Extract from Boeing MOM issued Thursday 26th Feb:
Rolls-Royce has developed a modification to the FOHE to mitigate the potential for a future fuel system ice accumulation and release event resulting in a restriction at the inlet to the FOHE. Information on the proposed modification is provided via the ref /E/ Rolls-Royce Worldwide Communication (WWC). As noted in ref /E/, the modified FOHE is similar to the existing unit except that the fuel tube inlets are flush mounted to the inlet face plate instead of being proud of the inlet face plate. Testing has demonstrated a significant improvement in the tolerance to the arrival of ice at the inlet face plate in respect of ice quantity and fuel temperature.
Boeing and Rolls-Royce are working with the FAA and EASA to determine the most expedient path to certify the proposed FOHE redesign. Pending certification of the redesigned FOHE, Rolls-Royce is targeting service bulletin release in the third quarter of 2009. Per the ref /E/ WWC, the plan for allocating modified FOHEs is currently being developed and will be communicated with each operator individually once available.