Potential issue for operators of CF6-50 powered freighters

We included this in last night’s issue of Cargo Facts Update (and yes, if you don’t already subscribe, you should) but I think it deserves wider notice, and I’d like to hear your comments on it, so I’ll put it up here.

In a move that has potential to impact the worldwide freighter fleet, the US National Transportation Safety Board (NTSB) issued an urgent safety recommendation to the FAA, asking the FAA to implement severe restrictions on the operation of aircraft powered by CF6-50 and CF6-45 engines. This includes A300B4s, DC-10-30s, and 747-100s/-200s/-300s – aircraft that are now primarily operated in freighter configuration.

The background to the recommendation is that in the last two years there have been four uncontained
CF6-50 engine failures (caused by failure of the low pressure turbine stage 3 disk), and although there have no injuries or crashes, the NTSB has determined that current regulations are not sufficient to prevent further failures. It has therefore recommended that, among other things, the FAA do the following:

• Immediately require operators of CF6-45/-50-powered airplanes to perform high pressure turbine rotor blade borescope inspections every 15 flight cycles.
• Immediately require General Electric Company to redesign the CF6-45/-50 low pressure turbine stage 3 diskso that it will not fail when exposed to high pressure rotor unbalance forces.
• Require all operators of CF6-45/-50-powered airplanes to install the newly designed LPT S3 at the next maintenance opportunity once it is available from GE.

The FAA is not required to act on these recommendations, but uncontained engine failures are not something easily ignored. If the FAA does implement the NTSB recommendations in the form of an Airworthiness Directive,
the impact on operators of CF6-50-powered freighters would be immediate and financially onerous.

The current active fleet of affected aircraft is roughly as follows:

A300B4Fs 45 (some of which may be Pratt-powered, and therefore not affected)
DC/MD-10-30Fs 35 (17 of which are operated by FedEx)
747-100/-200/-300Fs 75 (not all of which are CF6-powered)

Full text of the NTSB recommendation can be found at www.ntsb.gov/Recs/letters/2010/A-10-098-101.pdf