It looks like there will be a vast range of modification states in service across the fleet for several years to come.
The Phase III housing due from this summer on still has the same 1400 hour life limit as the Phase II (i.e. just 8 or 9 months for a high usage S-92). Its installation needs a far bit of specialist work on fuselage frames at STA 328 and 361 as it is dependent on removing current bushes, drilling the frames and then installing larger press-fit bushes.
Next, in Q4 2011, come 'stronger' gears with a higher spec finish to reduce spalling damage. These will only be installed at overhaul.
Their benefit will be traded for an increase in aircraft gross weight. Time will tell what the affect of a weight increase on durability. Does any one know what Phase Housing will be a pre-requiste for the 27,700 lb gross weight?
After that is the Phase IV, or 'Improved Durability' housing (the IDMGB mentioned above). That will come in 2013, over 10 years after the original certification. Only one feature currently claimed for that unit is clearly a direct durability improvement as the others deal with known failure modes or detection problems:
- Adding another means to scavange oil from the input modules to stop the build-up oil oil that caused problems in Brunei in 2008
- Repostioned chip detectors
- An 'integrated bypass valve' - which is seemingly different to the new bypass automation.
- Stronger free wheel bearings - the one clear durability improvement
There is no talk yet of anything that would address the TSB recommendations after the Cougar accident.
At Heli-Expo there was also talk of a new filter insert this year to tackle the problem the current filter has coping with normal spec oil.
Has anyone got the automatic oil cooler bypass installed yet?