Boeing Bulletins

GEN-5 : EICAS Indication Of Impending Engine Fuel Filter Bypass

25 June 1996

Effectivity

Please refer to source document.

Reason

This bulletin informs flight crews of the requirement to check EICAS status messages for indication of impending engine fuel filter bypass.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM), the AFM shall supersede. The Boeing Company regards the information or procedures described herein as having a direct or indirect bearing on the safe operation of this model airplane.

Background Information

Fuel contamination can lead to fuel starvation and engine power loss. Each engine fuel system is equipped with a filter to remove contaminants, and a pressure relief valve to allow bypass of an obstructed filter element. A pressure differential switch provides EICAS indication of filter element obstruction prior to pressure relief valve actuation and filter bypass.

Impending fuel filter bypass is indicated only by the EICAS status message L/R ENG FUEL FILT. A recent finding by the US Federal Aviation Administration (FAA) determined a status level message does not provide appropriate indication of this condition. As a result, a L/R ENG FUEL FILT advisory message will be incorporated into the EICAS computer at a future date. Until the updated EICAS computers are installed, FAA Airworthiness Directive AD 96-07-09 requires flight crews to check EICAS for the status message L/R ENG FUEL FILT. If other status level messages are observed as a consequence of complying with this Airworthiness Directive, the flight crew may deal with them in accordance with the appropriate operator policy.

This bulletin contains instructions for checking status messages and a new Engine Fuel Filter non-normal procedure.

Operating Instructions

If the EICAS status cue is displayed anytime after engine start, check the status display for the status message L/R ENG FUEL FILT. If a L/R ENG FUEL FILT status message is displayed, refer to the Engine Fuel Filter non-normal procedure in the QRH. Specific crew action in response to single or multiple L/R ENG FUEL FILT messages is not established by Boeing or the FAA. Any crew action is left up to the individual operator policy.

This requirement will remain in effect until updated EICAS computers are installed.

Boeing policy on flight crew use of status messages has not changed. After engine start, any condition having adverse effect on safe continuation of the flight, requiring crew attention, will appear as an EICAS alert message (warning, caution or advisory). Operators are encouraged to upgrade the EICAS computers in existing fleet airplanes as soon as the upgrade is available.

Administrative Information (Extract)

This anomaly is corrected by Boeing Service Bulletin 757-31-0059.