FAA officials have issued a final airworthiness directive (AD) calling on operators of hundreds of Embraer ERJ-135 and ERJ-145 jets to replace the spinners on their Rolls-Royce turbofan engines during the next engine maintenance visit or within 4,000 cycles.

Issued after a spinner from an AE3007A engine became detached in flight from a Trans States Airlines Embraer ERJ-145LR (N814HK) climbing through 31,000ft on 19 May 2005, the AD will impact 1,600 engines on regional aircraft and business jets, costing about $13,000 per engine in parts. The aircraft returned to the St Louis International airport, its departure point, after the incident. There were no injuries to the 54 on board.

The National Transportation Safety Board (NTSB) determined in 2007 that the probable cause for the uncontained left engine failure on American Connection flight 5699 was "fatigue failure" of the fan spinner and retaining ring due to an "interference between the mating parts resulting from the inadequate design by the manufacturer".

After the incident, Rolls-Royce had initiated a one-time on-wing eddy current inspection of the spinners while the company initiated a re-design of the part, according to the NTSB.

The FAA estimates it will take one hour of labour to replace each spinner, bringing the total cost of the fleet-wide change out to $20.8 million.

Source: Air Transport Intelligence news