Bombardier has begun an audit of the fuel system design on the CRJ700 with supplier Intertechnique following a second emergency airworthiness directive (AD) prompted by fuel leaks on the 70-seat regional jet.
Issued on 16 January, the latest AD imposes operating restrictions until fuel feed lines in the CRJ700's centre wing tank have been inspected for cracks. Almost 70 aircraft in service, plus CRJ700s and CRJ900s in production and awaiting delivery at Bombardier, are affected, says CRJ700/900 product director Jean-Guy Blondin.
Cracks in a boss welded to the main fuel lines running from the left and right main wingtanks to the engines, which pass through the centre tank, are causing fuel to leak into the centre tank, which can quickly overfill. The AD was issued after fuel leaks were reported in four aircraft, Blondin says.
In May last year an emergency AD was issued to address uncommanded fuel transfer between the wing and centre tanks, requiring the installation of redesigned primary fuel ejectors. Following this second AD, Blondin says: "We suspect our design criteria could be improved. We are conducting a complete review of the system to make sure we do not have similar features elsewhere."
The latest operating restrictions limit aircraft range and payload and some long-range routes cannot be flown with full payload or will require an intermediate stop, Blondin says.
As an interim fix, Bombardier is providing replacement fuel lines while it works on a redesign. To ensure it has enough replacement fuel lines, Bombardier is cannibalising the CRJ700/900 production line in Montreal. This could affect deliveries, Blondin says.
Source: Flight International
