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aircraft from North America and Australia.
6.5 CRJ Results
The results of the inspection of Bombardier CRJ fanjet aircraft are provided immediately below
followed by the results of the Bombardier turboprop inspection program. Both are summarized at
the conclusion of this AWG report (see section 6.7).
6.5.1 Bonding Jumpers
All bonding jumpers were securely in place with no missing jumpers. No frayed, damaged,
corroded, or disconnected bonding jumpers were found. All jumper measurements were within
limits for electrostatic bonding and were performing their intended function.
6.5.2 Fuel Quantity Indication System (FQIS) Wiring
The fuel quantity transmitter probes and the compensators are variable capacitors that change
capacitance in relation to the amount of fuel in the tank. No chafing, cracking, degradation,
exposed connectors or any wiring deficiencies were found.
6.5.3 Condition of Fuel Pumps, Fuel Lines, and Fittings
A few instances of resistances above production limits were encountered because of the presence
of blue anodizing on the faying surfaces of AN fittings. This nonconductive coating must be
removed and the surface treated for corrosion protection before installation. Presently, Bombardier
6.0 Bombardier Working Group Report (continued)
August 4, 2000 Industry AFFSP Report Page 59
is using fittings with an ion vapor deposit (IVD) coating, which is conductive. Since August 1999,
moreover, bonding measurements are being taken of 100 percent of these connections during
production.
The couplings used on the CRJ are a self-bonding type manufactured by Wiggins, Hydra-flow, or
both. One instance was encountered where the resistance was greater than 20 ohms (the meter’s
limit) and no measurement could be obtained. The coupling was disconnected, and the tubes were
found misaligned. Once realigned and connected, bonding was within limits. The production line
is now monitored for this condition, and bonding jumpers are installed across all Wiggins
couplings to expedite production. No electrostatic issues affecting airworthiness were encountered.
The CRJ routes wires for valves and pumps through aluminum conduits. No damage or chafing of
wire conduits was found during the inspections. Two conduits, with wires, were removed from a
fleet leader, these being a fuel boost pump conduit and a fuel cross-flow shutoff valve (SOV)
conduit. There was nothing to report on the boost pump conduit—no chafing or wire degradation.
Minor chafing was found on the wiring in the cross-flow SOV conduit. After approximately
15,000 hours flight time, the outer insulation jacket of a three-wire bundle was found partially
chafed. It has been decided to conduct a sampling program of these conduits consisting of units of
varying ages to determine how they are wearing over time.
6.5.4 Electrical Bonding
The CRJ service bulletin comprises more than 110 bonding measurements. These included
bonding jumpers (for vent lines and fuel lines to structure) and faying surfaces (pumps, level
sensors, and temperature sensors). While measurements varied, no electrostatic issues affecting
airworthiness were encountered.
The CRJ has three electric boost pumps per aircraft. On one aircraft, one of these pumps had a
higher resistance than the others, possibly due to nonconductive sealant being used in conjunction
with the conductive gasket. Difficulty sealing this gasket has been encountered, and a redesigned
gasket is now used. A service bulletin to inspect for sealant and clean if necessary is scheduled for
release in September 2000. The resistances encountered between these pumps and the aircraft
structure were very low, with approximately 80 percent below 5 milliohms, and no airworthiness
issue was present.
6.5.5 Foreign Object Debris
Two small nuts were found that are thought to be from production. No damage from foreign
objects was found.
6.5.6 General Tank Condition
The general condition of the inspected tanks was excellent. No visible signs of aging, corrosion,
wire degradation, foreign deposits, or damage were found. These tanks are too small to be fully
entered by maintenance personnel, which reduces the likelihood of physical damage.
6.0 Bombardier Working Group Report (continued)
Page 60 Industry AFFSP Report August 4, 2000
6.6 de Havilland Group Results
The results of the inspection of the de Havilland Canada (DHC) Dash 8 turboprop commuter
airliner of Bombardier Aerospace are summarized below.
6.6.1 Electrical Wiring and Bonding Jumpers
Electrical wiring is routed within the fuel tank to support the operation of the auxiliary fuel boost
pump, low fuel level warning, and the pressure relief valve position indication. See section 6.6.2
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