and no smoke test). It
was followed with the introduction of Poly-X wire in
1969 (early DC-10s and
747s). Its demise came in 1975 when the premature
aging problem was discovered
/admitted. This inherent quality of the insulation
material resulted in radial
-cracking of the insulation, down to the conductor.
Next came Stilan, this
insulation material had a stress-crazing problem
(internal shattering), in
addition to its susceptibility to de-icing fluid and
hydraulic fluid, causing
it to be replaced in 1978. Then came XL-EFTE
(MII-W-22759/34,55 or irradiated
tefzel) and even though it has a 97% smoke optical
density rating (see enclosure
#3) it is still being used today by Boeing in its
747, 767, and 777 lines. This
is particularly alarming when you consider Grumman
Corp. had banned it in 1982
from manned-aerospace flights, due to the
insulation’s toxicity, and NASA’s
subsequent ban in 1983, when they (NASA) determined
this material could explode
in an oxygen-enriched area (e.g. cargo-bay). The
subsequent decisions on the ‘by
default’ use of Kapton go back to 1972, when
arc-tracking was first re-created
by Lockheed Corp. in a laboratory. In 1977, TWA had
asked Boeing not to put this
insulation in anymore of their aircraft, and by 1984,
the FAA’s own internal
documentation showed the problems being experienced
with this material. In 1987,
the military finally banned Kapton from further use,
and in 1988 the FAA
conducted their own experiments on arc-tracking after
receiving a letter from
the Energy and Commerce Committee, based on my
(Block’s) prior briefing to them.
The majority of aircraft built today should hopefully
now have TKT, a composite
construction, that should limit problems in the
future, however political issues
have remained in the equation to this day.
In 1992, I briefed the GAO’s Transportation
Dept. on this problem (see enclosure #4).
They sent letters to the NTSB/FAA asking them if
there was indeed a problem with
the various wire insulations used in commercial
aircraft. Their respective replies
clearly indicated that the problem with wire
insulation was that no one was in a
position to even know if there was one. They relied
totally on the manufacturers
for this expertise. In 1994 I briefed the FAA in
Seattle and Atlantic City, NJ,
on the problems associated with the various types of
degrading wire, that the
Military had experienced. Their answer was indicative
of the aforementioned real
problem (see enclosure #5), that no one had a clue to
the seriousness of the matter.
In 1995, I had the NTSB/FAA form a Joint Task Force
to address this matter more
fully. The results of them once again asking only the
manufacturers for an assessment
of any problems with aircraft wiring was predictable,
there was no problem. The
NTSB replied in February, 1996, the FAA (after
ValuJet 592 and TWA 800), in November
of 1996. I then turned to the White House Commission
and my efforts in supplying
them with documents and video-cassettes finally paid
off (enclosure #6). They
acknowledged that non-structural components e.g. wire
and cable had been overlooked
in regard to safety concerns in February 1997.
On April 10, 1997 I briefed Congress, the FAA, the FBI, the DOTIG, GAO, the NavyDept.,
etc. on the problems with wiring in aircraft. The
result: there was no problem showing
up in the database. I have given this brief history
to underscore the need to
analyze/isolate wire failures by type. Enclosure #7
is therefore the reason I am
writing to you. The last sentence on page 1 is the
root of this matter, that being
that the FAA still maintains that wire is wire. Even
though the FAA contradicts
themselves on this issue at every turn (see enclosure
# 8), they still want to group
wires into one nondescript bundle, that ultimately
gets replaced in the course of the
aircrafts life. Similarly it is supposed, that as
long as they are maintained in the
interim, they will last the life of an aircraft.
The information presented herein proves conclusively
that wire is not wire. The
statement cited in the 3rd paragraph of the NTSBs
response (see enclosure #9) concurs
with this. The statement in the subsequent NTSB
response (enclosure #10) further proves
the distinctions made in wire types.
This brings us to the current need, as evidenced by
the FAAs Non-Structural Systems
Plan announced October 1, 1998. In the Plans Findings
(see enclosure #11) they clearly
state there is currently no systematic process to
identify and address potential
catastrophic failures caused by electrical faults of
wiring systems, aside from accident
investigation associated activities. This declaration
is more telling than it may appear,
beyond the fact that the Plan makes no distinctions
regarding the various wire types nor
their related failure modes. (Enclosure #12) is a
clear case in point, in that this
letter from the NTSB (accident investigation phase
that the FAAs Plan is relying on),
acknowledges that even they cannot correctly
distinguish between various wire types
(Sorry, it is not Kapton, it is XL-EFTE).
Therefore, since the FAA admits to allowing the
manufacturers to choose the wire types
for their aircraft, and they do not then call for any
comprehensive flammability and
smoke tests (like they do on seat-covers) to prove
they are safe, and since the FAA
says there is currently no systematic process to
address potential catastrophic wire
failures in advance, (clearly the NTSB is obviously
not up to the task either, other
than relying on those same manufacturers the FAA
originally relied on, via the party
system), and in that the FAA is not alerting the
pilots of Kapton wired aircraft to not
reset circuit-breakers since wire is wire, something
needs to be done.
I would like to see the development of a model by
model SDR base, that is linked
specifically by wire type used. I do not know what
this would take, but I would like
your opinion/input. This would provide a more
fine-tuned look at the problems related
to the wiring we are facing, and dispel the notion
that wire is replaced, maintained,
or that wire is wire. Also, when the wire
manufacturer announced Poly-X wire they said
perhaps it could last 60,000 hours. TWA 800, wired
with Poly-X had 93,303. That is the
next hurdle, establishing a realistic life-expectancy
for wire.
Please let me know of any questions or comments.
Sincerely,
Edward
Block
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