AgustaWestland, March 03, 2015 - AgustaWestland has successfully demonstrated to the Italian Airworthiness Authority – Ente Nazionale Aviation Civile (ENAC) a 60+ minutes loss of oil or “run dry” capability for the AW139 main gearbox (MGB).
The AW139 will be the first helicopter ever to enter service with such a capability, which is 30 minutes more than any other currently certified competing helicopter.
Following 63 minutes of testing, the AW139 main gearbox was disassembled and the components inspected. Although some components had sustained some damage due to lack of lubrication, overall they were in very good condition. The testing provided evidence that AgustaWestland’s design approach and the proprietary way in which residual oil is distributed make it possible to extend the run dry period from the basic 30 minutes requirement to more than 60 minutes.
Current civil airworthiness authorities’ rules state that during any failure resulting in total loss of lubricant the aircraft must be capable of safe operation for at least 30 minutes after the crew is alerted to the problem. AgustaWestland with these results is setting new standards of safety in the industry and anticipating future airworthiness rules.
This latest achievement was made possible by AgustaWestland’s long established leadership and expertise in transmission system and gearbox design, the quality of the AW139 MGB basic design as well as leveraging on the new generation AW189 main gearbox technology. The AW189’s unique 50 minutes run dry capability were certified by EASA in early 2014 and benefit from the Family concept approach. Some of the AW189 MGB characteristics were transferred into the AW139 MGB to further enhance its run dry capabilities, to ensure even greater levels of reliability and safety in the event of loss of oil.
This new enhancement is also beneficial to the AW139M, increasing its survivability in demanding battlefield scenarios. This new configuration will soon be available (and can be retro-fitted to existing AW139 MGB) as an option for customers wanting increased safety and extended performance after loss of oil, something of particular interest for offshore operations.
The AW139 is a new generation intermediate twin-turbine helicopter setting new standards in its class and continues to be unmatched in category with a 56% market share. To date, orders for almost 900 AW139 helicopters have been placed by over 220 customers from almost 70 countries to carry out a wide range of missions including offshore transport, law enforcement and homeland security duties, EMS/SAR, utility, firefighting, executive/private transport and other government roles.
AgustaWestland’s approach to reducing the risk of loss of oil from transmission systems differs from and is unrivalled even by the latest competitor’s designs. First of all in the area of design, obsessive care is taken to the detail. The design of most main gearboxes includes a heat exchanger, to cool the oil, and a fan to draw in the air – typically these are located away from the main gearbox itself and connected to the main casing via pipes, hoses and fittings. Avoiding these external components is one way to mitigate the risk of catastrophic loss of lubrication.
Since the early 1980s AgustaWestland has developed the heat exchanger installation integrally fitted to the main gearbox casing and has replaced external pipes with integrated cored oil passages.
AgustaWestland designs also include redundancy of the lubrication system with dual pumps working in parallel to ensure sufficient oil flow should one pump fail and the low pressure warning be activated. Other measures include fail-safe capability on pressurised fittings, independent lubrication (sealed grease or oil) to mechanically-driven rotating components and multiple ‘green run’ testing and systems checks during assembly.
Finally, the ability to reduce heat generation within the main gearbox during a loss of oil event is an important factor because this means less demand is placed on the residual reserves of oil. AgustaWestland has introduced measures to minimise friction through super finishing of gears and the introduction of special treatments and coatings as well as the use of heat-tolerant materials and careful design choices.