What is actually envolved in a CBR??
Imagine a cross section of the Hornet's centre fuselage (not counting the upper fuselage spine area) taken just behind the intakes and going back about 3 metres, that's the 'centre barrel'. It comprises three major pieces each about a metre long and through which the air intakes run, and a few smaller pieces which form attachment points. The aircraft's forward fuselage, engine mounts, wings and mounts, fuselage fuel tanks, and undercarriage are all attached to it, so it's obviously THE key structural part of the aircraft. Barra might be able to elaborate...
All Hornet centre barrels are built by Northrop Grumman at El Segundo in LA. (I've been there a couple of times and thought about backing El Segundo in the Cox Plate last weekend...wish I had now!)
The 'classic' Hornet was originally cleared to a fatigue life of about 6500 hours, however US Navy Hornets started experiencing some severe cracking at 4300 hours, hence the CBR program being initiated. Canada and then Australia also started seeing some fatigue cracking, although it was far less severe and in different areas to those of the US Navy jets. US jets are primarily employed on air-to-ground duties and have to land on and be thrown off carriers, whereas Canadian and Aussie jets have a higher emphasis on air-to-air and therefore use their fatigue up in different areas.
Canada originally had 130-odd CF-18s and opted to do CBRs on 80 jets, but after doing 13 CBRs they then suspended their program and re-certified their jets for 9000 hours. This will be managed by performing reactive and proactive maintenence on cracks, in much the same way as the RAAF did Phase 3.1 of the HUG program. The US Navy are only doing a few CBRs a year and then only on F/A-18C/D aircraft with the later avionics fit, but are seemingly leaning towards ordering more Supers instead.
If it is indeed not viable the what would the service life be for most of the bugs we have ATM?? would 2018 be viable at all without the programme?
Without some intense fatigue management, the older RAAF jets will start falling over around 2012, with the bulk of the fleet becoming unviable from late 2015 onwards. However, if we took the brave (but unlikely) step and re-certified ours for say, 7500 hours and did additional HUG 3.1 stuff, we might get 40 or so jets through to 2017 or later.
Cheers