Eurocopter has implemented a software change to its health and usage monitoring systems (HUMS) in an effort to return the grounded fleet of oil and gas drilling and exploration industry EC225 to operation.

The European helicopter manufacturer is working with regulators and accident investigators to validate the idea that real-time surveillance of the gearbox on the aircraft is enough to get the helicopters flying again while the company works on a permanent solution.

CEO Lutz Bertling says the interim fix might allow for the rotorcraft to be flying again by the third quarter of this year. The EC225 was grounded by U.K. and Norwegian authorities in October 2012, following the second of two forced landings in the North Sea. The groundings have had a dramatic effect on North Sea helicopter flights, and some operators such as Bristow are only now returning to capacity and normal flight operations.

The two ditchings, one in March 2012 and the second seven months later, were initiated by failures in the bevel gear vertical shaft, a critical component in the main gearbox (MGB) that drives the two lubrication pumps. The ditchings were necessitated when the flight crews were presented with warnings that a falsely indicated that the emergency lubrication system for the MGB had failed, a glitch that has been corrected.

As an interim fix, the company is planning to update the EC225 HUMS—known as M-ARMS (modular aircraft recording monitoring system)—with a capability to monitor gearbox vibration in real-time. With some modifications to the cockpit, the enhanced HUMS will warn pilots immediately if cracks are propagating into the bevel gear shaft. Pilots will be alerted to land within a specific, as yet undecided, period of time. This is a key point being discussed with regulators. According to Bertling, the final fix will involve a new design of the bevel gear shaft.

“We can reproduce the fault at any time; it has been clearly identified,” Bertling said at the company's facilities in Marignane, near Marseille, on April 17. He said the issues with the shaft include “residual stresses from the manufacturing process” and corrosion on the component. The company is sending data from its findings to the authorities as well as to independent experts from the Georgia Technology Research Institute, an organization selected by the helicopter operators to verify the manufacturer's findings.

Officials close to the program told Aviation Week that engineers had purposely cracked eight of the components during bench testing and that one of the gearboxes would now be fitted to aircraft to carry out flight tests to determine whether the cracks propagate the same way in flight. Bertling says he would like to see the fix ready before he leaves at the end of May for his new role as president and COO of Bombardier Transportation. He emphasizes that resolving the matter is a top priority and is one the biggest challenges in Eurocopter's history.

Operators say they are concerned that the aircraft may not return to full capability until next year. According to Bristow, the incidents and the subsequent grounding demonstrated just how important the helicopter has become to the offshore oil and gas industry. Speaking at the company's analyst day on April 10, Mark Duncan, senior vice president for commercial business, said that although the helicopter only represented around 5% of the cost of running oil and gas platforms, the loss of rotorcraft service “affects the other 95%”

“The incident has highlighted the criticality of our service,” Duncan said. “Security of supply [of helicopters] has become more important than the cost.”

While none of Bristow's helicopters were involved in the two incidents, the company, like other North Sea operators, was ordered to ground its fleet. For Bristow, this means 16 of its aircraft remain parked. In the days immediately after the grounding, the company had just two helicopters available to service the platforms.

Six months later, the company is only now returning to full-fleet strength, achieved via the arrival of new S-92s and by repositioning its international fleet, as well as by pulling old Aerospatiale AS332Ls, known as Bristow Tigers, out of retirement.

Despite the grounding, the aircraft in both its military and civil variants is in full production, and Eurocopter plans to ramp-up output in 2014 with an extension to the Marignane assembly line.