The US's National Transportation Safety Board is probing an "uncommanded rollback" on a Rolls-Royce Trent 895 engine which affected a Delta Air Lines Boeing 777-200ER on 26 November, Flight International reports.

NTSB explains that Delta Flight 18, from Shanghai to Atlanta, experienced loss of thrust on the right-hand engine at 39,000ft. Its initial report elaborates: "Initial data indicates that following the rollback, the crew descended to FL310 (approximately 31,000ft) and executed applicable flight manual procedures. The engine recovered and responded normally thereafter. The flight continued to Atlanta where it landed without further incident."

Senior investigator Bill English - due to meet Boeing regarding the incident - is apparently "looking into" the possibility there might be similarities to the Heathrow 777 incident which saw BA038 (G-YMMM) suffer reduced thrust in both Rolls-Royce RB211 Trent 895-17 engines while coming into land and fall short of the runway.

An Air Accidents Investigation Branch (AAIB) report into BA038 concluded "that the fuel flow to both engines was restricted; most probably due to ice within the fuel feed system". It added: "The ice is likely to have formed from water that occurred naturally in the fuel whilst the aircraft operated for a long period, with low fuel flows, in an unusually cold environment."

Flight International notes that in light of the AAIB findings, the Federal Aviation Administration back in September "issued an airworthiness directive calling on operators of 777-200 and -300 aircraft equipped with Trent engines to revise flight manuals to include in-flight procedures for pilots to follow during certain cold-weather conditions and for operations on the ground".

English and fellow investigators are now examining the Delta aircraft's flight data recorder "and other applicable data and components". ®