Bombardier has engaged US manufacturer Eaton to work on additional modifications to the CRJ100/200's flap system, even as a newly redesigned system is about to be tabled for certification.
The move comes as the world's largest CRJ100/200 operator, the USA's SkyWest, reveals it has experienced "some challenges and difficulty" in implementing the flap fix currently available.
Last year Canadian and US regulators issued airworthiness directives aimed at mitigating the number of CRJ100/200 stuck flap incidents that have been linked to cold weather operations moisture ingress is considered the primary contributing factor.
Among other measures, the ADs called for operators to clean and lubricate the flexible shafts and install metallic seals in the flexible drive-shafts. If damage or delamination of sealant extends more than 6.3mm (0.25in) from a lockwire hole, a low-temperature torque check on the actuator must be performed prior to further flight.
The US Federal Aviation Administration's directive further required that operators contact the agency or install a serviceable actuator before resuming service if torque test results are not satisfactory. It gave carriers until 3 January to accomplish this portion of the AD.
A solution to address the maintenance action was developed by Bombardier and Eaton. The vast majority of operators of both CRJ100 and CRJ200 aircraft have complied, says Bombardier, which notes that both firms "have allocated significant resources and investment to ensure that changes to the CRJ100/200 flap system are performed in a timely and efficient manner".
However, the Canadian airframer also set about to develop a permanent fix. The company confirms it has "completed testing of a new seal and, very soon, will share the specifics with the certification authorities".
Bombardier expects upgrades to the fleet to begin early this month, but says "the end date is difficult to determine at this time due largely to operators who fly in warmer climates where other priorities may be in place".
Added to this, however, Bombardier has tapped Eaton for additional modifications. The work with Eaton, which is scheduled to begin in February, will further enhance the system's reliability, and is being done "in the spirit of continuous improvement", says Bombardier.
It's a move being welcomed by SkyWest, whose Atlantic Southeast Airlines and SkyWest Airlines units operate nearly 250 of the type.
SkyWest is "complying with the AD and making required changes as noted and specified by Bombardier" but having "some challenges and difficulty in doing that", says SkyWest vice-president of finance and treasurer Michael Kraupp. "The challenge [is] in ensuring that it is a permanent fix and that you don't have failures after that."
He adds that Bombardier is "working on continuous improvement" but realises "they have a challenge here with the recommended solution and they are seeking an even better fix from what they have today".
Bombardier says it recently dispatched a team of technical experts along with Eaton representatives to SkyWest who together have "developed a plan to rectify issues that have surfaced on a relatively small number of aircraft in its fleet".
"As the service requirements contained in the AD have been applied successfully to hundreds of CRJ aircraft, we anticipate the issues at SkyWest will soon be resolved," says Bombardier. "Looking ahead, we've shared with aviation authorities and CRJ operators a plan to further improve the reliability of the flap system and expect to begin making those modifications very soon."