All Falcon 7Xs now cleared to fly again

 - July 26, 2011, 5:10 AM

Practically all Falcon 7Xs are flying again, following the EASA’s re-authorizing flights for the entire fleet on July 7, three weeks after giving the majority of the fleet the green light to return to service. The FAA followed suit and released an equivalent alternative method of compliance (Amoc) on July 8. As of July 19, only three 7Xs were still on the ground, for reasons unrelated to the pitch trim issue, according to Dassault. The flight envelope will remain restricted until September.

“Technically, the issue is over,” Olivier Villa, Dassault’s senior v-p for civil aircraft, told AIN. One of the three aircraft that is not flying again yet is in China, where local authorities have delayed the process, Villa said. The other two are undergoing unrelated scheduled maintenance, he explained.

Dassault has found a solution for the horizontal stabilizer electronic control unit (HSECU) part number -04. According to the EASA’s latest airworthiness directive (AD), operators can have their HSECU verified by Rockwell Collins. Some units, however, do have a production defect. In the event the unit does not pass the verification test, the operator can have the HSECU replaced by a new one developed by Dassault, part number -05.

In the June 16 AD, the EASA allowed those Falcon 7Xs equipped with HSECU part number -02 (about 80 percent of the fleet, according to Dassault) to resume flight operations.

As for the flight envelope, all Falcon 7Xs remain subject to the limitations Dassault defined in June. At altitude, Mmo is limited to Mach 0.85 instead of Mach 0.9. Lower down, airspeed is limited to 320 knots instead of 370 knots. There is no limitation in weight or cg.

Dassault engineers are finalizing a software modification that will allow it to restore the full flight envelope. The change will be implemented on the aircraft beginning in September. Villa does not expect any difficulty in obtaining EASA approval for the modification.

He also insists that Dassault’s engineers ruled out a malfunction of the fly-by-wire control system be before ferry flights were allowed. Villa added that Falcon 7X production was suspended for some time. Nevertheless, he still hopes that this will have no impact on the number of aircraft delivered this year.

The runaway pitch trim incident that sparked the grounding took place aboard a Falcon 7X approaching Kuala Lumpur, Malaysia, on May 25. According to a European Falcon 7X operator, the incident aircraft pitched up by 36 degrees and climbed from 12,000 feet to 23,000 feet before the crew regained control. Dassault asked the EASA for a grounding, which took effect on May 26. Ferry flights were allowed starting four days later.

Dassault has endeavored to keep operators in the loop, arranging two to three dedicated electronic forums per week and making replacement aircraft and flights available to customers who requested them.